Bump version and update feature list

- Rename openStreamFor* methods to more accurate openChannelFor*
 - Fix ArrayByteChannel having an incorrect .position() implementation

Cherry-picked from the PR against dan200/ComputerCraft

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,16 @@
+---
+name: Bug report
+about: Report some misbehaviour in the mod
+
+---
+
+<!--
+## Before reporting
+ - Search for the bug both here and [on the ComputerCraft issues page](https://github.com/dan200/ComputerCraft/issues?utf8=%E2%9C%93&q=is%3Aissue+)
+ - If possible, try to reproduce on vanilla ComputerCraft. If it still occurs, [report on the ComputerCraft repo](https://github.com/dan200/ComputerCraft/issues/new) instead.
+-->
+
+## Useful information to include:
+ - Minecraft version
+ - CC: Tweaked version
+ - Detailed reproduction steps!** Sometimes I can spot a bug pretty easily, but often it's much more obscure. Anything you can give which will help reproduce it means it'll get fixed quicker.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,15 @@
+---
+name: Feature request
+about: Suggest an idea or improvement
+
+---
+
+<!--
+## Before reporting
+ - Search for the suggestion both here and [on the ComputerCraft issues page](https://github.com/dan200/ComputerCraft/issues?utf8=%E2%9C%93&q=is%3Aissue+). It's possible someone's suggested it before!
+ - Unless something is specific to CC:Tweaked, try to [suggest them on the ComputerCraft repo](https://github.com/dan200/ComputerCraft/issues/new). There's a lot more people watching it, so it allows the wider community to contribute.
+-->
+
+## Useful information to include:
+ - Explanation of how the feature/change chould work.
+ - Some rationale/use case for a feature. I'd like to keep CC:T as minimal

.github/pull_request_template.md

@@ -0,0 +1,9 @@
+<!--
+Unless this feature is specific to CC:Tweaked, try to [target the original ComputerCraft repo](https://github.com/dan200/ComputerCraft/) instead. There's a lot more people watching it, so it allows the wider community to contribute.
+-->
+
+## Useful information to include:
+ - Brief explanation of the changes you've made.
+ - Rationale of why this change has been made/reasoning behind it.
+
+The more information you can provide, the easier it is to review something now _and_ to see why a change was made, when the code needs updating in the future.

README.md

@@ -6,26 +6,44 @@ features of the mod. For a more stable experience, I recommend checking out the
 [original mod](https://github.com/dan200/ComputerCraft).
 
 ## What?
-CC: Tweaked does not aim to create a competing fork of ComputerCraft, nor am I planning to take it in in a vastly
-different direction to the original mod. In fact, CC: Tweaked aims to be a nurturing ground for various features, with
-a pull request against the original mod being the end goal.
+CC: Tweaked (or CC:T for short) does not aim to create a competing fork of ComputerCraft, nor am I planning to take it
+in in a vastly different direction to the original mod. In fact, CC:T aims to be a nurturing ground for various
+features, with a pull request against the original mod being the end goal.
 
-CC: Tweaked also includes many pull requests from the community which have not yet been merged, offering a large number
+CC:T also includes many pull requests from the community which have not yet been merged, offering a large number
 of additional bug fixes and features over the original mod.
 
+## Features
+CC: Tweaked contains the all features of the latest alpha, as well as numerous fixes, performance improvements and
+several additional features. I'd recommend checking out [the releases page](https://github.com/SquidDev-CC/CC-Tweaked/releases)
+to see the full changes, but here's a couple of the more interesting changes:
+
+ - Replace LuaJ with Cobalt.
+ - Allow running multiple computers at the same time.
+ - Websocket support in the HTTP library.
+ - Wired modems and cables act more like multiparts.
+ - Add map-like rendering for pocket computers and printed pages/books.
+ - Adds the `/computercraft` command, offering various diagnostic tools for server owners. This allows operators to
+   track which computers are hogging resources, turn on and shutdown multiple computers at once and interact with
+   computers remotely.
+ - Add full-block wired modems, allowing one to wrap non-solid peripherals (such as turtles, or chests if Plethora is
+   installed).
+ - Extended binary file handles. They support file seeking, and reading new lines, allowing full (and accurate)
+   emulation of the standard Lua `io` library.
+
 ## Relation to CCTweaks?
-This mod has nothing to do with CCTweaks, though there is no denying the name is a throwback to it. However, I do plan
-to migrate some features of CCTweaks into CC: Tweaked.
+This mod has nothing to do with CCTweaks, though there is no denying the name is a throwback to it. That being said,
+several features have been included, such as full block modems, the Cobalt runtime and map-like rendering for pocket
+computers.
 
 ## Contributing
 Any contribution is welcome, be that using the mod, reporting bugs or contributing code. If you do wish to contribute
-code, do consider submitting it to the ComputerCraft repository instead.
+code, do consider submitting it to the ComputerCraft repository first.
 
-That being said, in order to start helping develop CC: Tweaked, you'll need to follow these steps:
+That being said, in order to start helping develop CC:T, you'll need to follow these steps:
 
  - **Clone the repository:** `git clone https://github.com/SquidDev-CC/CC-Tweaked.git && cd CC-Tweaked`
  - **Setup Forge:** `./gradlew setupDecompWorkspace`
  - **Test your changes:** `./gradlew runClient` (or run the `GradleStart` class from your IDE).
- 
-If you want to run CC: Tweaked in a normal Minecraft instance, run `./gradlew build` and copy the `.jar` from 
-`build/libs`.
+
+If you want to run CC:T in a normal Minecraft instance, run `./gradlew build` and copy the `.jar` from `build/libs`.

build.gradle

@@ -13,22 +13,22 @@ buildscript {
         classpath 'org.ajoberstar:gradle-git:1.6.0'
     }
 }
+
+plugins {
+    id 'com.matthewprenger.cursegradle' version '1.0.10'
+}
+
 apply plugin: 'net.minecraftforge.gradle.forge'
 apply plugin: 'org.ajoberstar.grgit'
+apply plugin: 'maven-publish'
+apply plugin: 'maven'
 
-/*
-// for people who want stable - not yet functional for MC 1.8.8 - we require the forgegradle 2.1 snapshot
-plugins {
-    id "net.minecraftforge.gradle.forge" version "2.0.2"
-}
-*/
-
-version = "1.80pr1.1"
+version = "1.80pr1.9"
 group = "org.squiddev"
 archivesBaseName = "cc-tweaked"
 
 minecraft {
-    version = "1.12-14.21.1.2387"
+    version = "1.12.2-14.23.4.2749"
     runDir = "run"
     replace '${version}', project.version
 
@@ -37,7 +37,7 @@ minecraft {
     // stable_#            stables are built at the discretion of the MCP team.
     // Use non-default mappings at your own risk. they may not allways work.
     // simply re-run your setup task after changing the mappings to update your workspace.
-    mappings = "snapshot_20170629"
+    mappings = "snapshot_20180724"
     // makeObfSourceJar = false // an Srg named sources jar is made by default. uncomment this to disable.
 }
 
@@ -50,17 +50,27 @@ repositories {
         name = "squiddev"
         url = "https://dl.bintray.com/squiddev/maven"
     }
+
+    ivy { artifactPattern "https://asie.pl/files/mods/Charset/LibOnly/[module]-[revision](-[classifier]).[ext]" }
 }
 
 configurations {
     shade
     compile.extendsFrom shade
+    deployerJars
 }
 
 dependencies {
-    deobfProvided "mezz.jei:jei_1.12:4.7.5.86:api"
-    runtime "mezz.jei:jei_1.12:4.7.5.86"
-    shade 'org.squiddev:Cobalt:0.3.0'
+    deobfProvided "mezz.jei:jei_1.12.2:4.8.5.159:api"
+    deobfProvided "pl.asie:Charset-Lib:0.5.4.6"
+
+    runtime "mezz.jei:jei_1.12.2:4.8.5.159"
+
+    shade 'org.squiddev:Cobalt:0.3.2'
+
+    testCompile 'junit:junit:4.11'
+
+    deployerJars "org.apache.maven.wagon:wagon-ssh:3.0.0"
 }
 
 javadoc {
@@ -115,6 +125,69 @@ processResources {
     }
 }
 
+
+curseforge {
+    apiKey = project.hasProperty('curseForgeApiKey') ? project.curseForgeApiKey : ''
+    project {
+        id = '282001'
+        releaseType = 'beta'
+        changelog = "Release notes can be found on the GitHub repository (https://github.com/SquidDev-CC/CC-Tweaked/releases/tag/v${project.version})."
+    }
+}
+
+publishing {
+    publications {
+        mavenJava(MavenPublication) {
+            from components.java
+            artifact sourceJar
+        }
+    }
+}
+
+uploadArchives {
+    repositories {
+        if(project.hasProperty('mavenUploadUrl')) {
+            mavenDeployer {
+                configuration = configurations.deployerJars
+
+                repository(url: project.property('mavenUploadUrl')) {
+                    authentication(
+                        userName: project.property('mavenUploadUser'),
+                        privateKey: project.property('mavenUploadKey'))
+                }
+
+                pom.project {
+                    name 'CC: Tweaked'
+                    packaging 'jar'
+                    description 'A fork of ComputerCraft which aims to provide earlier access to the more experimental and in-development features of the mod.'
+                    url 'https://github.com/SquidDev-CC/CC-Tweaked'
+
+                    scm {
+                        url 'https://github.com/dan200/ComputerCraft.git'
+                    }
+
+                    issueManagement {
+                        system 'github'
+                        url 'https://github.com/dan200/ComputerCraft/issues'
+                    }
+
+                    licenses {
+                        license {
+                            name 'ComputerCraft Public License, Version 1.0'
+                            url 'https://github.com/dan200/ComputerCraft/blob/master/LICENSE'
+                            distribution 'repo'
+                        }
+                    }
+                }
+
+                pom.whenConfigured { pom ->
+                    pom.dependencies.clear()
+                }
+            }
+        }
+    }
+}
+
 gradle.projectsEvaluated {
     tasks.withType(JavaCompile) {
         options.compilerArgs << "-Xlint"

settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'cc-tweaked'

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -7,28 +7,37 @@
 package dan200.computercraft;
 
 import com.google.common.base.CaseFormat;
+import com.google.common.base.Converter;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
 import dan200.computercraft.api.lua.ILuaAPIFactory;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.media.IMediaProvider;
 import dan200.computercraft.api.network.IPacketNetwork;
+import dan200.computercraft.api.network.wired.IWiredElement;
+import dan200.computercraft.api.network.wired.IWiredNode;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheralProvider;
 import dan200.computercraft.api.permissions.ITurtlePermissionProvider;
 import dan200.computercraft.api.pocket.IPocketUpgrade;
 import dan200.computercraft.api.redstone.IBundledRedstoneProvider;
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import dan200.computercraft.api.turtle.event.TurtleAction;
 import dan200.computercraft.core.apis.AddressPredicate;
 import dan200.computercraft.core.filesystem.ComboMount;
 import dan200.computercraft.core.filesystem.FileMount;
-import dan200.computercraft.core.filesystem.JarMount;
+import dan200.computercraft.core.filesystem.FileSystemMount;
+import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.core.tracking.Tracking;
 import dan200.computercraft.shared.command.CommandComputer;
+import dan200.computercraft.shared.command.CommandComputerCraft;
 import dan200.computercraft.shared.common.DefaultBundledRedstoneProvider;
 import dan200.computercraft.shared.computer.blocks.BlockCommandComputer;
 import dan200.computercraft.shared.computer.blocks.BlockComputer;
 import dan200.computercraft.shared.computer.blocks.TileComputer;
 import dan200.computercraft.shared.computer.core.ClientComputerRegistry;
+import dan200.computercraft.shared.computer.core.ComputerFamily;
+import dan200.computercraft.shared.computer.core.ServerComputer;
 import dan200.computercraft.shared.computer.core.ServerComputerRegistry;
 import dan200.computercraft.shared.media.items.ItemDiskExpanded;
 import dan200.computercraft.shared.media.items.ItemDiskLegacy;
@@ -38,6 +47,7 @@ import dan200.computercraft.shared.network.ComputerCraftPacket;
 import dan200.computercraft.shared.network.PacketHandler;
 import dan200.computercraft.shared.peripheral.common.BlockCable;
 import dan200.computercraft.shared.peripheral.common.BlockPeripheral;
+import dan200.computercraft.shared.peripheral.common.BlockWiredModemFull;
 import dan200.computercraft.shared.peripheral.diskdrive.TileDiskDrive;
 import dan200.computercraft.shared.peripheral.modem.BlockAdvancedModem;
 import dan200.computercraft.shared.peripheral.modem.WirelessNetwork;
@@ -51,6 +61,8 @@ import dan200.computercraft.shared.turtle.blocks.BlockTurtle;
 import dan200.computercraft.shared.turtle.blocks.TileTurtle;
 import dan200.computercraft.shared.turtle.upgrades.*;
 import dan200.computercraft.shared.util.*;
+import dan200.computercraft.shared.wired.CapabilityWiredElement;
+import dan200.computercraft.shared.wired.WiredNode;
 import io.netty.buffer.Unpooled;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.player.EntityPlayer;
@@ -58,11 +70,13 @@ import net.minecraft.entity.player.EntityPlayerMP;
 import net.minecraft.item.ItemStack;
 import net.minecraft.network.PacketBuffer;
 import net.minecraft.server.MinecraftServer;
+import net.minecraft.tileentity.TileEntity;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.EnumHand;
 import net.minecraft.util.NonNullList;
 import net.minecraft.util.SoundEvent;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.IBlockAccess;
 import net.minecraft.world.World;
 import net.minecraftforge.common.config.ConfigCategory;
 import net.minecraftforge.common.config.Configuration;
@@ -83,7 +97,11 @@ import java.io.*;
 import java.net.MalformedURLException;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.ProviderNotFoundException;
 import java.util.*;
+import java.util.function.Function;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 
@@ -108,6 +126,7 @@ public class ComputerCraft
     // ComputerCraftEdu uses ID 104
     public static final int printoutGUIID = 105;
     public static final int pocketComputerGUIID = 106;
+    public static final int viewComputerGUIID = 110;
 
     // Configuration options
     private static final String[] DEFAULT_HTTP_WHITELIST = new String[] { "*" };
@@ -135,6 +154,7 @@ public class ComputerCraft
     public static int advancedTurtleFuelLimit = 100000;
     public static boolean turtlesObeyBlockProtection = true;
     public static boolean turtlesCanPush = true;
+    public static EnumSet<TurtleAction> turtleDisabledActions = EnumSet.noneOf( TurtleAction.class );
 
     public static final int terminalWidth_computer = 51;
     public static final int terminalHeight_computer = 19;
@@ -167,6 +187,7 @@ public class ComputerCraft
         public static BlockTurtle turtleAdvanced;
         public static BlockCommandComputer commandComputer;
         public static BlockAdvancedModem advancedModem;
+        public static BlockWiredModemFull wiredModemFull;
     }
 
     public static class Items
@@ -217,6 +238,7 @@ public class ComputerCraft
         public static Property advancedTurtleFuelLimit;
         public static Property turtlesObeyBlockProtection;
         public static Property turtlesCanPush;
+        public static Property turtleDisabledActions;
 
         public static Property modem_range;
         public static Property modem_highAltitudeRange;
@@ -272,6 +294,18 @@ public class ComputerCraft
 
         // Load config
         Config.config = new Configuration( event.getSuggestedConfigurationFile() );
+        loadConfig();
+
+        // Setup network
+        networkEventChannel = NetworkRegistry.INSTANCE.newEventDrivenChannel( "CC" );
+        networkEventChannel.register( new PacketHandler() );
+
+        proxy.preInit();
+        turtleProxy.preInit();
+    }
+
+    public static void loadConfig()
+    {
         Config.config.load();
 
         Config.http_enable = Config.config.get( Configuration.CATEGORY_GENERAL, "http_enable", http_enable );
@@ -360,6 +394,9 @@ public class ComputerCraft
         Config.turtlesCanPush = Config.config.get( Configuration.CATEGORY_GENERAL, "turtlesCanPush", turtlesCanPush );
         Config.turtlesCanPush.setComment( "If set to true, Turtles will push entities out of the way instead of stopping if there is space to do so" );
 
+        Config.turtleDisabledActions = Config.config.get( Configuration.CATEGORY_GENERAL, "turtle_disabled_actions", new String[ 0 ] );
+        Config.turtleDisabledActions.setComment( "A list of turtle actions which are disabled." );
+
         Config.maxNotesPerTick = Config.config.get( Configuration.CATEGORY_GENERAL, "maxNotesPerTick", maxNotesPerTick );
         Config.maxNotesPerTick.setComment( "Maximum amount of notes a speaker can play at once" );
 
@@ -369,13 +406,6 @@ public class ComputerCraft
         }
 
         syncConfig();
-
-        // Setup network
-        networkEventChannel = NetworkRegistry.INSTANCE.newEventDrivenChannel( "CC" );
-        networkEventChannel.register( new PacketHandler() );
-
-        proxy.preInit();
-        turtleProxy.preInit();
     }
 
     public static void syncConfig() {
@@ -407,6 +437,20 @@ public class ComputerCraft
         turtlesObeyBlockProtection = Config.turtlesObeyBlockProtection.getBoolean();
         turtlesCanPush = Config.turtlesCanPush.getBoolean();
 
+        turtleDisabledActions.clear();
+        Converter<String, String> converter = CaseFormat.LOWER_CAMEL.converterTo( CaseFormat.UPPER_UNDERSCORE );
+        for( String value : Config.turtleDisabledActions.getStringList() )
+        {
+            try
+            {
+                turtleDisabledActions.add( TurtleAction.valueOf( converter.convert( value ) ) );
+            }
+            catch( IllegalArgumentException e )
+            {
+                ComputerCraft.log.error( "Unknown turtle action " + value );
+            }
+        }
+
         maxNotesPerTick = Math.max(1, Config.maxNotesPerTick.getInt());
 
         Config.config.save();
@@ -422,7 +466,7 @@ public class ComputerCraft
     @Mod.EventHandler
     public void onServerStarting( FMLServerStartingEvent event )
     {
-        event.registerServerCommand( new CommandComputer() );
+        proxy.initServer( event.getServer() );
     }
 
     @Mod.EventHandler
@@ -432,6 +476,7 @@ public class ComputerCraft
         {
             ComputerCraft.serverComputerRegistry.reset();
             WirelessNetwork.resetNetworks();
+            Tracking.reset();
         }
     }
 
@@ -442,6 +487,7 @@ public class ComputerCraft
         {
             ComputerCraft.serverComputerRegistry.reset();
             WirelessNetwork.resetNetworks();
+            Tracking.reset();
         }
     }
 
@@ -465,11 +511,6 @@ public class ComputerCraft
         return proxy.getRenderFrame();
     }
 
-    public static void deleteDisplayLists( int list, int range )
-    {
-        proxy.deleteDisplayLists( list, range );
-    }
-
     public static Object getFixedWidthFontRenderer()
     {
         return proxy.getFixedWidthFontRenderer();
@@ -519,6 +560,24 @@ public class ComputerCraft
         player.openGui( ComputerCraft.instance, ComputerCraft.pocketComputerGUIID, player.getEntityWorld(), hand.ordinal(), 0, 0 );
     }
 
+    public static void openComputerGUI( EntityPlayer player, ServerComputer computer )
+    {
+        ComputerFamily family = computer.getFamily();
+        int width = 0, height = 0;
+        Terminal terminal = computer.getTerminal();
+        if( terminal != null )
+        {
+            width = terminal.getWidth();
+            height = terminal.getHeight();
+        }
+        
+        // Pack useful terminal information into the various coordinate bits.
+        // These are extracted in ComputerCraftProxyCommon.getClientGuiElement
+        player.openGui( ComputerCraft.instance, ComputerCraft.viewComputerGUIID, player.getEntityWorld(),
+            computer.getInstanceID(), family.ordinal(), (width & 0xFFFF) << 16 | (height & 0xFFFF)
+        );
+    }
+
     public static File getBaseDir()
     {
         return FMLCommonHandler.instance().getMinecraftServerInstance().getFile(".");
@@ -680,6 +739,11 @@ public class ComputerCraft
         }
     }
 
+    public static IWiredNode createWiredNodeForElement( IWiredElement element )
+    {
+        return new WiredNode( element );
+    }
+
     public static IPeripheral getPeripheralAt( World world, BlockPos pos, EnumFacing side )
     {
         // Try the handlers in order:
@@ -701,6 +765,14 @@ public class ComputerCraft
         return null;
     }
 
+    public static IWiredElement getWiredElementAt( IBlockAccess world, BlockPos pos, EnumFacing side )
+    {
+        TileEntity tile = world.getTileEntity( pos );
+        return tile != null && tile.hasCapability( CapabilityWiredElement.CAPABILITY, side )
+            ? tile.getCapability( CapabilityWiredElement.CAPABILITY, side )
+            : null;
+    }
+
     public static int getDefaultBundledRedstoneOutput( World world, BlockPos pos, EnumFacing side )
     {
         if( WorldUtil.isBlockInWorld( world, pos ) )
@@ -802,7 +874,7 @@ public class ComputerCraft
         return upgrades;
     }
 
-    public IPacketNetwork getWirelessNetwork()
+    public static IPacketNetwork getWirelessNetwork()
     {
         return WirelessNetwork.getUniversal();
     }
@@ -853,11 +925,12 @@ public class ComputerCraft
         {
             try
             {
-                IMount jarMount = new JarMount( modJar, subPath );
-                mounts.add( jarMount );
+                FileSystem fs = FileSystems.newFileSystem( modJar.toPath(), ComputerCraft.class.getClassLoader() );
+                mounts.add( new FileSystemMount( fs, subPath ) );
             }
-            catch( IOException e )
+            catch( IOException | ProviderNotFoundException | ServiceConfigurationError e )
             {
+                ComputerCraft.log.error( "Could not load mount from mod jar", e );
                 // Ignore
             }
         }
@@ -875,7 +948,7 @@ public class ComputerCraft
                     if( !resourcePack.isDirectory() )
                     {
                         // Mount a resource pack from a jar
-                        IMount resourcePackMount = new JarMount( resourcePack, subPath );
+                        IMount resourcePackMount = new FileSystemMount( FileSystems.getFileSystem( resourcePack.toURI() ), subPath );
                         mounts.add( resourcePackMount );
                     }
                     else
@@ -891,7 +964,7 @@ public class ComputerCraft
                 }
                 catch( IOException e )
                 {
-                    // Ignore
+                    ComputerCraft.log.error( "Could not load resource pack '" + resourcePack1 + "'", e );
                 }
             }
         }
@@ -1040,7 +1113,7 @@ public class ComputerCraft
     {
         return turtleProxy.getTurtleUpgrade( id );
     }
-
+    
     public static ITurtleUpgrade getTurtleUpgrade( int legacyID )
     {
         return turtleProxy.getTurtleUpgrade( legacyID );
@@ -1056,13 +1129,18 @@ public class ComputerCraft
         turtleProxy.addAllUpgradedTurtles( list );
     }
 
-    public static void setEntityDropConsumer( Entity entity, IEntityDropConsumer consumer )
+    public static void setDropConsumer( Entity entity, Function<ItemStack, ItemStack> consumer )
     {
-        turtleProxy.setEntityDropConsumer( entity, consumer );
+        turtleProxy.setDropConsumer( entity, consumer );
     }
 
-    public static void clearEntityDropConsumer( Entity entity )
+    public static void setDropConsumer( World world, BlockPos pos, Function<ItemStack, ItemStack> consumer )
     {
-        turtleProxy.clearEntityDropConsumer( entity );
+        turtleProxy.setDropConsumer( world, pos, consumer );
+    }
+
+    public static List<ItemStack> clearDropConsumer( )
+    {
+        return turtleProxy.clearDropConsumer();
     }
 }

src/main/java/dan200/computercraft/api/ComputerCraftAPI.java

@@ -12,6 +12,8 @@ import dan200.computercraft.api.lua.ILuaAPIFactory;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.media.IMediaProvider;
 import dan200.computercraft.api.network.IPacketNetwork;
+import dan200.computercraft.api.network.wired.IWiredElement;
+import dan200.computercraft.api.network.wired.IWiredNode;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheralProvider;
@@ -21,6 +23,7 @@ import dan200.computercraft.api.redstone.IBundledRedstoneProvider;
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.IBlockAccess;
 import net.minecraft.world.World;
 
 import javax.annotation.Nonnull;
@@ -328,6 +331,61 @@ public final class ComputerCraftAPI
         }
     }
 
+    /**
+     * Construct a new wired node for a given wired element
+     *
+     * @param element The element to construct it for
+     * @return The element's node
+     * @see IWiredElement#getNode()
+     */
+    @Nonnull
+    public static IWiredNode createWiredNodeForElement( @Nonnull IWiredElement element )
+    {
+        findCC();
+        if( computerCraft_createWiredNodeForElement != null )
+        {
+            try
+            {
+                return (IWiredNode) computerCraft_createWiredNodeForElement.invoke( null, element );
+            }
+            catch( ReflectiveOperationException e )
+            {
+                throw new IllegalStateException( "Error creating wired node", e );
+            }
+        }
+        else
+        {
+            throw new IllegalStateException( "ComputerCraft cannot be found" );
+        }
+    }
+
+    /**
+     * Get the wired network element for a block in world
+     *
+     * @param world The world the block exists in
+     * @param pos   The position the block exists in
+     * @param side  The side to extract the network element from
+     * @return The element's node
+     * @see IWiredElement#getNode()
+     */
+    @Nullable
+    public static IWiredElement getWiredElementAt( @Nonnull IBlockAccess world, @Nonnull BlockPos pos, @Nonnull EnumFacing side )
+    {
+        findCC();
+        if( computerCraft_getWiredElementAt != null )
+        {
+            try
+            {
+                return (IWiredElement) computerCraft_getWiredElementAt.invoke( null, world, pos, side );
+            }
+            catch( ReflectiveOperationException ignored )
+            {
+            }
+        }
+        
+        return null;
+    }
+
     // The functions below here are private, and are used to interface with the non-API ComputerCraft classes.
     // Reflection is used here so you can develop your mod without decompiling ComputerCraft and including
     // it in your solution, and so your mod won't crash if ComputerCraft is installed.
@@ -374,6 +432,12 @@ public final class ComputerCraftAPI
                 computerCraft_registerAPIFactory = findCCMethod( "registerAPIFactory", new Class<?>[] {
                     ILuaAPIFactory.class
                 } );
+                computerCraft_createWiredNodeForElement = findCCMethod( "createWiredNodeForElement", new Class<?>[] {
+                    IWiredElement.class
+                } );
+                computerCraft_getWiredElementAt = findCCMethod( "getWiredElementAt", new Class<?>[]{
+                    IBlockAccess.class, BlockPos.class, EnumFacing.class
+                } );
             } catch( Exception e ) {
                 System.out.println( "ComputerCraftAPI: ComputerCraft not found." );
             } finally {
@@ -411,4 +475,6 @@ public final class ComputerCraftAPI
     private static Method computerCraft_registerPocketUpgrade = null;
     private static Method computerCraft_getWirelessNetwork = null;
     private static Method computerCraft_registerAPIFactory = null;
+    private static Method computerCraft_createWiredNodeForElement = null;
+    private static Method computerCraft_getWiredElementAt = null;
 }

src/main/java/dan200/computercraft/api/filesystem/IMount.java

@@ -13,6 +13,8 @@ import net.minecraft.world.World;
 import javax.annotation.Nonnull;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.channels.Channels;
+import java.nio.channels.ReadableByteChannel;
 import java.util.List;
 
 /**
@@ -72,7 +74,25 @@ public interface IMount
      * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
      * @return A stream representing the contents of the file.
      * @throws IOException If the file does not exist, or could not be opened.
+     * @deprecated Use {@link #openChannelForRead(String)} instead
      */
     @Nonnull
+    @Deprecated
     InputStream openForRead( @Nonnull String path ) throws IOException;
+
+    /**
+     * Opens a file with a given path, and returns an {@link ReadableByteChannel} representing its contents.
+     *
+     * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
+     * @return A channel representing the contents of the file. If the channel implements
+     * {@link java.nio.channels.SeekableByteChannel}, one will be able to seek to arbitrary positions when using binary
+     * mode.
+     * @throws IOException If the file does not exist, or could not be opened.
+     */
+    @Nonnull
+    @SuppressWarnings("deprecation")
+    default ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
+    {
+        return Channels.newChannel( openForRead( path ) );
+    }
 }

src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java

@@ -13,6 +13,8 @@ import net.minecraft.world.World;
 import javax.annotation.Nonnull;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.channels.Channels;
+import java.nio.channels.WritableByteChannel;
 
 /**
  * Represents a part of a virtual filesystem that can be mounted onto a computer using {@link IComputerAccess#mount(String, IMount)}
@@ -50,20 +52,54 @@ public interface IWritableMount extends IMount
      * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
      * @return A stream for writing to
      * @throws IOException If the file could not be opened for writing.
+     * @deprecated Use {@link #openChannelForWrite(String)} instead.
      */
     @Nonnull
+    @Deprecated
     OutputStream openForWrite( @Nonnull String path ) throws IOException;
 
+    /**
+     * Opens a file with a given path, and returns an {@link OutputStream} for writing to it.
+     *
+     * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
+     * @return A stream for writing to. If the channel implements {@link java.nio.channels.SeekableByteChannel}, one
+     * will be able to seek to arbitrary positions when using binary mode.
+     * @throws IOException If the file could not be opened for writing.
+     */
+    @Nonnull
+    @SuppressWarnings("deprecation")
+    default WritableByteChannel openChannelForWrite( @Nonnull String path ) throws IOException
+    {
+        return Channels.newChannel( openForWrite( path ) );
+    }
+
     /**
      * Opens a file with a given path, and returns an {@link OutputStream} for appending to it.
      *
      * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
      * @return A stream for writing to.
      * @throws IOException If the file could not be opened for writing.
+     * @deprecated Use {@link #openChannelForAppend(String)} instead.
      */
     @Nonnull
+    @Deprecated
     OutputStream openForAppend( @Nonnull String path ) throws IOException;
 
+    /**
+     * Opens a file with a given path, and returns an {@link OutputStream} for appending to it.
+     *
+     * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
+     * @return A stream for writing to. If the channel implements {@link java.nio.channels.SeekableByteChannel}, one
+     * will be able to seek to arbitrary positions when using binary mode.
+     * @throws IOException If the file could not be opened for writing.
+     */
+    @Nonnull
+    @SuppressWarnings("deprecation")
+    default WritableByteChannel openChannelForAppend( @Nonnull String path ) throws IOException
+    {
+        return Channels.newChannel( openForAppend( path ) );
+    }
+
     /**
      * Get the amount of free space on the mount, in bytes. You should decrease this value as the user writes to the
      * mount, and write operations should fail once it reaches zero.

src/main/java/dan200/computercraft/api/network/IPacketNetwork.java

@@ -41,7 +41,8 @@ public interface IPacketNetwork
      * to all receivers within range (or any interdimensional ones).
      *
      * @param packet The packet to send.
-     * @see #transmitInterdimensional(Packet) 
+     * @param range  The maximum distance this packet will be sent.
+     * @see #transmitInterdimensional(Packet)
      * @see IPacketReceiver#receiveSameDimension(Packet, double)
      */
     void transmitSameDimension( @Nonnull Packet packet, double range );
@@ -51,7 +52,7 @@ public interface IPacketNetwork
      * to all receivers across all dimensions.
      *
      * @param packet The packet to send.
-     * @see #transmitSameDimension(Packet, double) 
+     * @see #transmitSameDimension(Packet, double)
      * @see IPacketReceiver#receiveDifferentDimension(Packet)
      */
     void transmitInterdimensional( @Nonnull Packet packet );

src/main/java/dan200/computercraft/api/network/wired/IWiredElement.java

@@ -0,0 +1,29 @@
+package dan200.computercraft.api.network.wired;
+
+import dan200.computercraft.api.ComputerCraftAPI;
+
+import javax.annotation.Nonnull;
+
+/**
+ * An object which may be part of a wired network.
+ *
+ * Elements should construct a node using {@link ComputerCraftAPI#createWiredNodeForElement(IWiredElement)}. This acts
+ * as a proxy for all network objects. Whilst the node may change networks, an element's node should remain constant
+ * for its lifespan.
+ *
+ * Elements are generally tied to a block or tile entity in world. In such as case, one should provide the
+ * {@link IWiredElement} capability for the appropriate sides.
+ */
+public interface IWiredElement extends IWiredSender
+{
+    /**
+     * Called when objects on the network change. This may occur when network nodes are added or removed, or when
+     * peripherals change.
+     *
+     * @param change The change which occurred.
+     * @see IWiredNetworkChange
+     */
+    default void networkChanged( @Nonnull IWiredNetworkChange change )
+    {
+    }
+}

src/main/java/dan200/computercraft/api/network/wired/IWiredNetwork.java

@@ -0,0 +1,80 @@
+package dan200.computercraft.api.network.wired;
+
+import dan200.computercraft.api.peripheral.IPeripheral;
+
+import javax.annotation.Nonnull;
+import java.util.Map;
+
+/**
+ * A wired network is composed of one of more {@link IWiredNode}s, a set of connections between them, and a series
+ * of peripherals.
+ *
+ * Networks from a connected graph. This means there is some path between all nodes on the network. Further more, if
+ * there is some path between two nodes then they must be on the same network. {@link IWiredNetwork} will automatically
+ * handle the merging and splitting of networks (and thus changing of available nodes and peripherals) as connections
+ * change.
+ *
+ * This does mean one can not rely on the network remaining consistent between subsequent operations. Consequently,
+ * it is generally preferred to use the methods provided by {@link IWiredNode}.
+ *
+ * @see IWiredNode#getNetwork()
+ */
+public interface IWiredNetwork
+{
+    /**
+     * Create a connection between two nodes.
+     *
+     * This should only be used on the server thread.
+     *
+     * @param left  The first node to connect
+     * @param right The second node to connect
+     * @return {@code true} if a connection was created or {@code false} if the connection already exists.
+     * @throws IllegalStateException    If neither node is on the network.
+     * @throws IllegalArgumentException If {@code left} and {@code right} are equal.
+     * @see IWiredNode#connectTo(IWiredNode)
+     * @see IWiredNetwork#connect(IWiredNode, IWiredNode)
+     */
+    boolean connect( @Nonnull IWiredNode left, @Nonnull IWiredNode right );
+
+    /**
+     * Destroy a connection between this node and another.
+     *
+     * This should only be used on the server thread.
+     *
+     * @param left  The first node in the connection.
+     * @param right The second node in the connection.
+     * @return {@code true} if a connection was destroyed or {@code false} if no connection exists.
+     * @throws IllegalArgumentException If either node is not on the network.
+     * @throws IllegalArgumentException If {@code left} and {@code right} are equal.
+     * @see IWiredNode#disconnectFrom(IWiredNode)
+     * @see IWiredNetwork#connect(IWiredNode, IWiredNode)
+     */
+    boolean disconnect( @Nonnull IWiredNode left, @Nonnull IWiredNode right );
+
+    /**
+     * Sever all connections this node has, removing it from this network.
+     *
+     * This should only be used on the server thread. You should only call this on nodes
+     * that your network element owns.
+     *
+     * @param node The node to remove
+     * @return Whether this node was removed from the network. One cannot remove a node from a network where it is the
+     * only element.
+     * @throws IllegalArgumentException If the node is not in the network.
+     * @see IWiredNode#remove()
+     */
+    boolean remove( @Nonnull IWiredNode node );
+
+    /**
+     * Update the peripherals a node provides.
+     *
+     * This should only be used on the server thread. You should only call this on nodes
+     * that your network element owns.
+     *
+     * @param node        The node to attach peripherals for.
+     * @param peripherals The new peripherals for this node.
+     * @throws IllegalArgumentException If the node is not in the network.
+     * @see IWiredNode#updatePeripherals(Map)
+     */
+    void updatePeripherals( @Nonnull IWiredNode node, @Nonnull Map<String, IPeripheral> peripherals );
+}

src/main/java/dan200/computercraft/api/network/wired/IWiredNetworkChange.java

@@ -0,0 +1,32 @@
+package dan200.computercraft.api.network.wired;
+
+import dan200.computercraft.api.peripheral.IPeripheral;
+
+import javax.annotation.Nonnull;
+import java.util.Map;
+
+/**
+ * Represents a change to the objects on a wired network.
+ *
+ * @see IWiredElement#networkChanged(IWiredNetworkChange)
+ */
+public interface IWiredNetworkChange
+{
+    /**
+     * A set of peripherals which have been removed. Note that there may be entries with the same name
+     * in the added and removed set, but with a different peripheral.
+     *
+     * @return The set of removed peripherals.
+     */
+    @Nonnull
+    Map<String, IPeripheral> peripheralsRemoved();
+
+    /**
+     * A set of peripherals which have been added. Note that there may be entries with the same name
+     * in the added and removed set, but with a different peripheral.
+     *
+     * @return The set of added peripherals.
+     */
+    @Nonnull
+    Map<String, IPeripheral> peripheralsAdded();
+}

src/main/java/dan200/computercraft/api/network/wired/IWiredNode.java

@@ -0,0 +1,103 @@
+package dan200.computercraft.api.network.wired;
+
+import dan200.computercraft.api.network.IPacketNetwork;
+import dan200.computercraft.api.peripheral.IPeripheral;
+
+import javax.annotation.Nonnull;
+import java.util.Map;
+
+/**
+ * Wired nodes act as a layer between {@link IWiredElement}s and {@link IWiredNetwork}s.
+ *
+ * Firstly, a node acts as a packet network, capable of sending and receiving modem messages to connected nodes. These
+ * methods may be safely used on any thread.
+ *
+ * When sending a packet, the system will attempt to find the shortest path between the two nodes based on their
+ * element's position. Note that packet senders and receivers can have different locations from their associated
+ * element: the distance between the two will be added to the total packet's distance.
+ *
+ * Wired nodes also provide several convenience methods for interacting with a wired network. These should only ever
+ * be used on the main server thread.
+ */
+public interface IWiredNode extends IPacketNetwork
+{
+    /**
+     * The associated element for this network node.
+     *
+     * @return This node's element.
+     */
+    @Nonnull
+    IWiredElement getElement();
+
+    /**
+     * The network this node is currently connected to. Note that this may change
+     * after any network operation, so it should not be cached.
+     *
+     * This should only be used on the server thread.
+     *
+     * @return This node's network.
+     */
+    @Nonnull
+    IWiredNetwork getNetwork();
+
+    /**
+     * Create a connection from this node to another.
+     *
+     * This should only be used on the server thread.
+     *
+     * @param node The other node to connect to.
+     * @return {@code true} if a connection was created or {@code false} if the connection already exists.
+     * @see IWiredNetwork#connect(IWiredNode, IWiredNode)
+     * @see IWiredNode#disconnectFrom(IWiredNode)
+     */
+    default boolean connectTo( @Nonnull IWiredNode node )
+    {
+        return getNetwork().connect( this, node );
+    }
+
+    /**
+     * Destroy a connection between this node and another.
+     *
+     * This should only be used on the server thread.
+     *
+     * @param node The other node to disconnect from.
+     * @return {@code true} if a connection was destroyed or {@code false} if no connection exists.
+     * @throws IllegalArgumentException If {@code node} is not on the same network.
+     * @see IWiredNetwork#disconnect(IWiredNode, IWiredNode)
+     * @see IWiredNode#connectTo(IWiredNode)
+     */
+    default boolean disconnectFrom( @Nonnull IWiredNode node )
+    {
+        return getNetwork().disconnect( this, node );
+    }
+
+    /**
+     * Sever all connections this node has, removing it from this network.
+     *
+     * This should only be used on the server thread. You should only call this on nodes
+     * that your network element owns.
+     *
+     * @return Whether this node was removed from the network. One cannot remove a node from a network where it is the
+     * only element.
+     * @throws IllegalArgumentException If the node is not in the network.
+     * @see IWiredNetwork#remove(IWiredNode)
+     */
+    default boolean remove()
+    {
+        return getNetwork().remove( this );
+    }
+
+    /**
+     * Mark this node's peripherals as having changed.
+     *
+     * This should only be used on the server thread. You should only call this on nodes
+     * that your network element owns.
+     *
+     * @param peripherals The new peripherals for this node.
+     * @see IWiredNetwork#updatePeripherals(IWiredNode, Map)
+     */
+    default void updatePeripherals( @Nonnull Map<String, IPeripheral> peripherals )
+    {
+        getNetwork().updatePeripherals( this, peripherals );
+    }
+}

src/main/java/dan200/computercraft/api/network/wired/IWiredSender.java

@@ -0,0 +1,25 @@
+package dan200.computercraft.api.network.wired;
+
+import dan200.computercraft.api.network.IPacketSender;
+
+import javax.annotation.Nonnull;
+
+/**
+ * An object on a {@link IWiredNetwork} capable of sending packets.
+ *
+ * Unlike a regular {@link IPacketSender}, this must be associated with the node you are attempting to
+ * to send the packet from.
+ */
+public interface IWiredSender extends IPacketSender
+{
+    /**
+     * The node in the network representing this object.
+     *
+     * This should be used as a proxy for the main network. One should send packets
+     * and register receivers through this object.
+     *
+     * @return The node for this element.
+     */
+    @Nonnull
+    IWiredNode getNode();
+}

src/main/java/dan200/computercraft/api/network/wired/package-info.java

@@ -0,0 +1,10 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+@API( owner="ComputerCraft", provides="ComputerCraft|API|Network|Wired", apiVersion="${version}" )
+package dan200.computercraft.api.network.wired;
+
+import net.minecraftforge.fml.common.API;

src/main/java/dan200/computercraft/api/peripheral/IComputerAccess.java

@@ -13,6 +13,8 @@ import net.minecraft.world.World;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+import java.util.Collections;
+import java.util.Map;
 
 /**
  * The interface passed to peripherals by computers or turtles, providing methods
@@ -154,4 +156,33 @@ public interface IComputerAccess
      */
     @Nonnull
     String getAttachmentName();
+
+    /**
+     * Get a set of peripherals that this computer access can "see", along with their attachment name.
+     *
+     * This may include other peripherals on the wired network or peripherals on other sides of the computer.
+     *
+     * @return All reachable peripherals
+     * @see #getAttachmentName()
+     * @see #getAvailablePeripheral(String)
+     */
+    @Nonnull
+    default Map<String, IPeripheral> getAvailablePeripherals()
+    {
+        return Collections.emptyMap();
+    }
+
+    /**
+     * Get a reachable peripheral with the given attachement name. This is a equivalent to
+     * {@link #getAvailablePeripherals()}{@code .get(name)}, though may be more performant.
+     *
+     * @param name The peripheral's attached name
+     * @return The reachable peripheral, or {@code null} if none can be found.
+     * @see #getAvailablePeripherals()
+     */
+    @Nullable
+    default IPeripheral getAvailablePeripheral( @Nonnull String name )
+    {
+        return null;
+    }
 }

src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java

@@ -114,6 +114,18 @@ public interface IPeripheral
     {
     }
 
+    /**
+     * Get the object that this peripheral provides methods for. This will generally be the tile entity
+     * or block, but may be an inventory, entity, etc...
+     *
+     * @return The object this peripheral targets
+     */
+    @Nonnull
+    default Object getTarget()
+    {
+        return this;
+    }
+
     /**
      * Determine whether this peripheral is equivalent to another one.
      *

src/main/java/dan200/computercraft/api/turtle/ITurtleAccess.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.api.turtle;
 
+import com.mojang.authlib.GameProfile;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.peripheral.IPeripheral;
@@ -135,6 +136,14 @@ public interface ITurtleAccess
      */
     int getColour();
 
+    /**
+     * Get the player who owns this turtle, namely whoever placed it.
+     *
+     * @return This turtle's owner.
+     */
+    @Nonnull
+    GameProfile getOwningPlayer();
+
     /**
      * Get the inventory of this turtle
      *
@@ -148,7 +157,7 @@ public interface ITurtleAccess
      * Get the inventory of this turtle as an {@link IItemHandlerModifiable}.
      *
      * @return This turtle's inventory
-     * @see #getInventory() 
+     * @see #getInventory()
      * @see IItemHandlerModifiable
      * @see net.minecraftforge.items.CapabilityItemHandler#ITEM_HANDLER_CAPABILITY
      */

src/main/java/dan200/computercraft/api/turtle/ITurtleUpgrade.java

@@ -8,11 +8,15 @@ package dan200.computercraft.api.turtle;
 
 import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.api.turtle.event.TurtleAttackEvent;
+import dan200.computercraft.api.turtle.event.TurtleBlockEvent;
 import net.minecraft.client.renderer.block.model.IBakedModel;
 import net.minecraft.client.renderer.block.model.ModelResourceLocation;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.ResourceLocation;
+import net.minecraftforge.event.entity.player.AttackEntityEvent;
+import net.minecraftforge.event.world.BlockEvent;
 import net.minecraftforge.fml.relauncher.Side;
 import net.minecraftforge.fml.relauncher.SideOnly;
 import org.apache.commons.lang3.tuple.Pair;
@@ -100,6 +104,9 @@ public interface ITurtleUpgrade
      * Will only be called for Tool turtle. Called when turtle.dig() or turtle.attack() is called
      * by the turtle, and the tool is required to do some work.
      *
+     * Conforming implementations should fire {@link BlockEvent.BreakEvent} and {@link TurtleBlockEvent.Dig}for digging,
+     * {@link AttackEntityEvent} and {@link TurtleAttackEvent} for attacking.
+     *
      * @param turtle    Access to the turtle that the tool resides on.
      * @param side      Which side of the turtle (left or right) the tool resides on.
      * @param verb      Which action (dig or attack) the turtle is being called on to perform.

src/main/java/dan200/computercraft/api/turtle/event/TurtleAction.java

@@ -0,0 +1,84 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+package dan200.computercraft.api.turtle.event;
+
+/**
+ * A basic action that a turtle may perform, as accessed by the {@code turtle} API.
+ *
+ * @see TurtleActionEvent
+ */
+public enum TurtleAction
+{
+    /**
+     * A turtle moves to a new position.
+     *
+     * @see TurtleBlockEvent.Move
+     */
+    MOVE,
+
+    /**
+     * A turtle turns in a specific direction.
+     */
+    TURN,
+
+    /**
+     * A turtle attempts to dig a block.
+     *
+     * @see TurtleBlockEvent.Dig
+     */
+    DIG,
+
+    /**
+     * A turtle attempts to place a block or item in the world.
+     *
+     * @see TurtleBlockEvent.Place
+     */
+    PLACE,
+
+    /**
+     * A turtle attempts to attack an entity.
+     *
+     * @see TurtleActionEvent
+     */
+    ATTACK,
+
+    /**
+     * Drop an item into an inventory/the world.
+     *
+     * @see TurtleInventoryEvent.Drop
+     */
+    DROP,
+
+    /**
+     * Suck an item from an inventory or the world.
+     *
+     * @see TurtleInventoryEvent.Suck
+     */
+    SUCK,
+
+    /**
+     * Refuel the turtle's fuel levels.
+     */
+    REFUEL,
+
+    /**
+     * Equip or unequip an item.
+     */
+    EQUIP,
+
+    /**
+     * Inspect a block in world
+     *
+     * @see TurtleBlockEvent.Inspect
+     */
+    INSPECT,
+
+    /**
+     * Gather metdata about an item in the turtle's inventory.
+     */
+    INSPECT_ITEM,
+}

src/main/java/dan200/computercraft/api/turtle/event/TurtleActionEvent.java

@@ -0,0 +1,76 @@
+package dan200.computercraft.api.turtle.event;
+
+import com.google.common.base.Preconditions;
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import dan200.computercraft.api.turtle.TurtleCommandResult;
+import net.minecraftforge.fml.common.eventhandler.Cancelable;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+/**
+ * An event fired when a turtle is performing a known action.
+ */
+@Cancelable
+public class TurtleActionEvent extends TurtleEvent
+{
+    private final TurtleAction action;
+    private String failureMessage;
+
+    public TurtleActionEvent( @Nonnull ITurtleAccess turtle, @Nonnull TurtleAction action )
+    {
+        super( turtle );
+
+        Preconditions.checkNotNull( action, "action cannot be null" );
+        this.action = action;
+    }
+
+    public TurtleAction getAction()
+    {
+        return action;
+    }
+
+    /**
+     * Sets the cancellation state of this action.
+     *
+     * If {@code cancel} is {@code true}, this action will not be carried out.
+     *
+     * @param cancel The new canceled value.
+     * @see TurtleCommandResult#failure()
+     * @deprecated Use {@link #setCanceled(boolean, String)} instead.
+     */
+    @Override
+    @Deprecated
+    public void setCanceled( boolean cancel )
+    {
+        setCanceled( cancel, null );
+    }
+
+    /**
+     * Set the cancellation state of this action, setting a failure message if required.
+     *
+     * If {@code cancel} is {@code true}, this action will not be carried out.
+     *
+     * @param cancel         The new canceled value.
+     * @param failureMessage The message to return to the user explaining the failure.
+     * @see TurtleCommandResult#failure(String)
+     */
+    public void setCanceled( boolean cancel, @Nullable String failureMessage )
+    {
+        super.setCanceled( cancel );
+        this.failureMessage = cancel ? failureMessage : null;
+    }
+
+    /**
+     * Get the message with which this will fail.
+     *
+     * @return The failure message.
+     * @see TurtleCommandResult#failure()
+     * @see #setCanceled(boolean, String)
+     */
+    @Nullable
+    public String getFailureMessage()
+    {
+        return failureMessage;
+    }
+}

src/main/java/dan200/computercraft/api/turtle/event/TurtleAttackEvent.java

@@ -0,0 +1,80 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+package dan200.computercraft.api.turtle.event;
+
+import com.google.common.base.Preconditions;
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.turtle.TurtleVerb;
+import net.minecraft.entity.Entity;
+import net.minecraft.util.EnumFacing;
+import net.minecraftforge.common.util.FakePlayer;
+import net.minecraftforge.event.entity.player.AttackEntityEvent;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Fired when a turtle attempts to attack an entity.
+ *
+ * This must be fired by {@link ITurtleUpgrade#useTool(ITurtleAccess, TurtleSide, TurtleVerb, EnumFacing)},
+ * as the base {@code turtle.attack()} command does not fire it.
+ *
+ * Note that such commands should also fire {@link AttackEntityEvent}, so you do not need to listen to both.
+ *
+ * @see TurtleAction#ATTACK
+ */
+public class TurtleAttackEvent extends TurtlePlayerEvent
+{
+    private final Entity target;
+    private final ITurtleUpgrade upgrade;
+    private final TurtleSide side;
+
+    public TurtleAttackEvent( @Nonnull ITurtleAccess turtle, @Nonnull FakePlayer player, @Nonnull Entity target, @Nonnull ITurtleUpgrade upgrade, @Nonnull TurtleSide side )
+    {
+        super( turtle, TurtleAction.ATTACK, player );
+        Preconditions.checkNotNull( target, "target cannot be null" );
+        Preconditions.checkNotNull( upgrade, "upgrade cannot be null" );
+        Preconditions.checkNotNull( side, "side cannot be null" );
+        this.target = target;
+        this.upgrade = upgrade;
+        this.side = side;
+    }
+
+    /**
+     * Get the entity being attacked by this turtle.
+     *
+     * @return The entity being attacked.
+     */
+    @Nonnull
+    public Entity getTarget()
+    {
+        return target;
+    }
+
+    /**
+     * Get the upgrade responsible for attacking.
+     *
+     * @return The upgrade responsible for attacking.
+     */
+    @Nonnull
+    public ITurtleUpgrade getUpgrade()
+    {
+        return upgrade;
+    }
+
+    /**
+     * Get the side the attacking upgrade is on.
+     *
+     * @return The upgrade's side.
+     */
+    @Nonnull
+    public TurtleSide getSide()
+    {
+        return side;
+    }
+}

src/main/java/dan200/computercraft/api/turtle/event/TurtleBlockEvent.java

@@ -0,0 +1,241 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+package dan200.computercraft.api.turtle.event;
+
+import com.google.common.base.Preconditions;
+import dan200.computercraft.api.lua.ILuaContext;
+import dan200.computercraft.api.peripheral.IComputerAccess;
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import dan200.computercraft.api.turtle.TurtleSide;
+import dan200.computercraft.api.turtle.TurtleVerb;
+import net.minecraft.block.state.IBlockState;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.EnumFacing;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.World;
+import net.minecraftforge.common.util.FakePlayer;
+import net.minecraftforge.event.world.BlockEvent;
+import net.minecraftforge.fml.common.eventhandler.Cancelable;
+
+import javax.annotation.Nonnull;
+import java.util.Map;
+
+/**
+ * A general event for when a turtle interacts with a block or region.
+ *
+ * You should generally listen to one of the sub-events instead, cancelling them where
+ * appropriate.
+ *
+ * Note that you are not guaranteed to receive this event, if it has been cancelled by other
+ * mechanisms, such as block protection systems.
+ *
+ * Be aware that some events (such as {@link TurtleInventoryEvent}) do not necessarily interact
+ * with a block, simply objects within that block space.
+ */
+@Cancelable
+public abstract class TurtleBlockEvent extends TurtlePlayerEvent
+{
+    private final World world;
+    private final BlockPos pos;
+
+    protected TurtleBlockEvent( @Nonnull ITurtleAccess turtle, @Nonnull TurtleAction action, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos )
+    {
+        super( turtle, action, player );
+
+        Preconditions.checkNotNull( world, "world cannot be null" );
+        Preconditions.checkNotNull( pos, "pos cannot be null" );
+        this.world = world;
+        this.pos = pos;
+    }
+
+    /**
+     * Get the world the turtle is interacting in.
+     *
+     * @return The world the turtle is interacting in.
+     */
+    public World getWorld()
+    {
+        return world;
+    }
+
+    /**
+     * Get the position the turtle is interacting with. Note that this is different
+     * to {@link ITurtleAccess#getPosition()}.
+     *
+     * @return The position the turtle is interacting with.
+     */
+    public BlockPos getPos()
+    {
+        return pos;
+    }
+
+    /**
+     * Fired when a turtle attempts to dig a block.
+     *
+     * This must be fired by {@link ITurtleUpgrade#useTool(ITurtleAccess, TurtleSide, TurtleVerb, EnumFacing)},
+     * as the base {@code turtle.dig()} command does not fire it.
+     *
+     * Note that such commands should also fire {@link BlockEvent.BreakEvent}, so you do not need to listen to both.
+     *
+     * @see TurtleAction#DIG
+     */
+    @Cancelable
+    public static class Dig extends TurtleBlockEvent
+    {
+        private final IBlockState block;
+        private final ITurtleUpgrade upgrade;
+        private final TurtleSide side;
+
+        public Dig( @Nonnull ITurtleAccess turtle, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos, @Nonnull IBlockState block, @Nonnull ITurtleUpgrade upgrade, @Nonnull TurtleSide side )
+        {
+            super( turtle, TurtleAction.DIG, player, world, pos );
+
+            Preconditions.checkNotNull( block, "block cannot be null" );
+            Preconditions.checkNotNull( upgrade, "upgrade cannot be null" );
+            Preconditions.checkNotNull( side, "side cannot be null" );
+            this.block = block;
+            this.upgrade = upgrade;
+            this.side = side;
+        }
+
+        /**
+         * Get the block which is about to be broken.
+         *
+         * @return The block which is going to be broken.
+         */
+        @Nonnull
+        public IBlockState getBlock()
+        {
+            return block;
+        }
+
+        /**
+         * Get the upgrade doing the digging
+         *
+         * @return The upgrade doing the digging.
+         */
+        @Nonnull
+        public ITurtleUpgrade getUpgrade()
+        {
+            return upgrade;
+        }
+
+        /**
+         * Get the side the upgrade doing the digging is on.
+         *
+         * @return The upgrade's side.
+         */
+        @Nonnull
+        public TurtleSide getSide()
+        {
+            return side;
+        }
+    }
+
+    /**
+     * Fired when a turtle attempts to move into a block.
+     *
+     * @see TurtleAction#MOVE
+     */
+    @Cancelable
+    public static class Move extends TurtleBlockEvent
+    {
+        public Move( @Nonnull ITurtleAccess turtle, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos )
+        {
+            super( turtle, TurtleAction.MOVE, player, world, pos );
+        }
+    }
+
+    /**
+     * Fired when a turtle attempts to place a block in the world.
+     *
+     * @see TurtleAction#PLACE
+     */
+    @Cancelable
+    public static class Place extends TurtleBlockEvent
+    {
+        private final ItemStack stack;
+
+        public Place( @Nonnull ITurtleAccess turtle, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos, @Nonnull ItemStack stack )
+        {
+            super( turtle, TurtleAction.PLACE, player, world, pos );
+
+            Preconditions.checkNotNull( stack, "stack cannot be null" );
+            this.stack = stack;
+        }
+
+        /**
+         * Get the item stack that will be placed. This should not be modified.
+         *
+         * @return The item stack to be placed.
+         */
+        @Nonnull
+        public ItemStack getStack()
+        {
+            return stack;
+        }
+    }
+
+    /**
+     * Fired when a turtle gathers data on a block in world.
+     *
+     * You may prevent blocks being inspected, or add additional information to the result.
+     *
+     * @see TurtleAction#INSPECT
+     */
+    @Cancelable
+    public static class Inspect extends TurtleBlockEvent
+    {
+        private final IBlockState state;
+        private final Map<String, Object> data;
+
+        public Inspect( @Nonnull ITurtleAccess turtle, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos, @Nonnull IBlockState state, @Nonnull Map<String, Object> data )
+        {
+            super( turtle, TurtleAction.INSPECT, player, world, pos );
+
+            Preconditions.checkNotNull( state, "state cannot be null" );
+            Preconditions.checkNotNull( data, "data cannot be null" );
+            this.data = data;
+            this.state = state;
+        }
+
+        /**
+         * Get the block state which is being inspected.
+         *
+         * @return The inspected block state.
+         */
+        @Nonnull
+        public IBlockState getState()
+        {
+            return state;
+        }
+
+        /**
+         * Get the "inspection data" from this block, which will be returned to the user.
+         *
+         * @return This block's inspection data.
+         */
+        @Nonnull
+        public Map<String, Object> getData()
+        {
+            return data;
+        }
+
+        /**
+         * Add new information to the inspection result. Note this will override fields with the same name.
+         *
+         * @param newData The data to add. Note all values should be convertable to Lua (see
+         *                {@link dan200.computercraft.api.peripheral.IPeripheral#callMethod(IComputerAccess, ILuaContext, int, Object[])}).
+         */
+        public void addData( @Nonnull Map<String, ?> newData )
+        {
+            Preconditions.checkNotNull( newData, "newData cannot be null" );
+            data.putAll( newData );
+        }
+    }
+}

src/main/java/dan200/computercraft/api/turtle/event/TurtleEvent.java

@@ -0,0 +1,43 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+package dan200.computercraft.api.turtle.event;
+
+import com.google.common.base.Preconditions;
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import net.minecraftforge.fml.common.eventhandler.Event;
+
+import javax.annotation.Nonnull;
+
+/**
+ * A base class for all events concerning a turtle. This will only ever constructed and fired on the server side,
+ * so sever specific methods on {@link ITurtleAccess} are safe to use.
+ *
+ * You should generally not need to subscribe to this event, preferring one of the more specific classes.
+ *
+ * @see TurtleActionEvent
+ */
+public abstract class TurtleEvent extends Event
+{
+    private final ITurtleAccess turtle;
+
+    protected TurtleEvent( @Nonnull ITurtleAccess turtle )
+    {
+        Preconditions.checkNotNull( turtle, "turtle cannot be null" );
+        this.turtle = turtle;
+    }
+
+    /**
+     * Get the turtle which is performing this action.
+     *
+     * @return The access for this turtle.
+     */
+    @Nonnull
+    public ITurtleAccess getTurtle()
+    {
+        return turtle;
+    }
+}

src/main/java/dan200/computercraft/api/turtle/event/TurtleInventoryEvent.java

@@ -0,0 +1,84 @@
+package dan200.computercraft.api.turtle.event;
+
+import com.google.common.base.Preconditions;
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.World;
+import net.minecraftforge.common.util.FakePlayer;
+import net.minecraftforge.fml.common.eventhandler.Cancelable;
+import net.minecraftforge.items.IItemHandler;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+/**
+ * Fired when a turtle attempts to interact with an inventory.
+ */
+@Cancelable
+public abstract class TurtleInventoryEvent extends TurtleBlockEvent
+{
+    private final IItemHandler handler;
+
+    protected TurtleInventoryEvent( @Nonnull ITurtleAccess turtle, @Nonnull TurtleAction action, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos, @Nullable IItemHandler handler )
+    {
+        super( turtle, action, player, world, pos );
+        this.handler = handler;
+    }
+
+    /**
+     * Get the inventory being interacted with
+     *
+     * @return The inventory being interacted with, {@code null} if the item will be dropped to/sucked from the world.
+     */
+    @Nullable
+    public IItemHandler getItemHandler()
+    {
+        return handler;
+    }
+
+    /**
+     * Fired when a turtle attempts to suck from an inventory.
+     *
+     * @see TurtleAction#SUCK
+     */
+    @Cancelable
+    public static class Suck extends TurtleInventoryEvent
+    {
+        public Suck( @Nonnull ITurtleAccess turtle, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos, @Nullable IItemHandler handler )
+        {
+            super( turtle, TurtleAction.SUCK, player, world, pos, handler );
+        }
+    }
+
+    /**
+     * Fired when a turtle attempts to drop an item into an inventory.
+     *
+     * @see TurtleAction#DROP
+     */
+    @Cancelable
+    public static class Drop extends TurtleInventoryEvent
+    {
+        private final ItemStack stack;
+
+        public Drop( @Nonnull ITurtleAccess turtle, @Nonnull FakePlayer player, @Nonnull World world, @Nonnull BlockPos pos, @Nullable IItemHandler handler, @Nonnull ItemStack stack )
+        {
+            super( turtle, TurtleAction.DROP, player, world, pos, handler );
+
+            Preconditions.checkNotNull( stack, "stack cannot be null" );
+            this.stack = stack;
+        }
+
+        /**
+         * The item which will be inserted into the inventory/dropped on the ground.
+         *
+         * Note that this is a copy of the original stack, and so should not be modified, as that will have no effect.
+         *
+         * @return The item stack which will be dropped.
+         */
+        public ItemStack getStack()
+        {
+            return stack.copy();
+        }
+    }
+}

src/main/java/dan200/computercraft/api/turtle/event/TurtlePlayerEvent.java

@@ -0,0 +1,44 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+package dan200.computercraft.api.turtle.event;
+
+import com.google.common.base.Preconditions;
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import net.minecraftforge.common.util.FakePlayer;
+
+import javax.annotation.Nonnull;
+
+/**
+ * An action done by a turtle which is normally done by a player.
+ *
+ * {@link #getPlayer()} may be used to modify the player's attributes or perform permission checks.
+ */
+public abstract class TurtlePlayerEvent extends TurtleActionEvent
+{
+    private final FakePlayer player;
+
+    protected TurtlePlayerEvent( @Nonnull ITurtleAccess turtle, @Nonnull TurtleAction action, @Nonnull FakePlayer player )
+    {
+        super( turtle, action );
+
+        Preconditions.checkNotNull( player, "player cannot be null" );
+        this.player = player;
+    }
+
+    /**
+     * A fake player, representing this turtle.
+     *
+     * This may be used for triggering permission checks.
+     *
+     * @return A {@link FakePlayer} representing this turtle.
+     */
+    @Nonnull
+    public FakePlayer getPlayer()
+    {
+        return player;
+    }
+}

src/main/java/dan200/computercraft/api/turtle/event/package-info.java

@@ -0,0 +1,10 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+@API(owner = "ComputerCraft", provides = "ComputerCraft|API|Turtle|Event", apiVersion = "${version}")
+package dan200.computercraft.api.turtle.event;
+
+import net.minecraftforge.fml.common.API;

src/main/java/dan200/computercraft/client/gui/GuiComputer.java

@@ -33,7 +33,7 @@ public class GuiComputer extends GuiContainer
     private final int m_termHeight;
     private WidgetTerminal m_terminal;
 
-    protected GuiComputer( Container container, ComputerFamily family, IComputer computer, int termWidth, int termHeight )
+    public GuiComputer( Container container, ComputerFamily family, IComputer computer, int termWidth, int termHeight )
     {
         super( container );
         m_family = family;

src/main/java/dan200/computercraft/client/gui/GuiPrintout.java

@@ -6,25 +6,19 @@
 
 package dan200.computercraft.client.gui;
 
-import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.core.terminal.TextBuffer;
 import dan200.computercraft.shared.media.inventory.ContainerHeldItem;
 import dan200.computercraft.shared.media.items.ItemPrintout;
-import dan200.computercraft.shared.util.Palette;
 import net.minecraft.client.gui.inventory.GuiContainer;
 import net.minecraft.client.renderer.GlStateManager;
-import net.minecraft.util.ResourceLocation;
 import org.lwjgl.input.Mouse;
 
 import java.io.IOException;
 
+import static dan200.computercraft.client.render.PrintoutRenderer.*;
+
 public class GuiPrintout extends GuiContainer
 {
-    private static final ResourceLocation background = new ResourceLocation( "computercraft", "textures/gui/printout.png" );
-    
-    private static final int xSize = 172;
-    private static final int ySize = 209;
-    
     private final boolean m_book;
     private final int m_pages;
     private final TextBuffer[] m_text;
@@ -34,23 +28,18 @@ public class GuiPrintout extends GuiContainer
     public GuiPrintout( ContainerHeldItem container )
     {
         super( container );
-        m_book = (ItemPrintout.getType( container.getStack() ) == ItemPrintout.Type.Book);
 
         String[] text = ItemPrintout.getText( container.getStack() );
         m_text = new TextBuffer[ text.length ];
-        for( int i=0; i<m_text.length; ++i )
-        {
-            m_text[i] = new TextBuffer( text[i] );
-        }
+        for( int i = 0; i < m_text.length; ++i ) m_text[ i ] = new TextBuffer( text[ i ] );
+
         String[] colours = ItemPrintout.getColours( container.getStack() );
         m_colours = new TextBuffer[ colours.length ];
-        for( int i=0; i<m_colours.length; ++i )
-        {
-            m_colours[i] = new TextBuffer( colours[i] );
-        }
+        for( int i = 0; i < m_colours.length; ++i ) m_colours[ i ] = new TextBuffer( colours[ i ] );
 
-        m_pages = Math.max( m_text.length / ItemPrintout.LINES_PER_PAGE, 1 );
         m_page = 0;
+        m_pages = Math.max( m_text.length / ItemPrintout.LINES_PER_PAGE, 1 );
+        m_book = ItemPrintout.getType( container.getStack() ) == ItemPrintout.Type.Book;
     }
 
     @Override
@@ -78,25 +67,19 @@ public class GuiPrintout extends GuiContainer
     }
 
     @Override
-    protected void keyTyped(char c, int k) throws IOException
+    protected void keyTyped( char c, int k ) throws IOException
     {
         super.keyTyped( c, k );
 
         if( k == 205 )
         {
             // Right
-            if( m_page < m_pages - 1 )
-            {
-                m_page = m_page + 1;
-            }
+            if( m_page < m_pages - 1 ) m_page++;
         }
         else if( k == 203 )
         {
-             // Left
-            if( m_page > 0 )
-            {
-                m_page = m_page - 1;
-            }
+            // Left
+            if( m_page > 0 ) m_page--;
         }
     }
 
@@ -106,21 +89,15 @@ public class GuiPrintout extends GuiContainer
         super.handleMouseInput();
 
         int mouseWheelChange = Mouse.getEventDWheel();
-        if (mouseWheelChange < 0)
+        if( mouseWheelChange < 0 )
         {
             // Up
-            if( m_page < m_pages - 1 )
-            {
-                m_page = m_page + 1;
-            }
+            if( m_page < m_pages - 1 ) m_page++;
         }
-        else if (mouseWheelChange > 0) 
+        else if( mouseWheelChange > 0 )
         {
             // Down
-            if( m_page > 0 )
-            {
-                m_page = m_page - 1;
-            }
+            if( m_page > 0 ) m_page--;
         }
     }
 
@@ -135,78 +112,20 @@ public class GuiPrintout extends GuiContainer
     }
 
     @Override
-    public void drawScreen(int mouseX, int mouseY, float f)
+    public void drawScreen( int mouseX, int mouseY, float f )
     {
         // Draw background
+        zLevel = zLevel - 1;
         drawDefaultBackground();
-        
+        zLevel = zLevel + 1;
+
         // Draw the printout
         GlStateManager.color( 1.0f, 1.0f, 1.0f, 1.0f );
-        this.mc.getTextureManager().bindTexture( background );
-        
-        int startY = (height - ySize) / 2;
-        //int startX = (width - xSize) / 2 - (m_page * 8);
-        int startX = (width - (xSize + (m_pages - 1)*8)) / 2;
-        
-        if( m_book )
-        {
-            // Border
-            drawTexturedModalRect( startX - 8, startY - 8, xSize + 48, 0, 12, ySize + 24);
-            drawTexturedModalRect( startX + xSize + (m_pages - 1)*8 - 4, startY - 8, xSize + 48 + 12, 0, 12, ySize + 24);
-            
-            drawTexturedModalRect( startX, startY - 8, 0, ySize, xSize, 12);
-            drawTexturedModalRect( startX, startY + ySize - 4, 0, ySize + 12, xSize, 12);
-            for( int n=1; n<m_pages; ++n )
-            {
-                drawTexturedModalRect( startX + xSize + (n-1)*8, startY - 8, 0, ySize, 8, 12);
-                drawTexturedModalRect( startX + xSize + (n-1)*8, startY + ySize - 4, 0, ySize + 12, 8, 12);
-            }
-        }
-            
-        // Left half
-        if( m_page == 0 )
-        {            
-            drawTexturedModalRect( startX, startY, 24, 0, xSize / 2, ySize);
-            drawTexturedModalRect( startX, startY, 0, 0, 12, ySize);
-        }
-        else
-        {
-            drawTexturedModalRect( startX, startY, 0, 0, 12, ySize);
-            for( int n=1; n<m_page; ++n )
-            {
-                drawTexturedModalRect( startX + n*8, startY, 12, 0, 12, ySize);                
-            }
-            drawTexturedModalRect( startX + m_page*8, startY, 24, 0, xSize / 2, ySize);
-        }
-        
-        // Right half
-        if( m_page == (m_pages - 1) )
-        {
-            drawTexturedModalRect( startX + m_page*8 + xSize/2, startY, 24 + xSize / 2, 0, xSize / 2, ySize);
-            drawTexturedModalRect( startX + m_page*8 + (xSize - 12), startY, 24 + xSize + 12, 0, 12, ySize);
-        }
-        else 
-        {
-            drawTexturedModalRect( startX + (m_pages - 1)*8 + (xSize - 12), startY, 24 + xSize + 12, 0, 12, ySize);
-            for( int n=m_pages-2; n>=m_page; --n )
-            {
-                drawTexturedModalRect( startX + n*8 + (xSize - 12), startY, 24 + xSize, 0, 12, ySize);
-            }
-            drawTexturedModalRect( startX + m_page*8 + xSize/2, startY, 24 + xSize / 2, 0, xSize / 2, ySize);
-        }
 
-        // Draw the text
-        FixedWidthFontRenderer fontRenderer = (FixedWidthFontRenderer)ComputerCraft.getFixedWidthFontRenderer();
-        int x = startX + m_page * 8 + 13;
-        int y = startY + 11;
-        for( int line=0; line<ItemPrintout.LINES_PER_PAGE; ++line )
-        {
-            int lineIdx = ItemPrintout.LINES_PER_PAGE * m_page + line;
-            if( lineIdx >= 0 && lineIdx < m_text.length )
-            {
-                fontRenderer.drawString( m_text[lineIdx], x, y, m_colours[lineIdx], null, 0, 0, false, Palette.DEFAULT );
-            }
-            y = y + FixedWidthFontRenderer.FONT_HEIGHT;
-        }
+        int startY = (height - Y_SIZE) / 2;
+        int startX = (width - X_SIZE) / 2;
+
+        drawBorder( startX, startY, zLevel, m_page, m_pages, m_book );
+        drawText( startX + X_TEXT_MARGIN, startY + Y_TEXT_MARGIN, ItemPrintout.LINES_PER_PAGE * m_page, m_text, m_colours );
     }
 }

src/main/java/dan200/computercraft/client/proxy/CCTurtleProxyClient.java

@@ -20,6 +20,7 @@ import net.minecraft.client.renderer.block.model.IBakedModel;
 import net.minecraft.client.renderer.block.model.ModelBakery;
 import net.minecraft.client.renderer.block.model.ModelResourceLocation;
 import net.minecraft.client.renderer.color.IItemColor;
+import net.minecraft.client.renderer.texture.TextureMap;
 import net.minecraft.client.renderer.vertex.DefaultVertexFormats;
 import net.minecraft.client.resources.IResourceManager;
 import net.minecraft.client.resources.SimpleReloadableResourceManager;
@@ -115,8 +116,23 @@ public class CCTurtleProxyClient extends CCTurtleProxyCommon
         MinecraftForge.EVENT_BUS.register( handlers );
     }
 
-    public class ForgeHandlers
+    public static class ForgeHandlers
     {
+        private static final String[] TURTLE_UPGRADES = {
+            "turtle_modem_off_left",
+            "turtle_modem_on_left",
+            "turtle_modem_off_right",
+            "turtle_modem_on_right",
+            "turtle_crafting_table_left",
+            "turtle_crafting_table_right",
+            "advanced_turtle_modem_off_left",
+            "advanced_turtle_modem_on_left",
+            "advanced_turtle_modem_off_right",
+            "advanced_turtle_modem_on_right",
+            "turtle_speaker_upgrade_left",
+            "turtle_speaker_upgrade_right",
+        };
+
         private TurtleSmartItemModel m_turtleSmartItemModel;
 
         public ForgeHandlers()
@@ -142,24 +158,27 @@ public class CCTurtleProxyClient extends CCTurtleProxyCommon
         @SubscribeEvent
         public void onTextureStitchEvent( TextureStitchEvent.Pre event )
         {
-            event.getMap().registerSprite( new ResourceLocation( "computercraft", "blocks/crafty_upgrade" ) );
+            // Load all textures for upgrades
+            TextureMap map = event.getMap();
+            for( String upgrade : TURTLE_UPGRADES )
+            {
+                IModel model = ModelLoaderRegistry.getModelOrMissing( new ResourceLocation( "computercraft", "block/" + upgrade ) );
+                for( ResourceLocation texture : model.getTextures() )
+                {
+                    map.registerSprite( texture );
+                }
+            }
         }
 
         @SubscribeEvent
         public void onModelBakeEvent( ModelBakeEvent event )
         {
-            loadModel( event, "turtle_modem_off_left" );
-            loadModel( event, "turtle_modem_on_left" );
-            loadModel( event, "turtle_modem_off_right" );
-            loadModel( event, "turtle_modem_on_right" );
-            loadModel( event, "turtle_crafting_table_left" );
-            loadModel( event, "turtle_crafting_table_right" );
-            loadModel( event, "advanced_turtle_modem_off_left" );
-            loadModel( event, "advanced_turtle_modem_on_left" );
-            loadModel( event, "advanced_turtle_modem_off_right" );
-            loadModel( event, "advanced_turtle_modem_on_right" );
-            loadModel( event, "turtle_speaker_upgrade_left" );
-            loadModel( event, "turtle_speaker_upgrade_right" );
+            // Load all upgrade models
+            for( String upgrade : TURTLE_UPGRADES )
+            {
+                loadModel( event, upgrade );
+            }
+
             loadSmartModel( event, "turtle_dynamic", m_turtleSmartItemModel );
         }
 
@@ -191,7 +210,7 @@ public class CCTurtleProxyClient extends CCTurtleProxyCommon
     private static class TurtleItemColour implements IItemColor
     {
         @Override
-        public int getColorFromItemstack( @Nonnull ItemStack stack, int tintIndex )
+        public int colorMultiplier( @Nonnull ItemStack stack, int tintIndex )
         {
             if( tintIndex == 0 )
             {

src/main/java/dan200/computercraft/client/proxy/ComputerCraftProxyClient.java

@@ -9,13 +9,16 @@ package dan200.computercraft.client.proxy;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.client.gui.*;
 import dan200.computercraft.client.render.ItemPocketRenderer;
+import dan200.computercraft.client.render.ItemPrintoutRenderer;
 import dan200.computercraft.client.render.RenderOverlayCable;
 import dan200.computercraft.client.render.TileEntityCableRenderer;
 import dan200.computercraft.client.render.TileEntityMonitorRenderer;
+import dan200.computercraft.shared.command.ContainerViewComputer;
 import dan200.computercraft.shared.computer.blocks.ComputerState;
 import dan200.computercraft.shared.computer.blocks.TileComputer;
 import dan200.computercraft.shared.computer.core.ClientComputer;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
+import dan200.computercraft.shared.computer.core.IComputer;
 import dan200.computercraft.shared.computer.items.ItemComputer;
 import dan200.computercraft.shared.media.inventory.ContainerHeldItem;
 import dan200.computercraft.shared.media.items.ItemDiskLegacy;
@@ -23,6 +26,7 @@ import dan200.computercraft.shared.media.items.ItemPrintout;
 import dan200.computercraft.shared.network.ComputerCraftPacket;
 import dan200.computercraft.shared.peripheral.diskdrive.TileDiskDrive;
 import dan200.computercraft.shared.peripheral.modem.TileCable;
+import dan200.computercraft.shared.peripheral.monitor.ClientMonitor;
 import dan200.computercraft.shared.peripheral.monitor.TileMonitor;
 import dan200.computercraft.shared.peripheral.printer.TilePrinter;
 import dan200.computercraft.shared.pocket.inventory.ContainerPocketComputer;
@@ -31,9 +35,10 @@ import dan200.computercraft.shared.proxy.ComputerCraftProxyCommon;
 import dan200.computercraft.shared.turtle.blocks.TileTurtle;
 import dan200.computercraft.shared.turtle.entity.TurtleVisionCamera;
 import dan200.computercraft.shared.util.Colour;
+import gnu.trove.map.hash.TIntIntHashMap;
 import net.minecraft.block.Block;
 import net.minecraft.client.Minecraft;
-import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.client.gui.GuiNewChat;
 import net.minecraft.client.renderer.ItemMeshDefinition;
 import net.minecraft.client.renderer.block.model.ModelBakery;
 import net.minecraft.client.renderer.block.model.ModelResourceLocation;
@@ -48,6 +53,7 @@ import net.minecraft.util.IThreadListener;
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.SoundEvent;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.text.ITextComponent;
 import net.minecraft.world.World;
 import net.minecraftforge.client.event.ModelRegistryEvent;
 import net.minecraftforge.client.event.RenderGameOverlayEvent;
@@ -55,6 +61,7 @@ import net.minecraftforge.client.event.RenderHandEvent;
 import net.minecraftforge.client.event.RenderPlayerEvent;
 import net.minecraftforge.client.model.ModelLoader;
 import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.event.world.WorldEvent;
 import net.minecraftforge.fml.client.registry.ClientRegistry;
 import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
 import net.minecraftforge.fml.common.gameevent.TickEvent;
@@ -68,6 +75,8 @@ import java.util.List;
 
 public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
 {
+    private static TIntIntHashMap lastCounts = new TIntIntHashMap();
+
     private long m_tick;
     private long m_renderFrame;
     private FixedWidthFontRenderer m_fixedWidthFontRenderer;
@@ -113,6 +122,7 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
         registerItemModel( ComputerCraft.Blocks.commandComputer, "command_computer" );
         registerItemModel( ComputerCraft.Blocks.advancedModem, "advanced_modem" );
         registerItemModel( ComputerCraft.Blocks.peripheral, 5, "speaker" );
+        registerItemModel( ComputerCraft.Blocks.wiredModemFull, "wired_modem_full" );
 
         registerItemModel( ComputerCraft.Items.disk, "disk" );
         registerItemModel( ComputerCraft.Items.diskExpanded, "disk_expanded" );
@@ -294,12 +304,6 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
         return m_renderFrame;
     }
 
-    @Override
-    public void deleteDisplayLists( int list, int range )
-    {
-        GlStateManager.glDeleteLists( list, range );
-    }
-
     @Override
     public Object getFixedWidthFontRenderer()
     {
@@ -364,6 +368,13 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
         return null;
     }
 
+    @Override
+    public Object getComputerGUI( IComputer computer, int width, int height, ComputerFamily family )
+    {
+        ContainerViewComputer container = new ContainerViewComputer( computer );
+        return new GuiComputer( container, family, computer, width, height );
+    }
+
     @Override
     public File getWorldDir( World world )
     {
@@ -379,6 +390,7 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
             case ComputerCraftPacket.ComputerTerminalChanged:
             case ComputerCraftPacket.ComputerDeleted:
             case ComputerCraftPacket.PlayRecord:
+            case ComputerCraftPacket.PostChat:
             {
                 // Packet from Server to Client
                 IThreadListener listener = Minecraft.getMinecraft();
@@ -445,6 +457,36 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
                 {
                     mc.world.playRecord( pos, null );
                 }
+                break;
+            }
+            case ComputerCraftPacket.PostChat:
+            {
+                /*
+                  This allows us to send delete chat messages of the same "category" as the previous one.
+                  It's used by the various /computercraft commands to avoid filling the chat with repetitive
+                  messages.
+                 */
+
+                int id = packet.m_dataInt[0];
+                ITextComponent[] components = new ITextComponent[packet.m_dataString.length];
+                for( int i = 0; i < packet.m_dataString.length; i++ )
+                {
+                    components[i] = ITextComponent.Serializer.jsonToComponent( packet.m_dataString[i] );
+                }
+
+                GuiNewChat chat = Minecraft.getMinecraft().ingameGUI.getChatGUI();
+
+                // Keep track of how many lines we wrote last time, deleting any extra ones.
+                int lastCount = lastCounts.get( id );
+                for( int i = components.length; i < lastCount; i++ ) chat.deleteChatLine( i + id );
+                lastCounts.put( id, components.length );
+
+                // Add new lines
+                for( int i = 0; i < components.length; i++ )
+                {
+                    chat.printChatMessageWithOptionalDeletion( components[i], id + i );
+                }
+                break;
             }
 
         }
@@ -456,6 +498,7 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
         MinecraftForge.EVENT_BUS.register( handlers );
         MinecraftForge.EVENT_BUS.register( new RenderOverlayCable() );
         MinecraftForge.EVENT_BUS.register( new ItemPocketRenderer() );
+        MinecraftForge.EVENT_BUS.register( new ItemPrintoutRenderer() );
     }
 
     public class ForgeHandlers
@@ -542,6 +585,15 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
                 m_renderFrame++;
             }
         }
+
+        @SubscribeEvent
+        public void onWorldUnload( WorldEvent.Unload event )
+        {
+            if( event.getWorld().isRemote )
+            {
+                ClientMonitor.destroyAll();
+            }
+        }
     }
 
     @SideOnly(Side.CLIENT)
@@ -555,7 +607,7 @@ public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
         }
 
         @Override
-        public int getColorFromItemstack( @Nonnull ItemStack stack, int layer )
+        public int colorMultiplier( @Nonnull ItemStack stack, int layer )
         {
             return layer == 0 ? 0xFFFFFF : disk.getColour( stack );
         }

src/main/java/dan200/computercraft/client/render/ItemPrintoutRenderer.java

@@ -0,0 +1,197 @@
+package dan200.computercraft.client.render;
+
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.media.items.ItemPrintout;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.client.renderer.ItemRenderer;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.EnumHand;
+import net.minecraft.util.EnumHandSide;
+import net.minecraft.util.math.MathHelper;
+import net.minecraftforge.client.event.RenderItemInFrameEvent;
+import net.minecraftforge.client.event.RenderSpecificHandEvent;
+import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
+
+import static dan200.computercraft.client.gui.FixedWidthFontRenderer.FONT_HEIGHT;
+import static dan200.computercraft.client.gui.FixedWidthFontRenderer.FONT_WIDTH;
+import static dan200.computercraft.client.render.PrintoutRenderer.*;
+import static dan200.computercraft.shared.media.items.ItemPrintout.LINES_PER_PAGE;
+import static dan200.computercraft.shared.media.items.ItemPrintout.LINE_MAX_LENGTH;
+
+public class ItemPrintoutRenderer
+{
+    @SubscribeEvent
+    public void onRenderInHand( RenderSpecificHandEvent event )
+    {
+        ItemStack stack = event.getItemStack();
+        if( stack.getItem() != ComputerCraft.Items.printout ) return;
+
+        event.setCanceled( true );
+
+        EntityPlayer player = Minecraft.getMinecraft().player;
+
+        GlStateManager.pushMatrix();
+        if( event.getHand() == EnumHand.MAIN_HAND && player.getHeldItemOffhand().isEmpty() )
+        {
+            renderPrintoutFirstPersonCentre(
+                event.getInterpolatedPitch(),
+                event.getEquipProgress(),
+                event.getSwingProgress(),
+                stack
+            );
+        }
+        else
+        {
+            renderPrintoutFirstPersonSide(
+                event.getHand() == EnumHand.MAIN_HAND ? player.getPrimaryHand() : player.getPrimaryHand().opposite(),
+                event.getEquipProgress(),
+                event.getSwingProgress(),
+                stack
+            );
+        }
+        GlStateManager.popMatrix();
+    }
+
+    /**
+     * Renders a pocket computer to one side of the player.
+     *
+     * @param side          The side to render on
+     * @param equipProgress The equip progress of this item
+     * @param swingProgress The swing progress of this item
+     * @param stack         The stack to render
+     * @see ItemRenderer#renderMapFirstPersonSide(float, EnumHandSide, float, ItemStack)
+     */
+    private void renderPrintoutFirstPersonSide( EnumHandSide side, float equipProgress, float swingProgress, ItemStack stack )
+    {
+        Minecraft minecraft = Minecraft.getMinecraft();
+        float offset = side == EnumHandSide.RIGHT ? 1f : -1f;
+        GlStateManager.translate( offset * 0.125f, -0.125f, 0f );
+
+        // If the player is not invisible then render a single arm
+        if( !minecraft.player.isInvisible() )
+        {
+            GlStateManager.pushMatrix();
+            GlStateManager.rotate( offset * 10f, 0f, 0f, 1f );
+            minecraft.getItemRenderer().renderArmFirstPerson( equipProgress, swingProgress, side );
+            GlStateManager.popMatrix();
+        }
+
+        // Setup the appropriate transformations. This is just copied from the
+        // corresponding method in ItemRenderer. 
+        GlStateManager.pushMatrix();
+        GlStateManager.translate( offset * 0.51f, -0.08f + equipProgress * -1.2f, -0.75f );
+        float f1 = MathHelper.sqrt( swingProgress );
+        float f2 = MathHelper.sin( f1 * (float) Math.PI );
+        float f3 = -0.5f * f2;
+        float f4 = 0.4f * MathHelper.sin( f1 * ((float) Math.PI * 2f) );
+        float f5 = -0.3f * MathHelper.sin( swingProgress * (float) Math.PI );
+        GlStateManager.translate( offset * f3, f4 - 0.3f * f2, f5 );
+        GlStateManager.rotate( f2 * -45f, 1f, 0f, 0f );
+        GlStateManager.rotate( offset * f2 * -30f, 0f, 1f, 0f );
+
+        renderPrintoutFirstPerson( stack );
+
+        GlStateManager.popMatrix();
+    }
+
+    /**
+     * Render an item in the middle of the screen
+     *
+     * @param pitch         The pitch of the player
+     * @param equipProgress The equip progress of this item
+     * @param swingProgress The swing progress of this item
+     * @param stack         The stack to render
+     * @see ItemRenderer#renderMapFirstPerson(float, float, float)
+     */
+    private void renderPrintoutFirstPersonCentre( float pitch, float equipProgress, float swingProgress, ItemStack stack )
+    {
+        ItemRenderer itemRenderer = Minecraft.getMinecraft().getItemRenderer();
+
+        // Setup the appropriate transformations. This is just copied from the
+        // corresponding method in ItemRenderer.
+        float swingRt = MathHelper.sqrt( swingProgress );
+        float tX = -0.2f * MathHelper.sin( swingProgress * (float) Math.PI );
+        float tZ = -0.4f * MathHelper.sin( swingRt * (float) Math.PI );
+        GlStateManager.translate( 0f, -tX / 2f, tZ );
+        float pitchAngle = itemRenderer.getMapAngleFromPitch( pitch );
+        GlStateManager.translate( 0f, 0.04f + equipProgress * -1.2f + pitchAngle * -0.5f, -0.72f );
+        GlStateManager.rotate( pitchAngle * -85f, 1f, 0f, 0f );
+        itemRenderer.renderArms();
+        float rX = MathHelper.sin( swingRt * (float) Math.PI );
+        GlStateManager.rotate( rX * 20f, 1f, 0f, 0f );
+        GlStateManager.scale( 2f, 2f, 2f );
+
+        renderPrintoutFirstPerson( stack );
+    }
+
+
+    private static void renderPrintoutFirstPerson( ItemStack stack )
+    {
+        // Setup various transformations. Note that these are partially adapated from the corresponding method
+        // in ItemRenderer.renderMapFirstPerson
+        GlStateManager.disableLighting();
+
+        GlStateManager.rotate( 180f, 0f, 1f, 0f );
+        GlStateManager.rotate( 180f, 0f, 0f, 1f );
+        GlStateManager.scale( 0.42f, 0.42f, -0.42f );
+        GlStateManager.translate( -0.5f, -0.48f, 0.0f );
+
+        drawPrintout( stack );
+
+        GlStateManager.enableLighting();
+    }
+
+    @SubscribeEvent
+    public void onRenderInFrame( RenderItemInFrameEvent event )
+    {
+        ItemStack stack = event.getItem();
+        if( stack.getItem() != ComputerCraft.Items.printout ) return;
+
+        event.setCanceled( true );
+
+        GlStateManager.disableLighting();
+
+        // Move a little bit forward to ensure we're not clipping with the frame
+        GlStateManager.translate( 0.0f, 0.0f, -0.001f );
+        GlStateManager.rotate( 180f, 0f, 0f, 1f );
+        GlStateManager.scale( 0.95f, 0.95f, -0.95f );
+        GlStateManager.translate( -0.5f, -0.5f, 0.0f );
+
+        drawPrintout( stack );
+
+        GlStateManager.enableLighting();
+    }
+
+    private static void drawPrintout( ItemStack stack )
+    {
+        int pages = ItemPrintout.getPageCount( stack );
+        boolean book = ItemPrintout.getType( stack ) == ItemPrintout.Type.Book;
+
+        double width = LINE_MAX_LENGTH * FONT_WIDTH + X_TEXT_MARGIN * 2;
+        double height = LINES_PER_PAGE * FONT_HEIGHT + Y_TEXT_MARGIN * 2;
+
+        // Non-books will be left aligned
+        if( !book ) width += offsetAt( pages );
+
+        double visualWidth = width, visualHeight = height;
+
+        // Meanwhile books will be centred
+        if( book )
+        {
+            visualWidth += 2 * COVER_SIZE + 2 * offsetAt( pages );
+            visualHeight += 2 * COVER_SIZE;
+        }
+
+        double max = Math.max( visualHeight, visualWidth );
+
+        // Scale the printout to fit correctly.
+        double scale = 1.0 / max;
+        GlStateManager.scale( scale, scale, scale );
+        GlStateManager.translate( (max - width) / 2.0f, (max - height) / 2.0f, 0.0f );
+
+        drawBorder( 0, 0, -0.01, 0, pages, book );
+        drawText( X_TEXT_MARGIN, Y_TEXT_MARGIN, 0, ItemPrintout.getText( stack ), ItemPrintout.getColours( stack ) );
+    }
+}

src/main/java/dan200/computercraft/client/render/ModelTransformer.java

@@ -189,7 +189,7 @@ public final class ModelTransformer
         private BakedQuadBuilder( VertexFormat format )
         {
             this.format = format;
-            this.vertexData = new int[ format.getNextOffset() ];
+            this.vertexData = new int[ format.getSize() ];
         }
 
         @Nonnull

src/main/java/dan200/computercraft/client/render/PrintoutRenderer.java

@@ -0,0 +1,169 @@
+package dan200.computercraft.client.render;
+
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.client.gui.FixedWidthFontRenderer;
+import dan200.computercraft.core.terminal.TextBuffer;
+import dan200.computercraft.shared.util.Palette;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.BufferBuilder;
+import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.client.renderer.Tessellator;
+import net.minecraft.client.renderer.vertex.DefaultVertexFormats;
+import net.minecraft.util.ResourceLocation;
+import org.lwjgl.opengl.GL11;
+
+import static dan200.computercraft.client.gui.FixedWidthFontRenderer.FONT_HEIGHT;
+import static dan200.computercraft.shared.media.items.ItemPrintout.LINES_PER_PAGE;
+
+public class PrintoutRenderer
+{
+    private static final ResourceLocation BG = new ResourceLocation( "computercraft", "textures/gui/printout.png" );
+    private static final double BG_SIZE = 256.0;
+
+    /**
+     * Width of a page
+     */
+    public static final int X_SIZE = 172;
+
+    /**
+     * Height of a page
+     */
+    public static final int Y_SIZE = 209;
+
+    /**
+     * Padding between the left and right of a page and the text
+     */
+    public static final int X_TEXT_MARGIN = 13;
+
+    /**
+     * Padding between the top and bottom of a page and the text
+     */
+    public static final int Y_TEXT_MARGIN = 11;
+
+    /**
+     * Width of the extra page texture
+     */
+    private static final int X_FOLD_SIZE = 12;
+
+    /**
+     * Size of the leather cover
+     */
+    public static final int COVER_SIZE = 12;
+
+    private static final int COVER_Y = Y_SIZE;
+    private static final int COVER_X = X_SIZE + 4 * X_FOLD_SIZE;
+
+    public static void drawText( int x, int y, int start, TextBuffer[] text, TextBuffer[] colours )
+    {
+        FixedWidthFontRenderer fontRenderer = (FixedWidthFontRenderer) ComputerCraft.getFixedWidthFontRenderer();
+
+        for( int line = 0; line < LINES_PER_PAGE && line < text.length; ++line )
+        {
+            fontRenderer.drawString( text[ start + line ], x, y + line * FONT_HEIGHT, colours[ start + line ], null, 0, 0, false, Palette.DEFAULT );
+        }
+    }
+
+    public static void drawText( int x, int y, int start, String[] text, String[] colours )
+    {
+        GlStateManager.color( 1.0f, 1.0f, 1.0f, 1.0f );
+        GlStateManager.enableBlend();
+        GlStateManager.enableTexture2D();
+
+        FixedWidthFontRenderer fontRenderer = (FixedWidthFontRenderer) ComputerCraft.getFixedWidthFontRenderer();
+
+        for( int line = 0; line < LINES_PER_PAGE && line < text.length; ++line )
+        {
+            fontRenderer.drawString( new TextBuffer( text[ start + line ] ), x, y + line * FONT_HEIGHT, new TextBuffer( colours[ start + line ] ), null, 0, 0, false, Palette.DEFAULT );
+        }
+    }
+
+    public static void drawBorder( double x, double y, double z, int page, int pages, boolean isBook )
+    {
+        GlStateManager.color( 1.0f, 1.0f, 1.0f, 1.0f );
+        GlStateManager.enableBlend();
+        GlStateManager.enableTexture2D();
+
+        Minecraft.getMinecraft().getTextureManager().bindTexture( BG );
+
+        Tessellator tessellator = Tessellator.getInstance();
+        BufferBuilder buffer = tessellator.getBuffer();
+        buffer.begin( GL11.GL_QUADS, DefaultVertexFormats.POSITION_TEX );
+
+        int leftPages = page;
+        int rightPages = pages - page - 1;
+
+        if( isBook )
+        {
+            // Border
+            double offset = offsetAt( pages );
+            final double left = x - 4 - offset;
+            final double right = x + X_SIZE + offset - 4;
+
+            // Left and right border
+            drawTexture( buffer, left - 4, y - 8, z - 0.02, COVER_X, 0, COVER_SIZE, Y_SIZE + COVER_SIZE * 2 );
+            drawTexture( buffer, right, y - 8, z - 0.02, COVER_X + COVER_SIZE, 0, COVER_SIZE, Y_SIZE + COVER_SIZE * 2 );
+
+            // Draw centre panel (just stretched texture, sorry).
+            drawTexture( buffer,
+                x - offset, y, z - 0.02, X_SIZE + offset * 2, Y_SIZE,
+                COVER_X + COVER_SIZE / 2, COVER_SIZE, COVER_SIZE, Y_SIZE
+            );
+
+            double borderX = left;
+            while( borderX < right )
+            {
+                double thisWidth = Math.min( right - borderX, X_SIZE );
+                drawTexture( buffer, borderX, y - 8, z - 0.02, 0, COVER_Y, thisWidth, COVER_SIZE );
+                drawTexture( buffer, borderX, y + Y_SIZE - 4, z - 0.02, 0, COVER_Y + COVER_SIZE, thisWidth, COVER_SIZE );
+                borderX += thisWidth;
+            }
+        }
+
+        // Left half
+        drawTexture( buffer, x, y, z, X_FOLD_SIZE * 2, 0, X_SIZE / 2, Y_SIZE );
+        for( int n = 0; n <= leftPages; n++ )
+        {
+            drawTexture( buffer,
+                x - offsetAt( n ), y, z - 1e-3 * n,
+                // Use the left "bold" fold for the outermost page
+                n == leftPages ? 0 : X_FOLD_SIZE, 0,
+                X_FOLD_SIZE, Y_SIZE
+            );
+        }
+
+        // Right half
+        drawTexture( buffer, x + X_SIZE / 2, y, z, X_FOLD_SIZE * 2 + X_SIZE / 2, 0, X_SIZE / 2, Y_SIZE );
+        for( int n = 0; n <= rightPages; n++ )
+        {
+            drawTexture( buffer,
+                x + (X_SIZE - X_FOLD_SIZE) + offsetAt( n ), y, z - 1e-3 * n,
+                // Two folds, then the main page. Use the right "bold" fold for the outermost page.
+                X_FOLD_SIZE * 2 + X_SIZE + (n == rightPages ? X_FOLD_SIZE : 0), 0,
+                X_FOLD_SIZE, Y_SIZE
+            );
+        }
+
+        tessellator.draw();
+    }
+
+    private static void drawTexture( BufferBuilder buffer, double x, double y, double z, double u, double v, double width, double height )
+    {
+        buffer.pos( x, y + height, z ).tex( u / BG_SIZE, (v + height) / BG_SIZE ).endVertex();
+        buffer.pos( x + width, y + height, z ).tex( (u + width) / BG_SIZE, (v + height) / BG_SIZE ).endVertex();
+        buffer.pos( x + width, y, z ).tex( (u + width) / BG_SIZE, v / BG_SIZE ).endVertex();
+        buffer.pos( x, y, z ).tex( u / BG_SIZE, v / BG_SIZE ).endVertex();
+    }
+
+    private static void drawTexture( BufferBuilder buffer, double x, double y, double z, double width, double height, double u, double v, double tWidth, double tHeight )
+    {
+        buffer.pos( x, y + height, z ).tex( u / BG_SIZE, (v + tHeight) / BG_SIZE ).endVertex();
+        buffer.pos( x + width, y + height, z ).tex( (u + tWidth) / BG_SIZE, (v + tHeight) / BG_SIZE ).endVertex();
+        buffer.pos( x + width, y, z ).tex( (u + tWidth) / BG_SIZE, v / BG_SIZE ).endVertex();
+        buffer.pos( x, y, z ).tex( u / BG_SIZE, v / BG_SIZE ).endVertex();
+    }
+
+    public static double offsetAt( int page )
+    {
+        return 32 * (1 - Math.pow( 1.2, -page ));
+    }
+}

src/main/java/dan200/computercraft/client/render/RenderOverlayCable.java

@@ -54,8 +54,6 @@ public class RenderOverlayCable
         GlStateManager.depthMask( false );
         GlStateManager.pushMatrix();
 
-        EnumFacing direction = type != PeripheralType.Cable ? cable.getDirection() : null;
-
         {
             EntityPlayer player = event.getPlayer();
             double x = player.lastTickPosX + (player.posX - player.lastTickPosX) * event.getPartialTicks();
@@ -78,7 +76,7 @@ public class RenderOverlayCable
 
             for( EnumFacing facing : EnumFacing.VALUES )
             {
-                if( direction == facing || BlockCable.isCable( world, pos.offset( facing ) ) )
+                if( BlockCable.doesConnectVisually( state, world, pos, facing ) )
                 {
                     flags |= 1 << facing.ordinal();
 

src/main/java/dan200/computercraft/client/render/TileEntityCableRenderer.java

@@ -71,7 +71,7 @@ public class TileEntityCableRenderer extends TileEntitySpecialRenderer<TileCable
         buffer.setTranslation( x - pos.getX(), y - pos.getY(), z - pos.getZ() );
         buffer.noColor();
 
-        ForgeHooksClient.setRenderLayer( block.getBlockLayer() );
+        ForgeHooksClient.setRenderLayer( block.getRenderLayer() );
 
         // See BlockRendererDispatcher#renderBlockDamage
         TextureAtlasSprite breakingTexture = mc.getTextureMapBlocks().getAtlasSprite( "minecraft:blocks/destroy_stage_" + destroyStage );

src/main/java/dan200/computercraft/client/render/TileEntityMonitorRenderer.java

@@ -10,7 +10,7 @@ import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.client.gui.FixedWidthFontRenderer;
 import dan200.computercraft.core.terminal.Terminal;
 import dan200.computercraft.core.terminal.TextBuffer;
-import dan200.computercraft.shared.common.ClientTerminal;
+import dan200.computercraft.shared.peripheral.monitor.ClientMonitor;
 import dan200.computercraft.shared.peripheral.monitor.TileMonitor;
 import dan200.computercraft.shared.util.Colour;
 import dan200.computercraft.shared.util.DirectionUtil;
@@ -18,6 +18,7 @@ import dan200.computercraft.shared.util.Palette;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.renderer.BufferBuilder;
 import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.client.renderer.OpenGlHelper;
 import net.minecraft.client.renderer.Tessellator;
 import net.minecraft.client.renderer.tileentity.TileEntitySpecialRenderer;
 import net.minecraft.client.renderer.vertex.DefaultVertexFormats;
@@ -43,25 +44,24 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
     private void renderMonitorAt( TileMonitor monitor, double posX, double posY, double posZ, float f, int i )
     {
         // Render from the origin monitor
-        TileMonitor origin = monitor.getOrigin();
-        if( origin == null )
-        {
-            return;
-        }
+        ClientMonitor originTerminal = monitor.getClientMonitor();
 
-        // Ensure each monitor is rendered only once
-        long renderFrame = ComputerCraft.getRenderFrame();
-        if( origin.m_lastRenderFrame == renderFrame )
-        {
-            return;
-        }
-        else
-        {
-            origin.m_lastRenderFrame = renderFrame;
-        }
-
-        boolean redraw = origin.pollChanged();
+        if( originTerminal == null ) return;
+        TileMonitor origin = originTerminal.getOrigin();
         BlockPos monitorPos = monitor.getPos();
+
+        // Ensure each monitor terminal is rendered only once. We allow rendering a specific tile
+        // multiple times in a single frame to ensure compatibility with shaders which may run a 
+        // pass multiple times.
+        long renderFrame = ComputerCraft.getRenderFrame();
+        if( originTerminal.lastRenderFrame == renderFrame && !monitorPos.equals( originTerminal.lastRenderPos ) )
+        {
+            return;
+        }
+
+        originTerminal.lastRenderFrame = renderFrame;
+        originTerminal.lastRenderPos = monitorPos;
+
         BlockPos originPos = origin.getPos();
         posX += originPos.getX() - monitorPos.getX();
         posY += originPos.getY() - monitorPos.getY();
@@ -94,34 +94,34 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
             BufferBuilder renderer = tessellator.getBuffer();
 
             // Get terminal
-            ClientTerminal clientTerminal = (ClientTerminal)origin.getTerminal();
-            Terminal terminal = (clientTerminal != null) ? clientTerminal.getTerminal() : null;
-            redraw = redraw || (clientTerminal != null && clientTerminal.hasTerminalChanged());
+            boolean redraw = originTerminal.pollTerminalChanged();
 
             // Draw the contents
             GlStateManager.depthMask( false );
+            OpenGlHelper.setLightmapTextureCoords( OpenGlHelper.lightmapTexUnit, 0xFF, 0xFF );
             GlStateManager.disableLighting();
             mc.entityRenderer.disableLightmap();
             try
             {
+                Terminal terminal = originTerminal.getTerminal();
                 if( terminal != null )
                 {
                     Palette palette = terminal.getPalette();
 
                     // Allocate display lists
-                    if( origin.m_renderDisplayList < 0 )
+                    if( originTerminal.renderDisplayLists == null )
                     {
-                        origin.m_renderDisplayList = GlStateManager.glGenLists( 3 );
+                        originTerminal.createLists();
                         redraw = true;
                     }
 
                     // Draw a terminal
-                    boolean greyscale = !clientTerminal.isColour();
+                    boolean greyscale = !originTerminal.isColour();
                     int width = terminal.getWidth();
                     int height = terminal.getHeight();
                     int cursorX = terminal.getCursorX();
                     int cursorY = terminal.getCursorY();
-                    FixedWidthFontRenderer fontRenderer = (FixedWidthFontRenderer)ComputerCraft.getFixedWidthFontRenderer();
+                    FixedWidthFontRenderer fontRenderer = (FixedWidthFontRenderer) ComputerCraft.getFixedWidthFontRenderer();
 
                     GlStateManager.pushMatrix();
                     try
@@ -135,7 +135,7 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
                         if( redraw )
                         {
                             // Build background display list
-                            GlStateManager.glNewList( origin.m_renderDisplayList, GL11.GL_COMPILE );
+                            GlStateManager.glNewList( originTerminal.renderDisplayLists[0], GL11.GL_COMPILE );
                             try
                             {
                                 double marginXSize = TileMonitor.RENDER_MARGIN / xScale;
@@ -149,7 +149,7 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
                                     GlStateManager.scale( 1.0, marginSquash, 1.0 );
                                     GlStateManager.translate( 0.0, -marginYSize / marginSquash, 0.0 );
                                     fontRenderer.drawStringBackgroundPart( 0, 0, terminal.getBackgroundColourLine( 0 ), marginXSize, marginXSize, greyscale, palette );
-                                    GlStateManager.translate( 0.0, ( marginYSize + height * FixedWidthFontRenderer.FONT_HEIGHT ) / marginSquash, 0.0 );
+                                    GlStateManager.translate( 0.0, (marginYSize + height * FixedWidthFontRenderer.FONT_HEIGHT) / marginSquash, 0.0 );
                                     fontRenderer.drawStringBackgroundPart( 0, 0, terminal.getBackgroundColourLine( height - 1 ), marginXSize, marginXSize, greyscale, palette );
                                 }
                                 finally
@@ -174,7 +174,7 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
                                 GlStateManager.glEndList();
                             }
                         }
-                        GlStateManager.callList( origin.m_renderDisplayList );
+                        GlStateManager.callList( originTerminal.renderDisplayLists[0] );
                         GlStateManager.resetColor();
 
                         // Draw text
@@ -182,7 +182,7 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
                         if( redraw )
                         {
                             // Build text display list
-                            GlStateManager.glNewList( origin.m_renderDisplayList + 1, GL11.GL_COMPILE );
+                            GlStateManager.glNewList( originTerminal.renderDisplayLists[1], GL11.GL_COMPILE );
                             try
                             {
                                 // Lines
@@ -202,7 +202,7 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
                                 GlStateManager.glEndList();
                             }
                         }
-                        GlStateManager.callList( origin.m_renderDisplayList + 1 );
+                        GlStateManager.callList( originTerminal.renderDisplayLists[1] );
                         GlStateManager.resetColor();
 
                         // Draw cursor
@@ -210,7 +210,7 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
                         if( redraw )
                         {
                             // Build cursor display list
-                            GlStateManager.glNewList( origin.m_renderDisplayList + 2, GL11.GL_COMPILE );
+                            GlStateManager.glNewList( originTerminal.renderDisplayLists[2], GL11.GL_COMPILE );
                             try
                             {
                                 // Cursor
@@ -236,7 +236,7 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
                         }
                         if( ComputerCraft.getGlobalCursorBlink() )
                         {
-                            GlStateManager.callList( origin.m_renderDisplayList + 2 );
+                            GlStateManager.callList( originTerminal.renderDisplayLists[2] );
                             GlStateManager.resetColor();
                         }
                     }

src/main/java/dan200/computercraft/client/render/TurtleSmartItemModel.java

@@ -167,7 +167,7 @@ public class TurtleSmartItemModel implements IBakedModel, IResourceManagerReload
         ModelResourceLocation baseModelLocation = TileEntityTurtleRenderer.getTurtleModel( combo.m_family, combo.m_colour );
         ModelResourceLocation overlayModelLocation = TileEntityTurtleRenderer.getTurtleOverlayModel( combo.m_family, combo.m_overlay, combo.m_christmas );
         IBakedModel baseModel = modelManager.getModel( baseModelLocation );
-        IBakedModel overlayModel = (overlayModelLocation != null) ? modelManager.getModel( baseModelLocation ) : null;
+        IBakedModel overlayModel = (overlayModelLocation != null) ? modelManager.getModel( overlayModelLocation ) : null;
         Matrix4f transform = combo.m_flip ? s_flip : s_identity;
         Pair<IBakedModel, Matrix4f> leftModel = (combo.m_leftUpgrade != null) ? combo.m_leftUpgrade.getModel( null, TurtleSide.Left ) : null;
         Pair<IBakedModel, Matrix4f> rightModel = (combo.m_rightUpgrade != null) ? combo.m_rightUpgrade.getModel( null, TurtleSide.Right ) : null;

src/main/java/dan200/computercraft/core/apis/ComputerAccess.java

@@ -3,14 +3,17 @@ package dan200.computercraft.core.apis;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
 import dan200.computercraft.api.peripheral.IComputerAccess;
+import dan200.computercraft.core.computer.Computer;
+import dan200.computercraft.core.computer.IComputerOwned;
 import dan200.computercraft.core.filesystem.FileSystem;
 import dan200.computercraft.core.filesystem.FileSystemException;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import java.util.HashSet;
 import java.util.Set;
 
-public abstract class ComputerAccess implements IComputerAccess
+public abstract class ComputerAccess implements IComputerAccess, IComputerOwned
 {
     private final IAPIEnvironment m_environment;
     private final Set<String> m_mounts = new HashSet<>();
@@ -133,6 +136,13 @@ public abstract class ComputerAccess implements IComputerAccess
         m_environment.queueEvent( event, arguments );
     }
 
+    @Nullable
+    @Override
+    public Computer getComputer()
+    {
+        return m_environment.getComputer();
+    }
+
     private String findFreeLocation( String desiredLoc )
     {
         try

src/main/java/dan200/computercraft/core/apis/FSAPI.java

@@ -9,18 +9,23 @@ package dan200.computercraft.core.apis;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
-import dan200.computercraft.core.apis.handles.BinaryInputHandle;
-import dan200.computercraft.core.apis.handles.BinaryOutputHandle;
-import dan200.computercraft.core.apis.handles.EncodedInputHandle;
-import dan200.computercraft.core.apis.handles.EncodedOutputHandle;
+import dan200.computercraft.core.apis.handles.BinaryReadableHandle;
+import dan200.computercraft.core.apis.handles.BinaryWritableHandle;
+import dan200.computercraft.core.apis.handles.EncodedReadableHandle;
+import dan200.computercraft.core.apis.handles.EncodedWritableHandle;
 import dan200.computercraft.core.filesystem.FileSystem;
 import dan200.computercraft.core.filesystem.FileSystemException;
+import dan200.computercraft.core.filesystem.FileSystemWrapper;
+import dan200.computercraft.core.tracking.TrackingField;
 
 import javax.annotation.Nonnull;
-import java.io.InputStream;
-import java.io.OutputStream;
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.channels.WritableByteChannel;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.function.Function;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.getString;
 
@@ -88,6 +93,7 @@ public class FSAPI implements ILuaAPI
             {
                 // list
                 String path = getString( args, 0 );
+                m_env.addTrackingChange( TrackingField.FS_OPS );
                 try {
                     String[] results = m_fileSystem.list( path );
                     Map<Object,Object> table = new HashMap<>();
@@ -162,6 +168,7 @@ public class FSAPI implements ILuaAPI
                 // makeDir
                 String path = getString( args, 0 );
                 try {
+                    m_env.addTrackingChange( TrackingField.FS_OPS );
                     m_fileSystem.makeDir( path );
                     return null;
                 } catch( FileSystemException e ) {
@@ -174,6 +181,7 @@ public class FSAPI implements ILuaAPI
                 String path = getString( args, 0 );
                 String dest = getString( args, 1 );
                 try {
+                    m_env.addTrackingChange( TrackingField.FS_OPS );
                     m_fileSystem.move( path, dest );
                     return null;
                 } catch( FileSystemException e ) {
@@ -186,6 +194,7 @@ public class FSAPI implements ILuaAPI
                 String path = getString( args, 0 );
                 String dest = getString( args, 1 );
                 try {
+                    m_env.addTrackingChange( TrackingField.FS_OPS );
                     m_fileSystem.copy( path, dest );
                     return null;
                 } catch( FileSystemException e ) {
@@ -197,6 +206,7 @@ public class FSAPI implements ILuaAPI
                 // delete
                 String path = getString( args, 0 );
                 try {
+                    m_env.addTrackingChange( TrackingField.FS_OPS );
                     m_fileSystem.delete( path );
                     return null;
                 } catch( FileSystemException e ) {
@@ -208,44 +218,45 @@ public class FSAPI implements ILuaAPI
                 // open
                 String path = getString( args, 0 );
                 String mode = getString( args, 1 );
+                m_env.addTrackingChange( TrackingField.FS_OPS );
                 try {
                     switch( mode )
                     {
                         case "r":
                         {
                             // Open the file for reading, then create a wrapper around the reader
-                            InputStream reader = m_fileSystem.openForRead( path );
-                            return new Object[] { new EncodedInputHandle( reader ) };
+                            FileSystemWrapper<BufferedReader> reader = m_fileSystem.openForRead( path, EncodedReadableHandle::openUtf8 );
+                            return new Object[] { new EncodedReadableHandle( reader.get(), reader ) };
                         }
                         case "w":
                         {
                             // Open the file for writing, then create a wrapper around the writer
-                            OutputStream writer = m_fileSystem.openForWrite( path, false );
-                            return new Object[] { new EncodedOutputHandle( writer ) };
+                            FileSystemWrapper<BufferedWriter> writer = m_fileSystem.openForWrite( path, false, EncodedWritableHandle::openUtf8 );
+                            return new Object[] { new EncodedWritableHandle( writer.get(), writer ) };
                         }
                         case "a":
                         {
                             // Open the file for appending, then create a wrapper around the writer
-                            OutputStream writer = m_fileSystem.openForWrite( path, true );
-                            return new Object[] { new EncodedOutputHandle( writer ) };
+                            FileSystemWrapper<BufferedWriter> writer = m_fileSystem.openForWrite( path, true, EncodedWritableHandle::openUtf8 );
+                            return new Object[] { new EncodedWritableHandle( writer.get(), writer ) };
                         }
                         case "rb":
                         {
                             // Open the file for binary reading, then create a wrapper around the reader
-                            InputStream reader = m_fileSystem.openForRead( path );
-                            return new Object[] { new BinaryInputHandle( reader ) };
+                            FileSystemWrapper<ReadableByteChannel> reader = m_fileSystem.openForRead( path, Function.identity() );
+                            return new Object[] { new BinaryReadableHandle( reader.get(), reader ) };
                         }
                         case "wb":
                         {
                             // Open the file for binary writing, then create a wrapper around the writer
-                            OutputStream writer = m_fileSystem.openForWrite( path, false );
-                            return new Object[] { new BinaryOutputHandle( writer ) };
+                            FileSystemWrapper<WritableByteChannel> writer = m_fileSystem.openForWrite( path, false, Function.identity() );
+                            return new Object[] { new BinaryWritableHandle( writer.get(), writer ) };
                         }
                         case "ab":
                         {
                             // Open the file for binary appending, then create a wrapper around the reader
-                            OutputStream writer = m_fileSystem.openForWrite( path, true );
-                            return new Object[] { new BinaryOutputHandle( writer ) };
+                            FileSystemWrapper<WritableByteChannel> writer = m_fileSystem.openForWrite( path, true, Function.identity() );
+                            return new Object[] { new BinaryWritableHandle( writer.get(), writer ) };
                         }
                         default:
                             throw new LuaException( "Unsupported mode" );
@@ -288,6 +299,7 @@ public class FSAPI implements ILuaAPI
                 // find
                 String path = getString( args, 0 );
                 try {
+                    m_env.addTrackingChange( TrackingField.FS_OPS );
                     String[] results = m_fileSystem.find( path );
                     Map<Object,Object> table = new HashMap<>();
                     for(int i=0; i<results.length; ++i ) {

src/main/java/dan200/computercraft/core/apis/HTTPAPI.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.core.apis;
 
+import com.google.common.collect.ImmutableSet;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.ILuaContext;
@@ -21,9 +22,14 @@ import java.util.*;
 import java.util.concurrent.Future;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.core.apis.TableHelper.*;
 
 public class HTTPAPI implements ILuaAPI
 {
+    private static final Set<String> HTTP_METHODS = ImmutableSet.of(
+        "GET", "POST", "HEAD", "OPTIONS", "PUT", "DELETE"
+    );
+
     private final IAPIEnvironment m_apiEnvironment;
     private final List<Future<?>> m_httpTasks;
     private final Set<Closeable> m_closeables;
@@ -38,7 +44,7 @@ public class HTTPAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
+        return new String[]{
             "http"
         };
     }
@@ -59,7 +65,7 @@ public class HTTPAPI implements ILuaAPI
     }
 
     @Override
-    public void shutdown( )
+    public void shutdown()
     {
         synchronized( m_httpTasks )
         {
@@ -89,7 +95,7 @@ public class HTTPAPI implements ILuaAPI
     @Override
     public String[] getMethodNames()
     {
-        return new String[] {
+        return new String[]{
             "request",
             "checkURL",
             "websocket",
@@ -101,52 +107,68 @@ public class HTTPAPI implements ILuaAPI
     {
         switch( method )
         {
-            case 0:
+            case 0: // request
             {
-                // request
-                // Get URL
-                String urlString = getString( args, 0 );
+                String urlString, postString, requestMethod;
+                Map<Object, Object> headerTable;
+                boolean binary, redirect;
 
-                // Get POST
-                String postString = optString( args, 1, null );
-
-                // Get Headers
-                Map<String, String> headers = null;
-                Map<Object, Object> table = optTable( args, 2, null );
-                if( table != null )
+                if( args.length >= 1 && args[0] instanceof Map )
                 {
-                    headers = new HashMap<>( table.size() );
-                    for( Object key : table.keySet() )
+                    Map<?, ?> options = (Map) args[0];
+                    urlString = getStringField( options, "url" );
+                    postString = optStringField( options, "body", null );
+                    headerTable = optTableField( options, "headers", null );
+                    binary = optBooleanField( options, "binary", false );
+                    requestMethod = optStringField( options, "method", null );
+                    redirect = optBooleanField( options, "redirect", true );
+
+                }
+                else
+                {
+                    // Get URL and post information
+                    urlString = getString( args, 0 );
+                    postString = optString( args, 1, null );
+                    headerTable = optTable( args, 2, null );
+                    binary = optBoolean( args, 3, false );
+                    requestMethod = null;
+                    redirect = true;
+                }
+
+                Map<String, String> headers = null;
+                if( headerTable != null )
+                {
+                    headers = new HashMap<>( headerTable.size() );
+                    for( Object key : headerTable.keySet() )
                     {
-                        Object value = table.get( key );
+                        Object value = headerTable.get( key );
                         if( key instanceof String && value instanceof String )
                         {
-                            headers.put( (String)key, (String)value );
+                            headers.put( (String) key, (String) value );
                         }
                     }
                 }
 
-                // Get binary
-                boolean binary = false;
-                if( args.length >= 4 )
+
+                if( requestMethod != null && !HTTP_METHODS.contains( requestMethod ) )
                 {
-                    binary = args[ 3 ] != null && !args[ 3 ].equals( Boolean.FALSE );
+                    throw new LuaException( "Unsupported HTTP method" );
                 }
 
                 // Make the request
                 try
                 {
                     URL url = HTTPRequest.checkURL( urlString );
-                    HTTPRequest request = new HTTPRequest( m_apiEnvironment, urlString, url, postString, headers, binary );
+                    HTTPRequest request = new HTTPRequest( m_apiEnvironment, urlString, url, postString, headers, binary, requestMethod, redirect );
                     synchronized( m_httpTasks )
                     {
                         m_httpTasks.add( HTTPExecutor.EXECUTOR.submit( request ) );
                     }
-                    return new Object[] { true };
+                    return new Object[]{ true };
                 }
                 catch( HTTPRequestException e )
                 {
-                    return new Object[] { false, e.getMessage() };
+                    return new Object[]{ false, e.getMessage() };
                 }
             }
             case 1:
@@ -164,11 +186,11 @@ public class HTTPAPI implements ILuaAPI
                     {
                         m_httpTasks.add( HTTPExecutor.EXECUTOR.submit( check ) );
                     }
-                    return new Object[] { true };
+                    return new Object[]{ true };
                 }
                 catch( HTTPRequestException e )
                 {
-                    return new Object[] { false, e.getMessage() };
+                    return new Object[]{ false, e.getMessage() };
                 }
             }
             case 2: // websocket
@@ -201,11 +223,11 @@ public class HTTPAPI implements ILuaAPI
                     {
                         m_httpTasks.add( connector );
                     }
-                    return new Object[] { true };
+                    return new Object[]{ true };
                 }
                 catch( HTTPRequestException e )
                 {
-                    return new Object[] { false, e.getMessage() };
+                    return new Object[]{ false, e.getMessage() };
                 }
             }
             default:

src/main/java/dan200/computercraft/core/apis/IAPIEnvironment.java

@@ -9,16 +9,19 @@ package dan200.computercraft.core.apis;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.computer.Computer;
 import dan200.computercraft.core.computer.IComputerEnvironment;
+import dan200.computercraft.core.computer.IComputerOwned;
 import dan200.computercraft.core.filesystem.FileSystem;
 import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.core.tracking.TrackingField;
 
-public interface IAPIEnvironment
+public interface IAPIEnvironment extends IComputerOwned
 {
     interface IPeripheralChangeListener
     {
         void onPeripheralChanged( int side, IPeripheral newPeripheral );
     }
-    
+
+    @Override
     Computer getComputer();
     int getComputerID();
     IComputerEnvironment getComputerEnvironment();
@@ -42,4 +45,11 @@ public interface IAPIEnvironment
 
     String getLabel();
     void setLabel( String label );
+
+    void addTrackingChange( TrackingField field, long change );
+
+    default void addTrackingChange( TrackingField field )
+    {
+        addTrackingChange( field, 1 );
+    }
 }

src/main/java/dan200/computercraft/core/apis/ILuaAPI.java

@@ -0,0 +1,16 @@
+package dan200.computercraft.core.apis;
+
+/**
+ * This exists purely to ensure binary compatibility.
+ *
+ * @see dan200.computercraft.api.lua.ILuaAPI
+ */
+public interface ILuaAPI extends dan200.computercraft.api.lua.ILuaAPI
+{
+    void advance( double v );
+
+    default void update()
+    {
+        advance( 0.05 );
+    }
+}

src/main/java/dan200/computercraft/core/apis/PeripheralAPI.java

@@ -15,10 +15,12 @@ import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.computer.Computer;
 import dan200.computercraft.core.computer.ComputerThread;
 import dan200.computercraft.core.computer.ITask;
-import dan200.computercraft.core.filesystem.FileSystem;
+import dan200.computercraft.core.tracking.TrackingField;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -108,6 +110,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             }
             if( method >= 0 )
             {
+                m_environment.addTrackingChange( TrackingField.PERIPHERAL_OPS );
                 return m_peripheral.callMethod( this, context, method, arguments );
             }
             else
@@ -180,10 +183,49 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             }
             return m_side;
         }
+
+        @Nonnull
+        @Override
+        public Map<String, IPeripheral> getAvailablePeripherals()
+        {
+            if( !m_attached )
+            {
+                throw new RuntimeException( "You are not attached to this Computer" );
+            }
+
+            Map<String, IPeripheral> peripherals = new HashMap<>();
+            for( PeripheralWrapper wrapper : m_peripherals )
+            {
+                if( wrapper != null && wrapper.isAttached() )
+                {
+                    peripherals.put( wrapper.getAttachmentName(), wrapper.getPeripheral() );
+                }
+            }
+
+            return Collections.unmodifiableMap( peripherals );
+        }
+
+        @Nullable
+        @Override
+        public IPeripheral getAvailablePeripheral( @Nonnull String name )
+        {
+            if( !m_attached )
+            {
+                throw new RuntimeException( "You are not attached to this Computer" );
+            }
+
+            for( PeripheralWrapper wrapper : m_peripherals )
+            {
+                if( wrapper != null && wrapper.isAttached() && wrapper.getAttachmentName().equals( name ) )
+                {
+                    return wrapper.getPeripheral();
+                }
+            }
+            return null;
+        }
     }
 
     private final IAPIEnvironment m_environment;
-    private FileSystem m_fileSystem;
     private final PeripheralWrapper[] m_peripherals;
     private boolean m_running;
 
@@ -285,7 +327,6 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
     {
         synchronized( m_peripherals )
         {
-            m_fileSystem = m_environment.getFileSystem();
             m_running = true;
             for( int i=0; i<6; ++i )
             {
@@ -312,7 +353,6 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
                     wrapper.detach();
                 }
             }
-            m_fileSystem = null;
         }
     }
 

src/main/java/dan200/computercraft/core/apis/TableHelper.java

@@ -0,0 +1,214 @@
+package dan200.computercraft.core.apis;
+
+import dan200.computercraft.api.lua.LuaException;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.Map;
+
+/**
+ * Various helpers for tables
+ */
+public final class TableHelper
+{
+    private TableHelper()
+    {
+        throw new IllegalStateException( "Cannot instantiate singleton " + getClass().getName() );
+    }
+
+    @Nonnull
+    public static LuaException badKey( @Nonnull String key, @Nonnull String expected, @Nullable Object actual )
+    {
+        return badKey( key, expected, ArgumentHelper.getType( actual ) );
+    }
+
+    @Nonnull
+    public static LuaException badKey( @Nonnull String key, @Nonnull String expected, @Nonnull String actual )
+    {
+        return new LuaException( "bad field '" + key + "' (" + expected + " expected, got " + actual + ")" );
+    }
+
+    public static double getNumberField( @Nonnull Map<?, ?> table, @Nonnull String key ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value instanceof Number )
+        {
+            return ((Number) value).doubleValue();
+        }
+        else
+        {
+            throw badKey( key, "number", value );
+        }
+    }
+
+    public static int getIntField( @Nonnull Map<?, ?> table, @Nonnull String key ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value instanceof Number )
+        {
+            return (int) ((Number) value).longValue();
+        }
+        else
+        {
+            throw badKey( key, "number", value );
+        }
+    }
+
+    public static double getRealField( @Nonnull Map<?, ?> table, @Nonnull String key ) throws LuaException
+    {
+        return checkReal( key, getNumberField( table, key ) );
+    }
+
+    public static boolean getBooleanField( @Nonnull Map<?, ?> table, @Nonnull String key ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value instanceof Boolean )
+        {
+            return (Boolean) value;
+        }
+        else
+        {
+            throw badKey( key, "boolean", value );
+        }
+    }
+
+    @Nonnull
+    public static String getStringField( @Nonnull Map<?, ?> table, @Nonnull String key ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value instanceof String )
+        {
+            return (String) value;
+        }
+        else
+        {
+            throw badKey( key, "string", value );
+        }
+    }
+
+    @SuppressWarnings( "unchecked" )
+    @Nonnull
+    public static Map<Object, Object> getTableField( @Nonnull Map<?, ?> table, @Nonnull String key ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value instanceof Map )
+        {
+            return (Map<Object, Object>) value;
+        }
+        else
+        {
+            throw badKey( key, "table", value );
+        }
+    }
+
+    public static double optNumberField( @Nonnull Map<?, ?> table, @Nonnull String key, double def ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value == null )
+        {
+            return def;
+        }
+        else if( value instanceof Number )
+        {
+            return ((Number) value).doubleValue();
+        }
+        else
+        {
+            throw badKey( key, "number", value );
+        }
+    }
+
+    public static int optIntField( @Nonnull Map<?, ?> table, @Nonnull String key, int def ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value == null )
+        {
+            return def;
+        }
+        else if( value instanceof Number )
+        {
+            return (int) ((Number) value).longValue();
+        }
+        else
+        {
+            throw badKey( key, "number", value );
+        }
+    }
+
+    public static double optRealField( @Nonnull Map<?, ?> table, @Nonnull String key, double def ) throws LuaException
+    {
+        return checkReal( key, optNumberField( table, key, def ) );
+    }
+
+    public static boolean optBooleanField( @Nonnull Map<?, ?> table, @Nonnull String key, boolean def ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value == null )
+        {
+            return def;
+        }
+        else if( value instanceof Boolean )
+        {
+            return (Boolean) value;
+        }
+        else
+        {
+            throw badKey( key, "boolean", value );
+        }
+    }
+
+    public static String optStringField( @Nonnull Map<?, ?> table, @Nonnull String key, String def ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value == null )
+        {
+            return def;
+        }
+        else if( value instanceof String )
+        {
+            return (String) value;
+        }
+        else
+        {
+            throw badKey( key, "string", value );
+        }
+    }
+
+    @SuppressWarnings( "unchecked" )
+    public static Map<Object, Object> optTableField( @Nonnull Map<?, ?> table, @Nonnull String key, Map<Object, Object> def ) throws LuaException
+    {
+        Object value = table.get( key );
+        if( value == null )
+        {
+            return def;
+        }
+        else if( value instanceof Map )
+        {
+            return (Map<Object, Object>) value;
+        }
+        else
+        {
+            throw badKey( key, "table", value );
+        }
+    }
+
+    private static double checkReal( @Nonnull String key, double value ) throws LuaException
+    {
+        if( Double.isNaN( value ) )
+        {
+            throw badKey( key, "number", "nan" );
+        }
+        else if( value == Double.POSITIVE_INFINITY )
+        {
+            throw badKey( key, "number", "inf" );
+        }
+        else if( value == Double.NEGATIVE_INFINITY )
+        {
+            throw badKey( key, "number", "-inf" );
+        }
+        else
+        {
+            return value;
+        }
+    }
+}

src/main/java/dan200/computercraft/core/apis/TermAPI.java

@@ -64,7 +64,8 @@ public class TermAPI implements ILuaAPI
             "setPaletteColour",
             "setPaletteColor",
             "getPaletteColour",
-            "getPaletteColor"
+            "getPaletteColor",
+            "getCursorBlink",
         };
     }
     
@@ -284,6 +285,9 @@ public class TermAPI implements ILuaAPI
                 }
                 return null;
             }
+            case 23:
+                // getCursorBlink
+                return new Object[] { m_terminal.getCursorBlink() };
             default:
             {
                 return null;

src/main/java/dan200/computercraft/core/apis/handles/ArrayByteChannel.java

@@ -0,0 +1,91 @@
+package dan200.computercraft.core.apis.handles;
+
+import com.google.common.base.Preconditions;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.NonWritableChannelException;
+import java.nio.channels.SeekableByteChannel;
+
+/**
+ * A seekable, readable byte channel which is backed by a simple byte array.
+ */
+public class ArrayByteChannel implements SeekableByteChannel
+{
+    private boolean closed = false;
+    private int position = 0;
+
+    private final byte[] backing;
+
+    public ArrayByteChannel( byte[] backing )
+    {
+        this.backing = backing;
+    }
+
+    @Override
+    public int read( ByteBuffer destination ) throws IOException
+    {
+        if( closed ) throw new ClosedChannelException();
+        Preconditions.checkNotNull( destination, "destination" );
+
+        if( position >= backing.length ) return -1;
+
+        int remaining = Math.min( backing.length - position, destination.remaining() );
+        destination.put( backing, position, remaining );
+        position += remaining;
+        return remaining;
+    }
+
+    @Override
+    public int write( ByteBuffer src ) throws IOException
+    {
+        if( closed ) throw new ClosedChannelException();
+        throw new NonWritableChannelException();
+    }
+
+    @Override
+    public long position() throws IOException
+    {
+        if( closed ) throw new ClosedChannelException();
+        return position;
+    }
+
+    @Override
+    public SeekableByteChannel position( long newPosition ) throws IOException
+    {
+        if( closed ) throw new ClosedChannelException();
+        if( newPosition < 0 || newPosition > Integer.MAX_VALUE )
+        {
+            throw new IllegalArgumentException( "Position out of bounds" );
+        }
+        position = (int) newPosition;
+        return this;
+    }
+
+    @Override
+    public long size() throws IOException
+    {
+        if( closed ) throw new ClosedChannelException();
+        return backing.length;
+    }
+
+    @Override
+    public SeekableByteChannel truncate( long size ) throws IOException
+    {
+        if( closed ) throw new ClosedChannelException();
+        throw new NonWritableChannelException();
+    }
+
+    @Override
+    public boolean isOpen()
+    {
+        return !closed;
+    }
+
+    @Override
+    public void close()
+    {
+        closed = true;
+    }
+}

src/main/java/dan200/computercraft/core/apis/handles/BinaryInputHandle.java

@@ -1,89 +0,0 @@
-package dan200.computercraft.core.apis.handles;
-
-import com.google.common.io.ByteStreams;
-import dan200.computercraft.api.lua.ILuaContext;
-import dan200.computercraft.api.lua.LuaException;
-
-import javax.annotation.Nonnull;
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.Arrays;
-
-import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
-
-public class BinaryInputHandle extends HandleGeneric
-{
-    private final InputStream m_stream;
-
-    public BinaryInputHandle( InputStream reader )
-    {
-        super( reader );
-        this.m_stream = reader;
-    }
-
-    @Nonnull
-    @Override
-    public String[] getMethodNames()
-    {
-        return new String[] {
-            "read",
-            "readAll",
-            "close",
-        };
-    }
-
-    @Override
-    public Object[] callMethod( @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
-    {
-        switch( method )
-        {
-            case 0:
-                // read
-                checkOpen();
-                try
-                {
-                    if( args.length > 0 && args[ 0 ] != null )
-                    {
-                        int count = getInt( args, 0 );
-                        if( count <= 0 || count >= 1024 * 16 )
-                        {
-                            throw new LuaException( "Count out of range" );
-                        }
-
-                        byte[] bytes = new byte[ count ];
-                        count = m_stream.read( bytes );
-                        if( count < 0 ) return null;
-                        if( count < bytes.length ) bytes = Arrays.copyOf( bytes, count );
-                        return new Object[] { bytes };
-                    }
-                    else
-                    {
-                        int b = m_stream.read();
-                        return b == -1 ? null : new Object[] { b };
-                    }
-                }
-                catch( IOException e )
-                {
-                    return null;
-                }
-            case 1:
-                // readAll
-                checkOpen();
-                try
-                {
-                    byte[] out = ByteStreams.toByteArray( m_stream );
-                    return out == null ? null : new Object[] { out };
-                }
-                catch( IOException e )
-                {
-                    return null;
-                }
-            case 2:
-                //close
-                close();
-                return null;
-            default:
-                return null;
-        }
-    }
-}

src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java

@@ -0,0 +1,205 @@
+package dan200.computercraft.core.apis.handles;
+
+import com.google.common.collect.ObjectArrays;
+import dan200.computercraft.api.lua.ILuaContext;
+import dan200.computercraft.api.lua.LuaException;
+
+import javax.annotation.Nonnull;
+import java.io.ByteArrayOutputStream;
+import java.io.Closeable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.channels.SeekableByteChannel;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
+import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
+
+public class BinaryReadableHandle extends HandleGeneric
+{
+    private static final int BUFFER_SIZE = 8192;
+
+    private static final String[] METHOD_NAMES = new String[] { "read", "readAll", "readLine", "close" };
+    private static final String[] METHOD_SEEK_NAMES = ObjectArrays.concat( METHOD_NAMES, new String[] { "seek" }, String.class );
+
+    private final ReadableByteChannel m_reader;
+    private final SeekableByteChannel m_seekable;
+    private final ByteBuffer single = ByteBuffer.allocate( 1 );
+
+    public BinaryReadableHandle( ReadableByteChannel channel, Closeable closeable )
+    {
+        super( closeable );
+        this.m_reader = channel;
+        this.m_seekable = channel instanceof SeekableByteChannel ? (SeekableByteChannel) channel : null;
+    }
+
+    public BinaryReadableHandle( ReadableByteChannel channel )
+    {
+        this( channel, channel );
+    }
+
+    @Nonnull
+    @Override
+    public String[] getMethodNames()
+    {
+        return m_seekable == null ? METHOD_NAMES : METHOD_SEEK_NAMES;
+    }
+
+    @Override
+    public Object[] callMethod( @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
+    {
+        switch( method )
+        {
+            case 0:
+                // read
+                checkOpen();
+                try
+                {
+                    if( args.length > 0 && args[ 0 ] != null )
+                    {
+                        int count = getInt( args, 0 );
+                        if( count < 0 )
+                        {
+                            throw new LuaException( "Cannot read a negative number of bytes" );
+                        }
+                        else if( count == 0 && m_seekable != null )
+                        {
+                            return m_seekable.position() >= m_seekable.size() ? null : new Object[] { "" };
+                        }
+
+                        if( count <= BUFFER_SIZE )
+                        {
+                            ByteBuffer buffer = ByteBuffer.allocate( count );
+                            
+                            int read = m_reader.read( buffer );
+                            if( read < 0 ) return null;
+                            return new Object[] { read < count ? Arrays.copyOf( buffer.array(), read ) : buffer.array() };
+                        }
+                        else
+                        {
+                            ByteBuffer buffer = ByteBuffer.allocate( BUFFER_SIZE );
+
+                            int read = m_reader.read( buffer );
+                            if( read < 0 ) return null;
+                            int totalRead = read;
+
+                            // If we failed to read "enough" here, let's just abort
+                            if( totalRead >= count || read < BUFFER_SIZE )
+                            {
+                                return new Object[] { Arrays.copyOf( buffer.array(), read ) };
+                            }
+
+                            // Build up an array of ByteBuffers. Hopefully this means we can perform less allocation 
+                            // than doubling up the buffer each time.
+                            List<ByteBuffer> parts = new ArrayList<>( 4 );
+                            parts.add( buffer );
+                            while( totalRead < count && read >= BUFFER_SIZE )
+                            {
+                                buffer = ByteBuffer.allocate( BUFFER_SIZE );
+                                totalRead += read = m_reader.read( buffer );
+                                parts.add( buffer );
+                            }
+
+                            // Now just copy all the bytes across!
+                            byte[] bytes = new byte[ totalRead ];
+                            int pos = 0;
+                            for( ByteBuffer part : parts )
+                            {
+                                System.arraycopy( part.array(), 0, bytes, pos, part.position() );
+                                pos += part.position();
+                            }
+                            return new Object[] { bytes };
+                        }
+                    }
+                    else
+                    {
+                        single.clear();
+                        int b = m_reader.read( single );
+                        return b == -1 ? null : new Object[] { single.get( 0 ) };
+                    }
+                }
+                catch( IOException e )
+                {
+                    return null;
+                }
+            case 1:
+                // readAll
+                checkOpen();
+                try
+                {
+                    int expected = 32;
+                    if( m_seekable != null )
+                    {
+                        expected = Math.max( expected, (int) (m_seekable.size() - m_seekable.position()) );
+                    }
+                    ByteArrayOutputStream stream = new ByteArrayOutputStream( expected );
+
+                    ByteBuffer buf = ByteBuffer.allocate( 8192 );
+                    boolean readAnything = false;
+                    while( true )
+                    {
+                        buf.clear();
+                        int r = m_reader.read( buf );
+                        if( r == -1 ) break;
+
+                        readAnything = true;
+                        stream.write( buf.array(), 0, r );
+                    }
+                    return readAnything ? new Object[] { stream.toByteArray() } : null;
+                }
+                catch( IOException e )
+                {
+                    return null;
+                }
+            case 2:
+            {
+                // readLine
+                checkOpen();
+                boolean withTrailing = optBoolean( args, 0, false );
+                try
+                {
+                    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+
+                    boolean readAnything = false;
+                    while( true )
+                    {
+                        single.clear();
+                        int r = m_reader.read( single );
+                        if( r == -1 ) break;
+
+                        readAnything = true;
+                        byte b = single.get( 0 );
+                        if( b == '\n' )
+                        {
+                            if( withTrailing ) stream.write( b );
+                            break;
+                        }
+                        else
+                        {
+                            stream.write( b );
+                        }
+                    }
+
+                    return readAnything ? new Object[] { stream.toByteArray() } : null;
+                }
+                catch( IOException e )
+                {
+                    return null;
+                }
+            }
+            case 3:
+                //close
+                close();
+                return null;
+            case 4:
+                // seek
+                checkOpen();
+                return handleSeek( m_seekable, args );
+            default:
+                return null;
+        }
+    }
+}

src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java

@@ -1,33 +1,45 @@
 package dan200.computercraft.core.apis.handles;
 
+import com.google.common.collect.ObjectArrays;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.core.apis.ArgumentHelper;
 import dan200.computercraft.shared.util.StringUtil;
 
 import javax.annotation.Nonnull;
+import java.io.Closeable;
 import java.io.IOException;
-import java.io.OutputStream;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.channels.SeekableByteChannel;
+import java.nio.channels.WritableByteChannel;
 
-public class BinaryOutputHandle extends HandleGeneric
+public class BinaryWritableHandle extends HandleGeneric
 {
-    private final OutputStream m_writer;
+    private static final String[] METHOD_NAMES = new String[] { "write", "flush", "close" };
+    private static final String[] METHOD_SEEK_NAMES = ObjectArrays.concat( METHOD_NAMES, new String[] { "seek" }, String.class );
 
-    public BinaryOutputHandle( OutputStream writer )
+    private final WritableByteChannel m_writer;
+    private final SeekableByteChannel m_seekable;
+    private final ByteBuffer single = ByteBuffer.allocate( 1 );
+
+    public BinaryWritableHandle( WritableByteChannel channel, Closeable closeable )
     {
-        super( writer );
-        this.m_writer = writer;
+        super( closeable );
+        this.m_writer = channel;
+        this.m_seekable = channel instanceof SeekableByteChannel ? (SeekableByteChannel) channel : null;
+    }
+
+    public BinaryWritableHandle( WritableByteChannel channel )
+    {
+        this( channel, channel );
     }
 
     @Nonnull
     @Override
     public String[] getMethodNames()
     {
-        return new String[] {
-            "write",
-            "flush",
-            "close",
-        };
+        return m_seekable == null ? METHOD_NAMES : METHOD_SEEK_NAMES;
     }
 
     @Override
@@ -43,12 +55,16 @@ public class BinaryOutputHandle extends HandleGeneric
                     if( args.length > 0 && args[ 0 ] instanceof Number )
                     {
                         int number = ((Number) args[ 0 ]).intValue();
-                        m_writer.write( number );
+                        single.clear();
+                        single.put( (byte) number );
+                        single.flip();
+
+                        m_writer.write( single );
                     }
                     else if( args.length > 0 && args[ 0 ] instanceof String )
                     {
                         String value = (String) args[ 0 ];
-                        m_writer.write( StringUtil.encodeString( value ) );
+                        m_writer.write( ByteBuffer.wrap( StringUtil.encodeString( value ) ) );
                     }
                     else
                     {
@@ -65,7 +81,9 @@ public class BinaryOutputHandle extends HandleGeneric
                 checkOpen();
                 try
                 {
-                    m_writer.flush();
+                    // Technically this is not needed
+                    if( m_writer instanceof FileChannel ) ((FileChannel) m_writer).force( false );
+
                     return null;
                 }
                 catch( IOException e )
@@ -76,6 +94,10 @@ public class BinaryOutputHandle extends HandleGeneric
                 //close
                 close();
                 return null;
+            case 3:
+                // seek
+                checkOpen();
+                return handleSeek( m_seekable, args );
             default:
                 return null;
         }

src/main/java/dan200/computercraft/core/apis/handles/EncodedInputHandle.java

@@ -1,132 +0,0 @@
-package dan200.computercraft.core.apis.handles;
-
-import dan200.computercraft.api.lua.ILuaContext;
-import dan200.computercraft.api.lua.LuaException;
-
-import javax.annotation.Nonnull;
-import java.io.*;
-
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
-
-public class EncodedInputHandle extends HandleGeneric
-{
-    private final BufferedReader m_reader;
-
-    public EncodedInputHandle( BufferedReader reader )
-    {
-        super( reader );
-        this.m_reader = reader;
-    }
-
-    public EncodedInputHandle( InputStream stream )
-    {
-        this( stream, "UTF-8" );
-    }
-
-    public EncodedInputHandle( InputStream stream, String encoding )
-    {
-        this( makeReader( stream, encoding ) );
-    }
-
-    private static BufferedReader makeReader( InputStream stream, String encoding )
-    {
-        if( encoding == null ) encoding = "UTF-8";
-        InputStreamReader streamReader;
-        try
-        {
-            streamReader = new InputStreamReader( stream, encoding );
-        }
-        catch( UnsupportedEncodingException e )
-        {
-            streamReader = new InputStreamReader( stream );
-        }
-        return new BufferedReader( streamReader );
-    }
-
-    @Nonnull
-    @Override
-    public String[] getMethodNames()
-    {
-        return new String[] {
-            "readLine",
-            "readAll",
-            "close",
-            "read",
-        };
-    }
-
-    @Override
-    public Object[] callMethod( @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
-    {
-        switch( method )
-        {
-            case 0:
-                // readLine
-                checkOpen();
-                try
-                {
-                    String line = m_reader.readLine();
-                    if( line != null )
-                    {
-                        return new Object[] { line };
-                    }
-                    else
-                    {
-                        return null;
-                    }
-                }
-                catch( IOException e )
-                {
-                    return null;
-                }
-            case 1:
-                // readAll
-                checkOpen();
-                try
-                {
-                    StringBuilder result = new StringBuilder( "" );
-                    String line = m_reader.readLine();
-                    while( line != null )
-                    {
-                        result.append( line );
-                        line = m_reader.readLine();
-                        if( line != null )
-                        {
-                            result.append( "\n" );
-                        }
-                    }
-                    return new Object[] { result.toString() };
-                }
-                catch( IOException e )
-                {
-                    return null;
-                }
-            case 2:
-                // close
-                close();
-                return null;
-            case 3:
-                // read
-                checkOpen();
-                try
-                {
-                    int count = optInt( args, 0, 1 );
-                    if( count <= 0 || count >= 1024 * 16 )
-                    {
-                        throw new LuaException( "Count out of range" );
-                    }
-                    char[] bytes = new char[ count ];
-                    count = m_reader.read( bytes );
-                    if( count < 0 ) return null;
-                    String str = new String( bytes, 0, count );
-                    return new Object[] { str };
-                }
-                catch( IOException e )
-                {
-                    return null;
-                }
-            default:
-                return null;
-        }
-    }
-}

src/main/java/dan200/computercraft/core/apis/handles/EncodedReadableHandle.java

@@ -0,0 +1,165 @@
+package dan200.computercraft.core.apis.handles;
+
+import dan200.computercraft.api.lua.ILuaContext;
+import dan200.computercraft.api.lua.LuaException;
+
+import javax.annotation.Nonnull;
+import java.io.BufferedReader;
+import java.io.Closeable;
+import java.io.IOException;
+import java.nio.channels.Channels;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
+import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
+import static dan200.computercraft.core.apis.ArgumentHelper.optInt;
+
+public class EncodedReadableHandle extends HandleGeneric
+{
+    private static final int BUFFER_SIZE = 8192;
+
+    private BufferedReader m_reader;
+
+    public EncodedReadableHandle( @Nonnull BufferedReader reader, @Nonnull Closeable closable )
+    {
+        super( closable );
+        this.m_reader = reader;
+    }
+
+    public EncodedReadableHandle( @Nonnull BufferedReader reader )
+    {
+        this( reader, reader );
+    }
+
+    @Nonnull
+    @Override
+    public String[] getMethodNames()
+    {
+        return new String[] {
+            "readLine",
+            "readAll",
+            "close",
+            "read",
+        };
+    }
+
+    @Override
+    public Object[] callMethod( @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
+    {
+        switch( method )
+        {
+            case 0:
+            {
+                // readLine
+                checkOpen();
+                boolean withTrailing = optBoolean( args, 0, false );
+                try
+                {
+                    String line = m_reader.readLine();
+                    if( line != null )
+                    {
+                        // While this is technically inaccurate, it's better than nothing
+                        if( withTrailing ) line += "\n";
+                        return new Object[] { line };
+                    }
+                    else
+                    {
+                        return null;
+                    }
+                }
+                catch( IOException e )
+                {
+                    return null;
+                }
+            }
+            case 1:
+                // readAll
+                checkOpen();
+                try
+                {
+                    StringBuilder result = new StringBuilder( "" );
+                    String line = m_reader.readLine();
+                    while( line != null )
+                    {
+                        result.append( line );
+                        line = m_reader.readLine();
+                        if( line != null )
+                        {
+                            result.append( "\n" );
+                        }
+                    }
+                    return new Object[] { result.toString() };
+                }
+                catch( IOException e )
+                {
+                    return null;
+                }
+            case 2:
+                // close
+                close();
+                return null;
+            case 3:
+                checkOpen();
+                try
+                {
+                    int count = optInt( args, 0, 1 );
+                    if( count < 0 )
+                    {
+                        // Whilst this may seem absurd to allow reading 0 characters, PUC Lua it so 
+                        // it seems best to remain somewhat consistent.
+                        throw new LuaException( "Cannot read a negative number of characters" );
+                    }
+                    else if( count <= BUFFER_SIZE )
+                    {
+                        // If we've got a small count, then allocate that and read it.
+                        char[] chars = new char[ count ];
+                        int read = m_reader.read( chars );
+
+                        return read < 0 ? null : new Object[] { new String( chars, 0, read ) };
+                    }
+                    else
+                    {
+                        // If we've got a large count, read in bunches of 8192.
+                        char[] buffer = new char[ BUFFER_SIZE ];
+
+                        // Read the initial set of characters, failing if none are read.
+                        int read = m_reader.read( buffer, 0, Math.min( buffer.length, count ) );
+                        if( read == -1 ) return null;
+
+                        StringBuilder out = new StringBuilder( read );
+                        count -= read;
+                        out.append( buffer, 0, read );
+
+                        // Otherwise read until we either reach the limit or we no longer consume
+                        // the full buffer.
+                        while( read >= BUFFER_SIZE && count > 0 )
+                        {
+                            read = m_reader.read( buffer, 0, Math.min( BUFFER_SIZE, count ) );
+                            if( read == -1 ) break;
+                            count -= read;
+                            out.append( buffer, 0, read );
+                        }
+
+                        return new Object[] { out.toString() };
+                    }
+                }
+                catch( IOException e )
+                {
+                    return null;
+                }
+            default:
+                return null;
+        }
+    }
+
+    public static BufferedReader openUtf8( ReadableByteChannel channel )
+    {
+        return open( channel, StandardCharsets.UTF_8 );
+    }
+
+    public static BufferedReader open( ReadableByteChannel channel, Charset charset )
+    {
+        return new BufferedReader( Channels.newReader( channel, charset.newDecoder(), -1 ) );
+    }
+}

src/main/java/dan200/computercraft/core/apis/handles/EncodedWritableHandle.java

@@ -4,41 +4,27 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 
 import javax.annotation.Nonnull;
-import java.io.*;
+import java.io.BufferedWriter;
+import java.io.Closeable;
+import java.io.IOException;
+import java.nio.channels.Channels;
+import java.nio.channels.WritableByteChannel;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 
-public class EncodedOutputHandle extends HandleGeneric
+public class EncodedWritableHandle extends HandleGeneric
 {
-    private final BufferedWriter m_writer;
+    private BufferedWriter m_writer;
 
-    public EncodedOutputHandle( BufferedWriter writer )
+    public EncodedWritableHandle( @Nonnull BufferedWriter writer, @Nonnull Closeable closable )
     {
-        super( writer );
+        super( closable );
         this.m_writer = writer;
     }
 
-    public EncodedOutputHandle( OutputStream stream )
+    public EncodedWritableHandle( @Nonnull BufferedWriter writer )
     {
-        this( stream, "UTF-8" );
-    }
-
-    public EncodedOutputHandle( OutputStream stream, String encoding )
-    {
-        this( makeWriter( stream, encoding ) );
-    }
-
-    private static BufferedWriter makeWriter( OutputStream stream, String encoding )
-    {
-        if( encoding == null ) encoding = "UTF-8";
-        OutputStreamWriter streamWriter;
-        try
-        {
-            streamWriter = new OutputStreamWriter( stream, encoding );
-        }
-        catch( UnsupportedEncodingException e )
-        {
-            streamWriter = new OutputStreamWriter( stream );
-        }
-        return new BufferedWriter( streamWriter );
+        this( writer, writer );
     }
 
     @Nonnull
@@ -125,4 +111,15 @@ public class EncodedOutputHandle extends HandleGeneric
                 return null;
         }
     }
+
+
+    public static BufferedWriter openUtf8( WritableByteChannel channel )
+    {
+        return open( channel, StandardCharsets.UTF_8 );
+    }
+
+    public static BufferedWriter open( WritableByteChannel channel, Charset charset )
+    {
+        return new BufferedWriter( Channels.newWriter( channel, charset.newEncoder(), -1 ) );
+    }
 }

src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java

@@ -3,17 +3,22 @@ package dan200.computercraft.core.apis.handles;
 import dan200.computercraft.api.lua.ILuaObject;
 import dan200.computercraft.api.lua.LuaException;
 
+import javax.annotation.Nonnull;
 import java.io.Closeable;
 import java.io.IOException;
+import java.nio.channels.SeekableByteChannel;
+
+import static dan200.computercraft.core.apis.ArgumentHelper.optInt;
+import static dan200.computercraft.core.apis.ArgumentHelper.optString;
 
 public abstract class HandleGeneric implements ILuaObject
 {
-    protected final Closeable m_closable;
-    protected boolean m_open = true;
+    private Closeable m_closable;
+    private boolean m_open = true;
 
-    public HandleGeneric( Closeable m_closable )
+    protected HandleGeneric( @Nonnull Closeable closable )
     {
-        this.m_closable = m_closable;
+        this.m_closable = closable;
     }
 
     protected void checkOpen() throws LuaException
@@ -21,7 +26,7 @@ public abstract class HandleGeneric implements ILuaObject
         if( !m_open ) throw new LuaException( "attempt to use a closed file" );
     }
 
-    protected void close()
+    protected final void close()
     {
         try
         {
@@ -31,5 +36,48 @@ public abstract class HandleGeneric implements ILuaObject
         catch( IOException ignored )
         {
         }
+        m_closable = null;
+    }
+
+    /**
+     * Shared implementation for various file handle types
+     *
+     * @param channel The channel to seek in
+     * @param args    The Lua arguments to process, like Lua's {@code file:seek}.
+     * @return The new position of the file, or null if some error occured.
+     * @throws LuaException If the arguments were invalid
+     * @see <a href="https://www.lua.org/manual/5.1/manual.html#pdf-file:seek">{@code file:seek} in the Lua manual.</a>
+     */
+    protected static Object[] handleSeek( SeekableByteChannel channel, Object[] args ) throws LuaException
+    {
+        try
+        {
+            String whence = optString( args, 0, "cur" );
+            long offset = optInt( args, 1, 0 );
+            switch( whence )
+            {
+                case "set":
+                    channel.position( offset );
+                    break;
+                case "cur":
+                    channel.position( channel.position() + offset );
+                    break;
+                case "end":
+                    channel.position( channel.size() + offset );
+                    break;
+                default:
+                    throw new LuaException( "bad argument #1 to 'seek' (invalid option '" + whence + "'" );
+            }
+
+            return new Object[] { channel.position() };
+        }
+        catch( IllegalArgumentException e )
+        {
+            return new Object[] { false, "Position is negative" };
+        }
+        catch( IOException e )
+        {
+            return null;
+        }
     }
 }

src/main/java/dan200/computercraft/core/apis/http/HTTPRequest.java

@@ -13,12 +13,17 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.ILuaObject;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.core.apis.IAPIEnvironment;
-import dan200.computercraft.core.apis.handles.BinaryInputHandle;
-import dan200.computercraft.core.apis.handles.EncodedInputHandle;
+import dan200.computercraft.core.apis.handles.ArrayByteChannel;
+import dan200.computercraft.core.apis.handles.BinaryReadableHandle;
+import dan200.computercraft.core.apis.handles.EncodedReadableHandle;
+import dan200.computercraft.core.tracking.TrackingField;
 
 import javax.annotation.Nonnull;
 import java.io.*;
 import java.net.*;
+import java.nio.channels.SeekableByteChannel;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -78,8 +83,10 @@ public class HTTPRequest implements Runnable
     private final String m_postText;
     private final Map<String, String> m_headers;
     private boolean m_binary;
+    private final String m_method;
+    private final boolean m_followRedirects;
 
-    public HTTPRequest( IAPIEnvironment environment, String urlString, URL url, final String postText, final Map<String, String> headers, boolean binary ) throws HTTPRequestException
+    public HTTPRequest( IAPIEnvironment environment, String urlString, URL url, final String postText, final Map<String, String> headers, boolean binary, final String method, final boolean followRedirects ) throws HTTPRequestException
     {
         m_environment = environment;
         m_urlString = urlString;
@@ -87,6 +94,8 @@ public class HTTPRequest implements Runnable
         m_binary = binary;
         m_postText = postText;
         m_headers = headers;
+        m_method = method;
+        m_followRedirects = followRedirects;
     }
 
     @Override
@@ -101,7 +110,7 @@ public class HTTPRequest implements Runnable
         {
             // Queue the failure event if not.
             String error = e.getMessage();
-            m_environment.queueEvent( "http_failure", new Object[] { m_urlString, error == null ? "Could not connect" : error, null } );
+            m_environment.queueEvent( "http_failure", new Object[]{ m_urlString, error == null ? "Could not connect" : error, null } );
             return;
         }
 
@@ -119,6 +128,8 @@ public class HTTPRequest implements Runnable
             {
                 connection.setRequestMethod( "GET" );
             }
+            if( m_method != null ) connection.setRequestMethod( m_method );
+            connection.setInstanceFollowRedirects( m_followRedirects );
 
             // Set headers
             connection.setRequestProperty( "accept-charset", "UTF-8" );
@@ -134,6 +145,11 @@ public class HTTPRequest implements Runnable
                 }
             }
 
+            // Add request size and count to the tracker before opening the connection
+            m_environment.addTrackingChange( TrackingField.HTTP_REQUESTS );
+            m_environment.addTrackingChange( TrackingField.HTTP_UPLOAD,
+                getHeaderSize( connection.getRequestProperties() ) + (m_postText == null ? 0 : m_postText.length()) );
+
             // Send POST text
             if( m_postText != null )
             {
@@ -170,6 +186,10 @@ public class HTTPRequest implements Runnable
             byte[] result = ByteStreams.toByteArray( is );
             is.close();
 
+            String encoding = connection.getContentEncoding();
+            Charset charset = encoding != null && Charset.isSupported( encoding )
+                ? Charset.forName( encoding ) : StandardCharsets.UTF_8;
+
             // We've got some sort of response, so let's build a resulting object.
             Joiner joiner = Joiner.on( ',' );
             Map<String, String> headers = new HashMap<>();
@@ -178,9 +198,14 @@ public class HTTPRequest implements Runnable
                 headers.put( header.getKey(), joiner.join( header.getValue() ) );
             }
 
-            InputStream contents = new ByteArrayInputStream( result );
+            m_environment.addTrackingChange( TrackingField.HTTP_DOWNLOAD,
+                getHeaderSize( connection.getHeaderFields() ) + result.length );
+
+            SeekableByteChannel contents = new ArrayByteChannel( result );
             ILuaObject stream = wrapStream(
-                m_binary ? new BinaryInputHandle( contents ) : new EncodedInputHandle( contents, connection.getContentEncoding() ),
+                m_binary
+                    ? new BinaryReadableHandle( contents )
+                    : new EncodedReadableHandle( EncodedReadableHandle.open( contents, charset ) ),
                 connection.getResponseCode(), headers
             );
 
@@ -189,17 +214,17 @@ public class HTTPRequest implements Runnable
             // Queue the appropriate event.
             if( responseSuccess )
             {
-                m_environment.queueEvent( "http_success", new Object[] { m_urlString, stream } );
+                m_environment.queueEvent( "http_success", new Object[]{ m_urlString, stream } );
             }
             else
             {
-                m_environment.queueEvent( "http_failure", new Object[] { m_urlString, "Could not connect", stream } );
+                m_environment.queueEvent( "http_failure", new Object[]{ m_urlString, "Could not connect", stream } );
             }
         }
         catch( IOException e )
         {
             // There was an error
-            m_environment.queueEvent( "http_failure", new Object[] { m_urlString, "Could not connect", null } );
+            m_environment.queueEvent( "http_failure", new Object[]{ m_urlString, "Could not connect", null } );
         }
     }
 
@@ -209,8 +234,8 @@ public class HTTPRequest implements Runnable
         final int methodOffset = oldMethods.length;
 
         final String[] newMethods = Arrays.copyOf( oldMethods, oldMethods.length + 2 );
-        newMethods[ methodOffset + 0 ] = "getResponseCode";
-        newMethods[ methodOffset + 1 ] = "getResponseHeaders";
+        newMethods[methodOffset + 0] = "getResponseCode";
+        newMethods[methodOffset + 1] = "getResponseHeaders";
 
         return new ILuaObject()
         {
@@ -233,12 +258,12 @@ public class HTTPRequest implements Runnable
                     case 0:
                     {
                         // getResponseCode
-                        return new Object[] { responseCode };
+                        return new Object[]{ responseCode };
                     }
                     case 1:
                     {
                         // getResponseHeaders
-                        return new Object[] { responseHeaders };
+                        return new Object[]{ responseHeaders };
                     }
                     default:
                     {
@@ -248,4 +273,15 @@ public class HTTPRequest implements Runnable
             }
         };
     }
+
+    private static long getHeaderSize( Map<String, List<String>> headers )
+    {
+        long size = 0;
+        for( Map.Entry<String, List<String>> header : headers.entrySet() )
+        {
+            size += header.getKey() == null ? 0 : header.getKey().length();
+            for( String value : header.getValue() ) size += value == null ? 0 : value.length() + 1;
+        }
+        return size;
+    }
 }

src/main/java/dan200/computercraft/core/apis/http/WebsocketConnection.java

@@ -12,7 +12,10 @@ import dan200.computercraft.api.lua.ILuaObject;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.core.apis.HTTPAPI;
 import dan200.computercraft.core.apis.IAPIEnvironment;
+import dan200.computercraft.core.tracking.TrackingField;
+import dan200.computercraft.shared.util.StringUtil;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.SimpleChannelInboundHandler;
@@ -25,6 +28,8 @@ import javax.annotation.Nullable;
 import java.io.Closeable;
 import java.io.IOException;
 
+import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
+
 public class WebsocketConnection extends SimpleChannelInboundHandler<Object> implements ILuaObject, Closeable
 {
     public static final String SUCCESS_EVENT = "websocket_success";
@@ -71,7 +76,7 @@ public class WebsocketConnection extends SimpleChannelInboundHandler<Object> imp
     private void onClosed()
     {
         close( true );
-        computer.queueEvent( CLOSE_EVENT, new Object[] { url } );
+        computer.queueEvent( CLOSE_EVENT, new Object[]{ url } );
     }
 
     @Override
@@ -102,7 +107,7 @@ public class WebsocketConnection extends SimpleChannelInboundHandler<Object> imp
         if( !handshaker.isHandshakeComplete() )
         {
             handshaker.finishHandshake( ch, (FullHttpResponse) msg );
-            computer.queueEvent( SUCCESS_EVENT, new Object[] { url, this } );
+            computer.queueEvent( SUCCESS_EVENT, new Object[]{ url, this } );
             return;
         }
 
@@ -115,14 +120,19 @@ public class WebsocketConnection extends SimpleChannelInboundHandler<Object> imp
         WebSocketFrame frame = (WebSocketFrame) msg;
         if( frame instanceof TextWebSocketFrame )
         {
-            computer.queueEvent( MESSAGE_EVENT, new Object[] { url, ((TextWebSocketFrame) frame).text() } );
+            String data = ((TextWebSocketFrame) frame).text();
+
+            computer.addTrackingChange( TrackingField.WEBSOCKET_INCOMING, data.length() );
+            computer.queueEvent( MESSAGE_EVENT, new Object[]{ url, data } );
         }
         else if( frame instanceof BinaryWebSocketFrame )
         {
             ByteBuf data = frame.content();
-            byte[] converted = new byte[ data.readableBytes() ];
+            byte[] converted = new byte[data.readableBytes()];
             data.readBytes( converted );
-            computer.queueEvent( MESSAGE_EVENT, new Object[] { url, data } );
+
+            computer.addTrackingChange( TrackingField.WEBSOCKET_INCOMING, converted.length );
+            computer.queueEvent( MESSAGE_EVENT, new Object[]{ url, converted } );
         }
         else if( frame instanceof CloseWebSocketFrame )
         {
@@ -135,7 +145,7 @@ public class WebsocketConnection extends SimpleChannelInboundHandler<Object> imp
     public void exceptionCaught( ChannelHandlerContext ctx, Throwable cause )
     {
         ctx.close();
-        computer.queueEvent( FAILURE_EVENT, new Object[] {
+        computer.queueEvent( FAILURE_EVENT, new Object[]{
             url,
             cause instanceof WebSocketHandshakeException ? cause.getMessage() : "Could not connect"
         } );
@@ -145,7 +155,7 @@ public class WebsocketConnection extends SimpleChannelInboundHandler<Object> imp
     @Override
     public String[] getMethodNames()
     {
-        return new String[] { "receive", "send", "close" };
+        return new String[]{ "receive", "send", "close" };
     }
 
     @Nullable
@@ -159,16 +169,20 @@ public class WebsocketConnection extends SimpleChannelInboundHandler<Object> imp
                 {
                     checkOpen();
                     Object[] event = context.pullEvent( MESSAGE_EVENT );
-                    if( event.length >= 3 && Objects.equal( event[ 1 ], url ) )
+                    if( event.length >= 3 && Objects.equal( event[1], url ) )
                     {
-                        return new Object[] { event[ 2 ] };
+                        return new Object[]{ event[2] };
                     }
                 }
             case 1:
             {
                 checkOpen();
-                String text = arguments.length > 0 && arguments[ 0 ] != null ? arguments[ 0 ].toString() : "";
-                channel.writeAndFlush( new TextWebSocketFrame( text ) );
+                String text = arguments.length > 0 && arguments[0] != null ? arguments[0].toString() : "";
+                boolean binary = optBoolean(arguments, 1, false);
+                computer.addTrackingChange( TrackingField.WEBSOCKET_OUTGOING, text.length() );
+                channel.writeAndFlush( binary
+                    ? new BinaryWebSocketFrame( Unpooled.wrappedBuffer( StringUtil.encodeString( text ) ) )
+                    : new TextWebSocketFrame( text ) );
                 return null;
             }
             case 2:

src/main/java/dan200/computercraft/core/apis/http/WebsocketConnector.java

@@ -21,6 +21,7 @@ import io.netty.handler.codec.http.HttpObjectAggregator;
 import io.netty.handler.codec.http.websocketx.WebSocketClientHandshaker;
 import io.netty.handler.codec.http.websocketx.WebSocketClientHandshakerFactory;
 import io.netty.handler.codec.http.websocketx.WebSocketVersion;
+import io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketClientCompressionHandler;
 import io.netty.handler.ssl.SslContext;
 import io.netty.handler.ssl.SslContextBuilder;
 
@@ -34,7 +35,7 @@ import java.security.KeyStore;
 import java.util.Map;
 import java.util.concurrent.Future;
 
-/*
+/**
  * Provides functionality to verify and connect to a remote websocket.
  */
 public final class WebsocketConnector
@@ -177,7 +178,7 @@ public final class WebsocketConnector
                 httpHeaders.add( header.getKey(), header.getValue() );
             }
 
-            WebSocketClientHandshaker handshaker = WebSocketClientHandshakerFactory.newHandshaker( uri, WebSocketVersion.V13, null, false, httpHeaders );
+            WebSocketClientHandshaker handshaker = WebSocketClientHandshakerFactory.newHandshaker( uri, WebSocketVersion.V13, null, true, httpHeaders );
             final WebsocketConnection connection = new WebsocketConnection( environment, api, handshaker, address );
 
             new Bootstrap()
@@ -190,7 +191,12 @@ public final class WebsocketConnector
                     {
                         ChannelPipeline p = ch.pipeline();
                         if( ssl != null ) p.addLast( ssl.newHandler( ch.alloc(), uri.getHost(), port ) );
-                        p.addLast( new HttpClientCodec(), new HttpObjectAggregator( 8192 ), connection );
+                        p.addLast(
+                            new HttpClientCodec(),
+                            new HttpObjectAggregator( 8192 ),
+                            WebSocketClientCompressionHandler.INSTANCE,
+                            connection
+                        );
                     }
                 } )
                 .remoteAddress( socketAddress )

src/main/java/dan200/computercraft/core/computer/Computer.java

@@ -12,6 +12,7 @@ import dan200.computercraft.api.filesystem.IFileSystem;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
 import dan200.computercraft.api.lua.*;
+import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.apis.*;
 import dan200.computercraft.core.filesystem.FileSystem;
@@ -19,6 +20,8 @@ import dan200.computercraft.core.filesystem.FileSystemException;
 import dan200.computercraft.core.lua.CobaltLuaMachine;
 import dan200.computercraft.core.lua.ILuaMachine;
 import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.core.tracking.Tracking;
+import dan200.computercraft.core.tracking.TrackingField;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -166,6 +169,12 @@ public class Computer
             m_computer.setLabel( label );
         }
 
+        @Override
+        public void addTrackingChange( TrackingField field, long change )
+        {
+            Tracking.addValue( m_computer, field, change );
+        }
+
         public void onPeripheralChanged( int side, IPeripheral peripheral )
         {
             synchronized( m_computer.m_peripherals )
@@ -665,6 +674,11 @@ public class Computer
     {
         m_apis.add( api );
     }
+
+    public void addAPI( dan200.computercraft.core.apis.ILuaAPI api )
+    {
+        addAPI( (ILuaAPI) api );
+    }
     
     public void setPeripheral( int side, IPeripheral peripheral )
     {

src/main/java/dan200/computercraft/core/computer/ComputerThread.java

@@ -7,6 +7,7 @@
 package dan200.computercraft.core.computer;
 
 import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.core.tracking.Tracking;
 
 import java.util.HashSet;
 import java.util.Set;
@@ -68,17 +69,17 @@ public class ComputerThread
             s_stopped = false;
             if( s_threads == null || s_threads.length != ComputerCraft.computer_threads )
             {
-                s_threads = new Thread[ ComputerCraft.computer_threads ];
+                s_threads = new Thread[ComputerCraft.computer_threads];
             }
 
             SecurityManager manager = System.getSecurityManager();
             final ThreadGroup group = manager == null ? Thread.currentThread().getThreadGroup() : manager.getThreadGroup();
             for( int i = 0; i < s_threads.length; i++ )
             {
-                Thread thread = s_threads[ i ];
+                Thread thread = s_threads[i];
                 if( thread == null || !thread.isAlive() )
                 {
-                    thread = s_threads[ i ] = new Thread( group, new TaskExecutor(), "ComputerCraft-Computer-Manager-" + s_ManagerCounter.getAndIncrement() );
+                    thread = s_threads[i] = new Thread( group, new TaskExecutor(), "ComputerCraft-Computer-Manager-" + s_ManagerCounter.getAndIncrement() );
                     thread.setDaemon( true );
                     thread.start();
                 }
@@ -195,6 +196,8 @@ public class ComputerThread
                 thread.start();
             }
 
+            long start = System.nanoTime();
+
             // Execute the task
             runner.submit( task );
 
@@ -221,6 +224,23 @@ public class ComputerThread
                     // Interrupt the thread
                     if( !done )
                     {
+                        StringBuilder builder = new StringBuilder( "Terminating " );
+                        if( computer != null )
+                        {
+                            builder.append( "computer " ).append( computer.getID() );
+                        }
+                        else
+                        {
+                            builder.append( "unknown computer" );
+                        }
+
+                        builder.append( ". Thread is currently running" );
+                        for( StackTraceElement element : thread.getStackTrace() )
+                        {
+                            builder.append( "\n  at " ).append( element );
+                        }
+                        ComputerCraft.log.error( builder.toString() );
+
                         thread.interrupt();
                         thread = null;
                         runner = null;
@@ -229,6 +249,10 @@ public class ComputerThread
             }
             finally
             {
+                long stop = System.nanoTime();
+                Computer computer = task.getOwner();
+                if( computer != null ) Tracking.addTaskTiming( computer, stop - start );
+
                 // Re-add it back onto the queue or remove it
                 synchronized( s_taskLock )
                 {

src/main/java/dan200/computercraft/core/computer/IComputerOwned.java

@@ -0,0 +1,9 @@
+package dan200.computercraft.core.computer;
+
+import javax.annotation.Nullable;
+
+public interface IComputerOwned
+{
+    @Nullable
+    Computer getComputer();
+}

src/main/java/dan200/computercraft/core/computer/MainThread.java

@@ -6,14 +6,17 @@
 
 package dan200.computercraft.core.computer;
 
-import java.util.LinkedList;
+import dan200.computercraft.core.tracking.Tracking;
+
+import java.util.ArrayDeque;
+import java.util.Queue;
 
 public class MainThread
 {
     private static final int MAX_TASKS_PER_TICK = 1000;
     private static final int MAX_TASKS_TOTAL = 50000;
 
-    private static final LinkedList<ITask> m_outstandingTasks = new LinkedList<>();
+    private static final Queue<ITask> m_outstandingTasks = new ArrayDeque<>();
     private static final Object m_nextUnusedTaskIDLock = new Object();
     private static long m_nextUnusedTaskID = 0;
 
@@ -31,7 +34,7 @@ public class MainThread
         {
             if( m_outstandingTasks.size() < MAX_TASKS_TOTAL )
             {
-                m_outstandingTasks.addLast( task );
+                m_outstandingTasks.offer( task );
                 return true;
             }
         }
@@ -46,14 +49,17 @@ public class MainThread
             ITask task = null;
             synchronized( m_outstandingTasks )
             {
-                if( m_outstandingTasks.size() > 0 )
-                {
-                    task = m_outstandingTasks.removeFirst();
-                }
+                task = m_outstandingTasks.poll();
             }
             if( task != null )
             {
+                long start = System.nanoTime();
                 task.execute();
+
+                long stop = System.nanoTime();
+                Computer computer = task.getOwner();
+                if( computer != null ) Tracking.addServerTiming( computer, stop - start );
+
                 ++tasksThisTick;
             }
             else

src/main/java/dan200/computercraft/core/filesystem/ComboMount.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.filesystem.IMount;
 import javax.annotation.Nonnull;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.channels.ReadableByteChannel;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
@@ -114,6 +115,7 @@ public class ComboMount implements IMount
 
     @Nonnull
     @Override
+    @Deprecated
     public InputStream openForRead( @Nonnull String path ) throws IOException
     {
         for( int i=m_parts.length-1; i>=0; --i )
@@ -126,4 +128,19 @@ public class ComboMount implements IMount
         }
         throw new IOException( "/" + path + ": No such file" );
     }
+
+    @Nonnull
+    @Override
+    public ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
+    {
+        for( int i=m_parts.length-1; i>=0; --i )
+        {
+            IMount part = m_parts[i];
+            if( part.exists( path ) && !part.isDirectory( path ) )
+            {
+                return part.openChannelForRead( path );
+            }
+        }
+        throw new IOException( "/" + path + ": No such file" );
+    }
 }

src/main/java/dan200/computercraft/core/filesystem/EmptyMount.java

@@ -9,34 +9,36 @@ package dan200.computercraft.core.filesystem;
 import dan200.computercraft.api.filesystem.IMount;
 
 import javax.annotation.Nonnull;
+import java.io.IOException;
 import java.io.InputStream;
+import java.nio.channels.ReadableByteChannel;
 import java.util.List;
 
 public class EmptyMount implements IMount
-{    
+{
     public EmptyMount()
     {
     }
-    
+
     // IMount implementation
-    
+
     @Override
     public boolean exists( @Nonnull String path )
     {
         return path.isEmpty();
     }
-    
+
     @Override
     public boolean isDirectory( @Nonnull String path )
     {
         return path.isEmpty();
     }
-    
+
     @Override
     public void list( @Nonnull String path, @Nonnull List<String> contents )
     {
     }
-    
+
     @Override
     public long getSize( @Nonnull String path )
     {
@@ -45,8 +47,17 @@ public class EmptyMount implements IMount
 
     @Nonnull
     @Override
-    public InputStream openForRead( @Nonnull String path )
+    @Deprecated
+    public InputStream openForRead( @Nonnull String path ) throws IOException
     {
-        return null;
+        throw new IOException( "/" + path + ": No such file" );
+    }
+
+    @Nonnull
+    @Override
+    @Deprecated
+    public ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
+    {
+        throw new IOException( "/" + path + ": No such file" );
     }
 }

src/main/java/dan200/computercraft/core/filesystem/FileMount.java

@@ -10,64 +10,43 @@ import dan200.computercraft.api.filesystem.IWritableMount;
 
 import javax.annotation.Nonnull;
 import java.io.*;
+import java.nio.ByteBuffer;
+import java.nio.channels.*;
+import java.nio.file.Files;
+import java.nio.file.StandardOpenOption;
 import java.util.List;
 
 public class FileMount implements IWritableMount
 {
-    private static int MINIMUM_FILE_SIZE = 500;
-    
-    private class CountingOutputStream extends OutputStream
+    private static final int MINIMUM_FILE_SIZE = 500;
+
+    private class WritableCountingChannel implements WritableByteChannel
     {
-        private OutputStream m_innerStream;
-        private long m_ignoredBytesLeft;
-        
-        public CountingOutputStream( OutputStream innerStream, long bytesToIgnore )
+
+        private final WritableByteChannel m_inner;
+        long m_ignoredBytesLeft;
+
+        WritableCountingChannel( WritableByteChannel inner, long bytesToIgnore )
         {
-            m_innerStream = innerStream;
+            m_inner = inner;
             m_ignoredBytesLeft = bytesToIgnore;
         }
-        
-        @Override
-        public void close() throws IOException
-        {
-            m_innerStream.close();
-        }
-        
-        @Override
-        public void flush() throws IOException
-        {
-            m_innerStream.flush();
-        }
-        
-        @Override
-        public void write( @Nonnull byte[] b ) throws IOException
-        {
-            count( b.length );
-            m_innerStream.write( b );
-        }
-        
-        @Override
-        public void write( @Nonnull byte[] b, int off, int len ) throws IOException
-        {
-            count( len );
-            m_innerStream.write( b, off, len );
-        }
 
         @Override
-        public void write( int b ) throws IOException
+        public int write( @Nonnull ByteBuffer b ) throws IOException
         {
-            count( 1 );
-            m_innerStream.write( b );
+            count( b.remaining() );
+            return m_inner.write( b );
         }
 
-        private void count( long n ) throws IOException
+        void count( long n ) throws IOException
         {
             m_ignoredBytesLeft -= n;
             if( m_ignoredBytesLeft < 0 )
             {
                 long newBytes = -m_ignoredBytesLeft;
                 m_ignoredBytesLeft = 0;
-                
+
                 long bytesLeft = m_capacity - m_usedSpace;
                 if( newBytes > bytesLeft )
                 {
@@ -79,12 +58,79 @@ public class FileMount implements IWritableMount
                 }
             }
         }
+
+        @Override
+        public boolean isOpen()
+        {
+            return m_inner.isOpen();
+        }
+
+        @Override
+        public void close() throws IOException
+        {
+            m_inner.close();
+        }
     }
-    
+
+    private class SeekableCountingChannel extends WritableCountingChannel implements SeekableByteChannel
+    {
+        private final SeekableByteChannel m_inner;
+
+        SeekableCountingChannel( SeekableByteChannel inner, long bytesToIgnore )
+        {
+            super( inner, bytesToIgnore );
+            this.m_inner = inner;
+        }
+
+        @Override
+        public SeekableByteChannel position( long newPosition ) throws IOException
+        {
+            if( !isOpen() ) throw new ClosedChannelException();
+            if( newPosition < 0 ) throw new IllegalArgumentException();
+
+            long delta = newPosition - m_inner.position();
+            if( delta < 0 )
+            {
+                m_ignoredBytesLeft -= delta;
+            }
+            else
+            {
+                count( delta );
+            }
+
+            return m_inner.position( newPosition );
+        }
+
+        @Override
+        public SeekableByteChannel truncate( long size ) throws IOException
+        {
+            throw new IOException( "Not yet implemented" );
+        }
+
+        @Override
+        public int read( ByteBuffer dst ) throws IOException
+        {
+            if( !m_inner.isOpen() ) throw new ClosedChannelException();
+            throw new NonReadableChannelException();
+        }
+
+        @Override
+        public long position() throws IOException
+        {
+            return m_inner.position();
+        }
+
+        @Override
+        public long size() throws IOException
+        {
+            return m_inner.size();
+        }
+    }
+
     private File m_rootPath;
     private long m_capacity;
     private long m_usedSpace;
-    
+
     public FileMount( File rootPath, long capacity )
     {
         m_rootPath = rootPath;
@@ -93,7 +139,7 @@ public class FileMount implements IWritableMount
     }
 
     // IMount implementation
-    
+
     @Override
     public boolean exists( @Nonnull String path )
     {
@@ -107,7 +153,7 @@ public class FileMount implements IWritableMount
             return file.exists();
         }
     }
-    
+
     @Override
     public boolean isDirectory( @Nonnull String path )
     {
@@ -121,7 +167,7 @@ public class FileMount implements IWritableMount
             return file.exists() && file.isDirectory();
         }
     }
-    
+
     @Override
     public void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException
     {
@@ -150,7 +196,7 @@ public class FileMount implements IWritableMount
             {
                 throw new IOException( "/" + path + ": Not a directory" );
             }
-        }    
+        }
     }
 
     @Override
@@ -180,9 +226,10 @@ public class FileMount implements IWritableMount
         }
         throw new IOException( "/" + path + ": No such file" );
     }
-    
+
     @Nonnull
     @Override
+    @Deprecated
     public InputStream openForRead( @Nonnull String path ) throws IOException
     {
         if( created() )
@@ -193,11 +240,26 @@ public class FileMount implements IWritableMount
                 return new FileInputStream( file );
             }
         }
-        throw new IOException( "/" + path +  ": No such file" );
+        throw new IOException( "/" + path + ": No such file" );
     }
-    
+
+    @Nonnull
+    @Override
+    public ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
+    {
+        if( created() )
+        {
+            File file = getRealPath( path );
+            if( file.exists() && !file.isDirectory() )
+            {
+                return FileChannel.open( file.toPath(), StandardOpenOption.READ );
+            }
+        }
+        throw new IOException( "/" + path + ": No such file" );
+    }
+
     // IWritableMount implementation
-    
+
     @Override
     public void makeDirectory( @Nonnull String path ) throws IOException
     {
@@ -224,7 +286,7 @@ public class FileMount implements IWritableMount
             {
                 throw new IOException( "/" + path + ": Out of space" );
             }
-            
+
             boolean success = file.mkdirs();
             if( success )
             {
@@ -236,7 +298,7 @@ public class FileMount implements IWritableMount
             }
         }
     }
-    
+
     @Override
     public void delete( @Nonnull String path ) throws IOException
     {
@@ -244,7 +306,7 @@ public class FileMount implements IWritableMount
         {
             throw new IOException( "/" + path + ": Access denied" );
         }
-        
+
         if( created() )
         {
             File file = getRealPath( path );
@@ -254,7 +316,7 @@ public class FileMount implements IWritableMount
             }
         }
     }
-    
+
     private void deleteRecursively( File file ) throws IOException
     {
         // Empty directories first
@@ -266,7 +328,7 @@ public class FileMount implements IWritableMount
                 deleteRecursively( new File( file, aChildren ) );
             }
         }
-        
+
         // Then delete
         long fileSize = file.isDirectory() ? 0 : file.length();
         boolean success = file.delete();
@@ -279,10 +341,26 @@ public class FileMount implements IWritableMount
             throw new IOException( "Access denied" );
         }
     }
-    
+
     @Nonnull
     @Override
+    @Deprecated
     public OutputStream openForWrite( @Nonnull String path ) throws IOException
+    {
+        return Channels.newOutputStream( openChannelForWrite( path ) );
+    }
+
+    @Nonnull
+    @Override
+    @Deprecated
+    public OutputStream openForAppend( @Nonnull String path ) throws IOException
+    {
+        return Channels.newOutputStream( openChannelForAppend( path ) );
+    }
+
+    @Nonnull
+    @Override
+    public WritableByteChannel openChannelForWrite( @Nonnull String path ) throws IOException
     {
         create();
         File file = getRealPath( path );
@@ -308,13 +386,14 @@ public class FileMount implements IWritableMount
                 m_usedSpace -= Math.max( file.length(), MINIMUM_FILE_SIZE );
                 m_usedSpace += MINIMUM_FILE_SIZE;
             }
-            return new CountingOutputStream( new FileOutputStream( file, false ), MINIMUM_FILE_SIZE );
+            return new SeekableCountingChannel( Files.newByteChannel( file.toPath(), StandardOpenOption.WRITE, StandardOpenOption.CREATE ),
+                MINIMUM_FILE_SIZE );
         }
     }
-    
+
     @Nonnull
     @Override
-    public OutputStream openForAppend( @Nonnull String path ) throws IOException
+    public WritableByteChannel openChannelForAppend( @Nonnull String path ) throws IOException
     {
         if( created() )
         {
@@ -329,7 +408,9 @@ public class FileMount implements IWritableMount
             }
             else
             {
-                return new CountingOutputStream( new FileOutputStream( file, true ), Math.max( MINIMUM_FILE_SIZE - file.length(), 0 ) );
+                // Allowing seeking when appending is not recommended, so we use a separate channel.
+                return new WritableCountingChannel( Files.newByteChannel( file.toPath(), StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.APPEND ),
+                    Math.max( MINIMUM_FILE_SIZE - file.length(), 0 ) );
             }
         }
         else
@@ -337,23 +418,23 @@ public class FileMount implements IWritableMount
             throw new IOException( "/" + path + ": No such file" );
         }
     }
-    
+
     @Override
     public long getRemainingSpace()
     {
         return Math.max( m_capacity - m_usedSpace, 0 );
     }
-    
+
     public File getRealPath( String path )
     {
         return new File( m_rootPath, path );
     }
-    
+
     private boolean created()
     {
         return m_rootPath.exists();
     }
-    
+
     private void create() throws IOException
     {
         if( !m_rootPath.exists() )
@@ -365,7 +446,7 @@ public class FileMount implements IWritableMount
             }
         }
     }
-    
+
     private long measureUsedSpace( File file )
     {
         if( !file.exists() )

src/main/java/dan200/computercraft/core/filesystem/FileSystem.java

@@ -6,13 +6,23 @@
 
 package dan200.computercraft.core.filesystem;
 
+import com.google.common.io.ByteStreams;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.filesystem.IFileSystem;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
 
-import java.io.*;
+import javax.annotation.Nonnull;
+import java.io.Closeable;
+import java.io.IOException;
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.channels.WritableByteChannel;
+import java.nio.file.AccessDeniedException;
 import java.util.*;
+import java.util.function.Function;
 import java.util.regex.Pattern;
 
 public class FileSystem
@@ -146,14 +156,14 @@ public class FileSystem
             }
         }
     
-        public InputStream openForRead( String path ) throws FileSystemException
+        public ReadableByteChannel openForRead( String path ) throws FileSystemException
         {
             path = toLocal( path );
             try
             {
                 if( m_mount.exists( path ) && !m_mount.isDirectory( path ) )
                 {
-                    return m_mount.openForRead( path );
+                    return m_mount.openChannelForRead( path );
                 }
                 else
                 {
@@ -209,13 +219,17 @@ public class FileSystem
                     m_writableMount.delete( path );
                 }
             }
+            catch( AccessDeniedException e )
+            {
+                throw new FileSystemException( "Access denied" );
+            }
             catch( IOException e )
             {
                 throw new FileSystemException( e.getMessage() );
             }
         }
     
-        public OutputStream openForWrite( String path ) throws FileSystemException
+        public WritableByteChannel openForWrite( String path ) throws FileSystemException
         {
             if( m_writableMount == null )
             {
@@ -238,16 +252,20 @@ public class FileSystem
                             m_writableMount.makeDirectory( dir );
                         }
                     }
-                    return m_writableMount.openForWrite( path );
+                    return m_writableMount.openChannelForWrite( path );
                 }
             }
+            catch( AccessDeniedException e )
+            {
+                throw new FileSystemException( "Access denied" );
+            }
             catch( IOException e )
             {
                 throw new FileSystemException( e.getMessage() );
             }
         }
         
-        public OutputStream openForAppend( String path ) throws FileSystemException
+        public WritableByteChannel openForAppend( String path ) throws FileSystemException
         {
             if( m_writableMount == null )
             {
@@ -266,7 +284,7 @@ public class FileSystem
                             m_writableMount.makeDirectory( dir );
                         }
                     }
-                    return m_writableMount.openForWrite( path );
+                    return m_writableMount.openChannelForWrite( path );
                 }
                 else if( m_mount.isDirectory( path ) )
                 {
@@ -274,9 +292,13 @@ public class FileSystem
                 }
                 else
                 {
-                    return m_writableMount.openForAppend( path );
+                    return m_writableMount.openChannelForAppend( path );
                 }
             }
+            catch( AccessDeniedException e )
+            {
+                throw new FileSystemException( "Access denied" );
+            }
             catch( IOException e )
             {
                 throw new FileSystemException( e.getMessage() );
@@ -291,10 +313,12 @@ public class FileSystem
         }
     }
 
-    private final FileSystemMount m_wrapper = new FileSystemMount( this );
+    private final FileSystemWrapperMount m_wrapper = new FileSystemWrapperMount( this );
     private final Map<String, MountWrapper> m_mounts = new HashMap<>();
-    private final Set<Closeable> m_openFiles = Collections.newSetFromMap( new WeakHashMap<Closeable, Boolean>() );
-    
+
+    private final HashMap<WeakReference<FileSystemWrapper<?>>, Closeable> m_openFiles = new HashMap<>();
+    private final ReferenceQueue<FileSystemWrapper<?>> m_openFileQueue = new ReferenceQueue<>();
+
     public FileSystem( String rootLabel, IMount rootMount ) throws FileSystemException
     {
         mount( rootLabel, "", rootMount );
@@ -310,24 +334,15 @@ public class FileSystem
         // Close all dangling open files
         synchronized( m_openFiles )
         {
-            for( Closeable file : m_openFiles )
-            {
-                try {
-                    file.close();
-                } catch (IOException e) {
-                    // Ignore
-                }
-            }
+            for( Closeable file : m_openFiles.values() ) closeQuietly( file );
             m_openFiles.clear();
+            while( m_openFileQueue.poll() != null ) ;
         }
     }
     
     public synchronized void mount( String label, String location, IMount mount ) throws FileSystemException
     {
-        if( mount == null )
-        {
-            throw new NullPointerException();
-        }
+        if( mount == null ) throw new NullPointerException();
         location = sanitizePath( location );
         if( location.contains( ".." ) ) {
             throw new FileSystemException( "Cannot mount below the root" );
@@ -348,24 +363,18 @@ public class FileSystem
         }                    
         mount( new MountWrapper( label, location, mount ) );
     }
-    
+
     private synchronized void mount( MountWrapper wrapper )
     {
         String location = wrapper.getLocation();
-        if( m_mounts.containsKey( location ) )
-        {
-            m_mounts.remove( location );
-        }
+        m_mounts.remove( location );
         m_mounts.put( location, wrapper );
     }
         
     public synchronized void unmount( String path )
     {
         path = sanitizePath( path );
-        if( m_mounts.containsKey( path ) )
-        {
-            m_mounts.remove( path );
-        }
+        m_mounts.remove( path );
     }
         
     public synchronized String combine( String path, String childPath )
@@ -599,108 +608,85 @@ public class FileSystem
         else
         {
             // Copy a file:
-            InputStream source = null;
-            OutputStream destination = null;
-            try
+            try( ReadableByteChannel source = sourceMount.openForRead( sourcePath );
+                 WritableByteChannel destination = destinationMount.openForWrite( destinationPath ) )
             {
-                // Open both files
-                source = sourceMount.openForRead( sourcePath );
-                destination = destinationMount.openForWrite( destinationPath );
-            
                 // Copy bytes as fast as we can
-                byte[] buffer = new byte[1024];
-                while( true )
-                {
-                    int bytesRead = source.read( buffer );
-                    if( bytesRead >= 0 )
-                    {
-                        destination.write( buffer, 0, bytesRead );
-                    }
-                    else
-                    {
-                        break;
-                    }
-                }
+                ByteStreams.copy( source, destination );
+            }
+            catch( AccessDeniedException e )
+            {
+                throw new FileSystemException( "Access denied" );
             }
             catch( IOException e )
             {
                 throw new FileSystemException( e.getMessage() );
             }
-            finally
+        }
+    }
+
+    private void cleanup()
+    {
+        synchronized( m_openFiles )
+        {
+            Reference<?> ref;
+            while( (ref = m_openFileQueue.poll()) != null )
             {
-                // Close both files
-                if( source != null )
-                {
-                    try {
-                        source.close();
-                    } catch( IOException e ) {
-                        // nobody cares
-                    }
-                }
-                if( destination != null )
-                {
-                    try {
-                        destination.close();
-                    } catch( IOException e ) {
-                        // nobody cares
-                    }
-                }
+                Closeable file = m_openFiles.remove( ref );
+                if( file != null ) closeQuietly( file );
             }
         }
     }
 
-    private synchronized <T> T openFile( T file, Closeable handle ) throws FileSystemException
+    private synchronized <T extends Closeable> FileSystemWrapper<T> openFile( @Nonnull T file ) throws FileSystemException
     {
         synchronized( m_openFiles )
         {
             if( ComputerCraft.maximumFilesOpen > 0 &&
                 m_openFiles.size() >= ComputerCraft.maximumFilesOpen )
             {
-                if( handle != null )
-                {
-                    try {
-                        handle.close();
-                    } catch ( IOException ignored ) {
-                        // shrug
-                    }
-                }
-                throw new FileSystemException("Too many files already open");
+                closeQuietly( file );
+                throw new FileSystemException( "Too many files already open" );
             }
 
-            m_openFiles.add( handle );
-            return file;
+            FileSystemWrapper<T> wrapper = new FileSystemWrapper<>( this, file, m_openFileQueue );
+            m_openFiles.put( wrapper.self, file );
+            return wrapper;
         }
     }
 
-    private synchronized void closeFile( Closeable handle ) throws IOException
+    synchronized void removeFile( FileSystemWrapper<?> handle ) 
     {
         synchronized( m_openFiles )
         {
-            m_openFiles.remove( handle );
-            handle.close();
+            m_openFiles.remove( handle.self );
         }
     }
-    
-    public synchronized InputStream openForRead( String path ) throws FileSystemException
+
+    public synchronized <T extends Closeable> FileSystemWrapper<T> openForRead( String path, Function<ReadableByteChannel, T> open ) throws FileSystemException
     {
-        path = sanitizePath ( path );
+        cleanup();
+
+        path = sanitizePath( path );
         MountWrapper mount = getMount( path );
-        InputStream stream = mount.openForRead( path );
-        if( stream != null )
+        ReadableByteChannel channel = mount.openForRead( path );
+        if( channel != null )
         {
-            return openFile( new ClosingInputStream( stream ), stream );
+            return openFile( open.apply( channel ) );
         }
         return null;
     }
 
-    public synchronized OutputStream openForWrite( String path, boolean append ) throws FileSystemException
+    public synchronized <T extends Closeable> FileSystemWrapper<T> openForWrite( String path, boolean append, Function<WritableByteChannel, T> open ) throws FileSystemException
     {
-        path = sanitizePath ( path );
+        cleanup();
+
+        path = sanitizePath( path );
         MountWrapper mount = getMount( path );
-        OutputStream stream = append ? mount.openForAppend( path ) : mount.openForWrite( path );
-        if( stream != null )
+        WritableByteChannel channel = append ? mount.openForAppend( path ) : mount.openForWrite( path );
+        if( channel != null )
         {
-            return openFile( new ClosingOutputStream( stream ), stream );
+            return openFile( open.apply( channel ) );
         }
         return null;
     }
@@ -865,33 +851,14 @@ public class FileSystem
         }
     }
 
-    private class ClosingInputStream extends FilterInputStream
+    private static void closeQuietly( Closeable c )
     {
-        protected ClosingInputStream( InputStream in )
+        try
         {
-            super( in );
+            c.close();
         }
-
-        @Override
-        public void close() throws IOException
+        catch( IOException ignored )
         {
-            super.close();
-            closeFile( in );
-        }
-    }
-
-    private class ClosingOutputStream extends FilterOutputStream
-    {
-        protected ClosingOutputStream( OutputStream out )
-        {
-            super( out );
-        }
-
-        @Override
-        public void close() throws IOException
-        {
-            super.close();
-            closeFile( out );
         }
     }
 }

src/main/java/dan200/computercraft/core/filesystem/FileSystemMount.java

@@ -1,185 +1,132 @@
 package dan200.computercraft.core.filesystem;
 
-import dan200.computercraft.api.filesystem.IFileSystem;
+import dan200.computercraft.api.filesystem.IMount;
 
 import javax.annotation.Nonnull;
 import java.io.IOException;
 import java.io.InputStream;
-import java.io.OutputStream;
-import java.util.Collections;
-import java.util.List;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.file.FileSystem;
+import java.nio.file.*;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.*;
+import java.util.stream.Stream;
 
-public class FileSystemMount implements IFileSystem
+public class FileSystemMount implements IMount
 {
-    private final FileSystem m_filesystem;
+    private final Entry rootEntry;
 
-    public FileSystemMount( FileSystem m_filesystem )
+    public FileSystemMount( FileSystem fileSystem, String root ) throws IOException
     {
-        this.m_filesystem = m_filesystem;
-    }
+        Path rootPath = fileSystem.getPath( root );
+        rootEntry = new Entry( "", rootPath );
 
-    @Override
-    public void makeDirectory( @Nonnull String path ) throws IOException
-    {
-        try
+        Queue<Entry> entries = new ArrayDeque<>();
+        entries.add( rootEntry );
+        while( !entries.isEmpty() )
         {
-            m_filesystem.makeDir( path );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
+            Entry entry = entries.remove();
+            try( Stream<Path> childStream = Files.list( entry.path ) )
+            {
+                Iterator<Path> children = childStream.iterator();
+                while( children.hasNext() )
+                {
+                    Path childPath = children.next();
+                    Entry child = new Entry( childPath.getFileName().toString(), childPath );
+                    entry.children.put( child.name, child );
+                    if( child.directory ) entries.add( child );
+                }
+            }
         }
     }
 
     @Override
-    public void delete( @Nonnull String path ) throws IOException
+    public boolean exists( @Nonnull String path )
     {
-        try
-        {
-            m_filesystem.delete( path );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
-    }
-
-    @Nonnull
-    @Override
-    public OutputStream openForWrite( @Nonnull String path ) throws IOException
-    {
-        try
-        {
-            return m_filesystem.openForWrite( path, false );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
-    }
-
-    @Nonnull
-    @Override
-    public OutputStream openForAppend( @Nonnull String path ) throws IOException
-    {
-        try
-        {
-            return m_filesystem.openForWrite( path, true );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
+        return getFile( path ) != null;
     }
 
     @Override
-    public long getRemainingSpace() throws IOException
+    public boolean isDirectory( @Nonnull String path )
     {
-        try
-        {
-            return m_filesystem.getFreeSpace( "/" );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
-    }
-
-    @Override
-    public boolean exists( @Nonnull String path ) throws IOException
-    {
-        try
-        {
-            return m_filesystem.exists( path );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
-    }
-
-    @Override
-    public boolean isDirectory( @Nonnull String path ) throws IOException
-    {
-        try
-        {
-            return m_filesystem.exists( path );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
+        Entry entry = getFile( path );
+        return entry != null && entry.directory;
     }
 
     @Override
     public void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException
     {
-        try
-        {
-            Collections.addAll( contents, m_filesystem.list( path ) );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
+        Entry entry = getFile( path );
+        if( entry == null || !entry.directory ) throw new IOException( "/" + path + ": Not a directory" );
+
+        contents.addAll( entry.children.keySet() );
     }
 
     @Override
     public long getSize( @Nonnull String path ) throws IOException
     {
-        try
-        {
-            return m_filesystem.getSize( path );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
+        Entry file = getFile( path );
+        if( file == null ) throw new IOException( "/" + path + ": No such file" );
+        return file.size;
     }
 
     @Nonnull
     @Override
+    @Deprecated
     public InputStream openForRead( @Nonnull String path ) throws IOException
     {
-        try
-        {
-            return m_filesystem.openForRead( path );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
-        }
+        Entry file = getFile( path );
+        if( file == null || file.directory ) throw new IOException( "/" + path + ": No such file" );
+
+        return Files.newInputStream( file.path, StandardOpenOption.READ );
     }
 
+    @Nonnull
     @Override
-    public String combine( String path, String child )
+    public ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
     {
-        return m_filesystem.combine( path, child );
+        Entry file = getFile( path );
+        if( file == null || file.directory ) throw new IOException( "/" + path + ": No such file" );
+
+        return Files.newByteChannel( file.path, StandardOpenOption.READ );
     }
 
-    @Override
-    public void copy( String from, String to ) throws IOException
+    private Entry getFile( String path )
     {
-        try
+        if( path.equals( "" ) ) return rootEntry;
+        if( !path.contains( "/" ) ) return rootEntry.children.get( path );
+
+        String[] components = path.split( "/" );
+        Entry entry = rootEntry;
+        for( String component : components )
         {
-            m_filesystem.copy( from, to );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
+            if( entry == null || entry.children == null ) return null;
+            entry = entry.children.get( component );
         }
+
+        return entry;
     }
 
-    @Override
-    public void move( String from, String to ) throws IOException
+    private static class Entry
     {
-        try
+        final String name;
+        final Path path;
+
+        final boolean directory;
+        final long size;
+        final Map<String, Entry> children;
+
+        private Entry( String name, Path path ) throws IOException
         {
-            m_filesystem.move( from, to );
-        }
-        catch( FileSystemException e )
-        {
-            throw new IOException( e.getMessage() );
+            if( name.endsWith( "/" ) || name.endsWith( "\\" ) ) name = name.substring( 0, name.length() - 1 );
+
+            this.name = name;
+            this.path = path;
+
+            BasicFileAttributes attributes = Files.readAttributes( path, BasicFileAttributes.class, LinkOption.NOFOLLOW_LINKS );
+            this.directory = attributes.isDirectory();
+            this.size = directory ? 0 : attributes.size();
+            this.children = directory ? new HashMap<>() : null;
         }
     }
 }

src/main/java/dan200/computercraft/core/filesystem/FileSystemWrapper.java

@@ -0,0 +1,42 @@
+package dan200.computercraft.core.filesystem;
+
+import javax.annotation.Nonnull;
+import java.io.Closeable;
+import java.io.IOException;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+
+/**
+ * An alternative closeable implementation that will free up resources in the filesystem.
+ *
+ * In an ideal world, we'd just wrap the closeable. However, as we do some {@code instanceof} checks
+ * on the stream, it's not really possible as it'd require numerous instances.
+ *
+ * @param <T> The stream to wrap.
+ */
+public class FileSystemWrapper<T extends Closeable> implements Closeable
+{
+    private final FileSystem fileSystem;
+    private final T closeable;
+    final WeakReference<FileSystemWrapper<?>> self;
+
+    FileSystemWrapper( FileSystem fileSystem, T closeable, ReferenceQueue<FileSystemWrapper<?>> queue )
+    {
+        this.fileSystem = fileSystem;
+        this.closeable = closeable;
+        this.self = new WeakReference<>( this, queue );
+    }
+
+    @Override
+    public void close() throws IOException
+    {
+        fileSystem.removeFile( this );
+        closeable.close();
+    }
+
+    @Nonnull
+    public T get()
+    {
+        return closeable;
+    }
+}

src/main/java/dan200/computercraft/core/filesystem/FileSystemWrapperMount.java

@@ -0,0 +1,220 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.core.filesystem;
+
+import dan200.computercraft.api.filesystem.IFileSystem;
+
+import javax.annotation.Nonnull;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.channels.Channels;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.channels.WritableByteChannel;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Function;
+
+public class FileSystemWrapperMount implements IFileSystem
+{
+    private final FileSystem m_filesystem;
+
+    public FileSystemWrapperMount( FileSystem m_filesystem )
+    {
+        this.m_filesystem = m_filesystem;
+    }
+
+    @Override
+    public void makeDirectory( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            m_filesystem.makeDir( path );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Override
+    public void delete( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            m_filesystem.delete( path );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Nonnull
+    @Override
+    public ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            // FIXME: Think of a better way of implementing this, so closing this will close on the computer.
+            return m_filesystem.openForRead( path, Function.identity() ).get();
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Nonnull
+    @Override
+    public WritableByteChannel openChannelForWrite( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            return m_filesystem.openForWrite( path, false, Function.identity() ).get();
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Nonnull
+    @Override
+    public WritableByteChannel openChannelForAppend( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            return m_filesystem.openForWrite( path, true, Function.identity() ).get();
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Nonnull
+    @Override
+    @Deprecated
+    public InputStream openForRead( @Nonnull String path ) throws IOException
+    {
+        return Channels.newInputStream( openChannelForRead( path ) );
+    }
+
+    @Nonnull
+    @Override
+    @Deprecated
+    public OutputStream openForWrite( @Nonnull String path ) throws IOException
+    {
+        return Channels.newOutputStream( openChannelForWrite( path ) );
+    }
+
+    @Nonnull
+    @Override
+    @Deprecated
+    public OutputStream openForAppend( @Nonnull String path ) throws IOException
+    {
+        return Channels.newOutputStream( openChannelForAppend( path ) );
+    }
+
+    @Override
+    public long getRemainingSpace() throws IOException
+    {
+        try
+        {
+            return m_filesystem.getFreeSpace( "/" );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Override
+    public boolean exists( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            return m_filesystem.exists( path );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Override
+    public boolean isDirectory( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            return m_filesystem.exists( path );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Override
+    public void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException
+    {
+        try
+        {
+            Collections.addAll( contents, m_filesystem.list( path ) );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Override
+    public long getSize( @Nonnull String path ) throws IOException
+    {
+        try
+        {
+            return m_filesystem.getSize( path );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Override
+    public String combine( String path, String child )
+    {
+        return m_filesystem.combine( path, child );
+    }
+
+    @Override
+    public void copy( String from, String to ) throws IOException
+    {
+        try
+        {
+            m_filesystem.copy( from, to );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+
+    @Override
+    public void move( String from, String to ) throws IOException
+    {
+        try
+        {
+            m_filesystem.move( from, to );
+        }
+        catch( FileSystemException e )
+        {
+            throw new IOException( e.getMessage() );
+        }
+    }
+}

src/main/java/dan200/computercraft/core/filesystem/JarMount.java

@@ -1,248 +0,0 @@
-/*
- * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2017. Do not distribute without permission.
- * Send enquiries to dratcliffe@gmail.com
- */
-
-package dan200.computercraft.core.filesystem;
-
-import dan200.computercraft.api.filesystem.IMount;
-
-import javax.annotation.Nonnull;
-import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.Enumeration;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipFile;
-
-public class JarMount implements IMount
-{    
-    private class FileInZip
-    {
-        private String m_path;
-        private boolean m_directory;
-        private long m_size;
-        private Map<String, FileInZip> m_children;
-        
-        public FileInZip( String path, boolean directory, long size )
-        {
-            m_path = path;
-            m_directory = directory;
-            m_size = m_directory ? 0 : size;
-            m_children = new LinkedHashMap<>();
-        }
-        
-        public String getPath()
-        {
-            return m_path;
-        }
-        
-        public boolean isDirectory()
-        {
-            return m_directory;
-        }
-                
-        public long getSize()
-        {
-            return m_size;
-        }
-        
-        public void list( List<String> contents )
-        {
-            contents.addAll( m_children.keySet() );
-        }
-                
-        public void insertChild( FileInZip child )
-        {
-            String localPath = FileSystem.toLocal( child.getPath(), m_path );
-            m_children.put( localPath, child );
-        }
-
-        public FileInZip getFile( String path ) 
-        {
-            // If we've reached the target, return this
-            if( path.equals( m_path ) )
-            {
-                return this;
-            }
-            
-            // Otherwise, get the next component of the path
-            String localPath = FileSystem.toLocal( path, m_path );
-            int slash = localPath.indexOf("/");
-            if( slash >= 0 )
-            {
-                localPath = localPath.substring( 0, slash );
-            }
-
-            // And recurse down using it
-            FileInZip subFile = m_children.get( localPath );
-            if( subFile != null )
-            {
-                return subFile.getFile( path );
-            }
-            
-            return null;
-        }
-        
-        public FileInZip getParent( String path )
-        {
-            if( path.length() == 0 )
-            {
-                return null;
-            }
-            
-            FileInZip file = getFile( FileSystem.getDirectory( path ) );
-            if( file.isDirectory() )
-            {
-                return file;
-            }
-            return null;
-        }
-    }
-    
-    private ZipFile m_zipFile;
-    private FileInZip m_root;
-    private String m_rootPath;
-
-    public JarMount( File jarFile, String subPath ) throws IOException
-    {
-        if( !jarFile.exists() || jarFile.isDirectory() )
-        {
-            throw new FileNotFoundException();
-        }
-        
-        // Open the zip file
-        try
-        {
-            m_zipFile = new ZipFile( jarFile );
-        }
-        catch( Exception e )
-        {
-            throw new IOException( "Error loading zip file" );
-        }
-    
-        if( m_zipFile.getEntry( subPath ) == null )
-        {
-            m_zipFile.close();
-            throw new IOException( "Zip does not contain path" );
-        }
-    
-        // Read in all the entries
-        Enumeration<? extends ZipEntry> zipEntries = m_zipFile.entries();
-        while( zipEntries.hasMoreElements() )
-        {
-            ZipEntry entry = zipEntries.nextElement();
-            String entryName = entry.getName();
-            if( entryName.startsWith( subPath ) )
-            {                    
-                entryName = FileSystem.toLocal( entryName, subPath );
-                if( m_root == null )
-                {
-                    if( entryName.equals( "" ) )
-                    {
-                        m_root = new FileInZip( entryName, entry.isDirectory(), entry.getSize() );
-                        m_rootPath = subPath;
-                        if( !m_root.isDirectory() )
-                        {
-                            break;
-                        }
-                    }
-                    else
-                    {
-                        // TODO: handle this case. The code currently assumes we find the root before anything else
-                    }
-                }
-                else
-                {
-                    FileInZip parent = m_root.getParent( entryName );
-                    if( parent != null )
-                    {
-                        parent.insertChild( new FileInZip( entryName, entry.isDirectory(), entry.getSize() ) );
-                    }
-                    else
-                    {
-                        // TODO: handle this case. The code currently assumes we find folders before their contents
-                    }
-                }
-            }            
-        }
-    }
-    
-    // IMount implementation
-    
-    @Override
-    public boolean exists( @Nonnull String path )
-    {
-        FileInZip file = m_root.getFile( path );
-        return file != null;
-    }
-    
-    @Override
-    public boolean isDirectory( @Nonnull String path )
-    {
-        FileInZip file = m_root.getFile( path );
-        if( file != null )
-        {
-            return file.isDirectory();
-        }
-        return false;
-    }
-    
-    @Override
-    public void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException
-    {
-        FileInZip file = m_root.getFile( path );
-        if( file != null && file.isDirectory() )
-        {
-            file.list( contents );
-        }
-        else
-        {
-            throw new IOException(  "/" + path + ": Not a directory" );
-        }
-    }
-    
-    @Override
-    public long getSize( @Nonnull String path ) throws IOException
-    {
-        FileInZip file = m_root.getFile( path );
-        if( file != null )
-        {
-            return file.getSize();
-        }
-        throw new IOException(  "/" + path + ": No such file" );
-    }
-
-    @Nonnull
-    @Override
-    public InputStream openForRead( @Nonnull String path ) throws IOException
-    {
-        FileInZip file = m_root.getFile( path );
-        if( file != null && !file.isDirectory() )
-        {
-            try
-            {
-                String fullPath = m_rootPath;
-                if( path.length() > 0 )
-                {
-                    fullPath = fullPath + "/" + path;
-                }
-                ZipEntry entry = m_zipFile.getEntry( fullPath );
-                if( entry != null )
-                {
-                    return m_zipFile.getInputStream( entry );
-                }
-            }
-            catch( Exception e )
-            {
-                // treat errors as non-existance of file
-            }
-        }
-        throw new IOException(  "/" + path  + ": No such file" );
-    }
-}

src/main/java/dan200/computercraft/core/filesystem/SubMount.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.filesystem.IMount;
 import javax.annotation.Nonnull;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.channels.ReadableByteChannel;
 import java.util.List;
 
 public class SubMount implements IMount
@@ -52,11 +53,19 @@ public class SubMount implements IMount
 
     @Nonnull
     @Override
+    @Deprecated
     public InputStream openForRead( @Nonnull String path ) throws IOException
     {
         return m_parent.openForRead( getFullPath( path ) );
     }
-    
+
+    @Nonnull
+    @Override
+    public ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
+    {
+        return m_parent.openChannelForRead( getFullPath( path ) );
+    }
+
     private String getFullPath( String path )
     {
         if( path.length() == 0 )

src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java

@@ -128,7 +128,7 @@ public class CobaltLuaMachine implements ILuaMachine
         LibFunction.bind( state, m_globals, PrefixLoader.class, new String[]{ "load", "loadstring" } );
 
         // Remove globals we don't want to expose
-        m_globals.rawset( "collectgarbage", Constants.NIL );
+        // m_globals.rawset( "collectgarbage", Constants.NIL );
         m_globals.rawset( "dofile", Constants.NIL );
         m_globals.rawset( "loadfile", Constants.NIL );
         m_globals.rawset( "print", Constants.NIL );

src/main/java/dan200/computercraft/core/terminal/Terminal.java

@@ -56,7 +56,7 @@ public class Terminal
         m_palette = new Palette();
     }
 
-    public void reset()
+    public synchronized void reset()
     {
         m_cursorColour = 0;
         m_cursorBackgroundColour = 15;
@@ -76,7 +76,7 @@ public class Terminal
         return m_height;
     }
     
-    public void resize( int width, int height )
+    public synchronized void resize( int width, int height )
     {
         if( width == m_width && height == m_height ) 
         {
@@ -189,7 +189,7 @@ public class Terminal
         return m_palette;
     }
 
-    public void blit( String text, String textColour, String backgroundColour )
+    public synchronized void blit( String text, String textColour, String backgroundColour )
     {
         int x = m_cursorX;
         int y = m_cursorY;
@@ -202,7 +202,7 @@ public class Terminal
         }
     }
 
-    public void write( String text )
+    public synchronized void write( String text )
     {
         int x = m_cursorX;
         int y = m_cursorY;
@@ -215,7 +215,7 @@ public class Terminal
         }
     }
     
-    public void scroll( int yDiff )
+    public synchronized void scroll( int yDiff )
     {
         if( yDiff != 0 )
         {
@@ -245,7 +245,7 @@ public class Terminal
         }
     }
     
-    public void clear()
+    public synchronized void clear()
     {
         for( int y = 0; y < m_height; ++y )
         {
@@ -256,7 +256,7 @@ public class Terminal
         m_changed = true;
     }
 
-    public void clearLine()
+    public synchronized void clearLine()
     {
         int y = m_cursorY;
         if( y >= 0 && y < m_height )
@@ -268,7 +268,7 @@ public class Terminal
         }
     }
         
-    public TextBuffer getLine( int y )
+    public synchronized TextBuffer getLine( int y )
     {
         if( y >= 0 && y < m_height )
         {
@@ -277,7 +277,7 @@ public class Terminal
         return null;
     }
 
-    public void setLine( int y, String text, String textColour, String backgroundColour )
+    public synchronized void setLine( int y, String text, String textColour, String backgroundColour )
     {
         m_text[y].write( text );
         m_textColour[y].write( textColour );
@@ -285,7 +285,7 @@ public class Terminal
         m_changed = true;
     }
     
-    public TextBuffer getTextColourLine( int y )
+    public synchronized TextBuffer getTextColourLine( int y )
     {
         if( y>=0 && y<m_height )
         {
@@ -294,7 +294,7 @@ public class Terminal
         return null;
     }
 
-    public TextBuffer getBackgroundColourLine( int y )
+    public synchronized TextBuffer getBackgroundColourLine( int y )
     {
         if( y>=0 && y<m_height )
         {
@@ -318,7 +318,7 @@ public class Terminal
         m_changed = false;
     }
 
-    public NBTTagCompound writeToNBT( NBTTagCompound nbttagcompound )
+    public synchronized NBTTagCompound writeToNBT( NBTTagCompound nbttagcompound )
     {
         nbttagcompound.setInteger( "term_cursorX", m_cursorX );
         nbttagcompound.setInteger( "term_cursorY", m_cursorY );
@@ -338,7 +338,7 @@ public class Terminal
         return nbttagcompound;
     }
 
-    public void readFromNBT( NBTTagCompound nbttagcompound )
+    public synchronized void readFromNBT( NBTTagCompound nbttagcompound )
     {
         m_cursorX = nbttagcompound.getInteger( "term_cursorX" );
         m_cursorY = nbttagcompound.getInteger( "term_cursorY" );

src/main/java/dan200/computercraft/core/tracking/ComputerTracker.java

@@ -0,0 +1,117 @@
+package dan200.computercraft.core.tracking;
+
+import dan200.computercraft.core.computer.Computer;
+import gnu.trove.map.hash.TObjectLongHashMap;
+
+import javax.annotation.Nullable;
+import java.lang.ref.WeakReference;
+
+public class ComputerTracker
+{
+    private final WeakReference<Computer> computer;
+    private final int computerId;
+
+    private long tasks;
+    private long totalTime;
+    private long maxTime;
+
+    private long serverCount;
+    private long serverTime;
+
+    private final TObjectLongHashMap<TrackingField> fields;
+
+    public ComputerTracker( Computer computer )
+    {
+        this.computer = new WeakReference<>( computer );
+        this.computerId = computer.getID();
+        this.fields = new TObjectLongHashMap<>();
+    }
+
+    ComputerTracker( ComputerTracker timings )
+    {
+        this.computer = timings.computer;
+        this.computerId = timings.computerId;
+
+        this.tasks = timings.tasks;
+        this.totalTime = timings.totalTime;
+        this.maxTime = timings.maxTime;
+
+        this.serverCount = timings.serverCount;
+        this.serverTime = timings.serverTime;
+
+        this.fields = new TObjectLongHashMap<>( timings.fields );
+    }
+
+    @Nullable
+    public Computer getComputer()
+    {
+        return computer.get();
+    }
+
+    public int getComputerId()
+    {
+        return computerId;
+    }
+
+    public long getTasks()
+    {
+        return tasks;
+    }
+
+    public long getTotalTime()
+    {
+        return totalTime;
+    }
+
+    public long getMaxTime()
+    {
+        return maxTime;
+    }
+
+    public long getAverage()
+    {
+        return totalTime / tasks;
+    }
+
+    void addTaskTiming( long time )
+    {
+        tasks++;
+        totalTime += time;
+        if( time > maxTime ) maxTime = time;
+    }
+
+    void addMainTiming( long time )
+    {
+        serverCount++;
+        serverTime += time;
+    }
+
+    void addValue( TrackingField field, long change )
+    {
+        synchronized( fields )
+        {
+            fields.adjustOrPutValue( field, change, change );
+        }
+    }
+
+    public long get( TrackingField field )
+    {
+        if( field == TrackingField.TASKS ) return tasks;
+        if( field == TrackingField.MAX_TIME ) return maxTime;
+        if( field == TrackingField.TOTAL_TIME ) return totalTime;
+        if( field == TrackingField.AVERAGE_TIME ) return tasks == 0 ? 0 : totalTime / tasks;
+
+        if( field == TrackingField.SERVER_COUNT ) return serverCount;
+        if( field == TrackingField.SERVER_TIME ) return serverTime;
+
+        synchronized( fields )
+        {
+            return fields.get( field );
+        }
+    }
+
+    public String getFormatted( TrackingField field )
+    {
+        return field.format( get( field ) );
+    }
+}

src/main/java/dan200/computercraft/core/tracking/Tracker.java

@@ -0,0 +1,49 @@
+package dan200.computercraft.core.tracking;
+
+import dan200.computercraft.core.computer.Computer;
+
+public interface Tracker
+{
+    @Deprecated
+    default void addTiming( Computer computer, long time )
+    {
+    }
+
+    /**
+     * Report how long a task executed on the computer thread took.
+     *
+     * Computer thread tasks include events or a computer being turned on/off.
+     *
+     * @param computer The computer processing this task
+     * @param time     The time taken for this task.
+     */
+    default void addTaskTiming( Computer computer, long time )
+    {
+        //noinspection deprecation
+        addTiming( computer, time );
+    }
+
+    /**
+     * Report how long a task executed on the server thread took.
+     *
+     * Server tasks include actions performed by peripherals.
+     *
+     * @param computer The computer processing this task
+     * @param time     The time taken for this task.
+     */
+    default void addServerTiming( Computer computer, long time )
+    {
+    }
+
+    /**
+     * Increment an arbitrary field by some value. Implementations may track how often this is called
+     * as well as the change, to compute some level of "average".
+     *
+     * @param computer The computer to increment
+     * @param field    The field to increment.
+     * @param change   The amount to increment said field by.
+     */
+    default void addValue( Computer computer, TrackingField field, long change )
+    {
+    }
+}

src/main/java/dan200/computercraft/core/tracking/Tracking.java

@@ -0,0 +1,80 @@
+package dan200.computercraft.core.tracking;
+
+import dan200.computercraft.core.computer.Computer;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class Tracking
+{
+    static final AtomicInteger tracking = new AtomicInteger( 0 );
+
+    private static final Object lock = new Object();
+    private static final HashMap<UUID, TrackingContext> contexts = new HashMap<>();
+    private static final List<Tracker> trackers = new ArrayList<>();
+
+    public static TrackingContext getContext( UUID uuid )
+    {
+        synchronized( lock )
+        {
+            TrackingContext context = contexts.get( uuid );
+            if( context == null ) contexts.put( uuid, context = new TrackingContext() );
+            return context;
+        }
+    }
+
+    public static void add( Tracker tracker )
+    {
+        synchronized( lock )
+        {
+            trackers.add( tracker );
+            tracking.incrementAndGet();
+        }
+    }
+
+    public static void addTaskTiming( Computer computer, long time )
+    {
+        if( tracking.get() == 0 ) return;
+
+        synchronized( contexts )
+        {
+            for( TrackingContext context : contexts.values() ) context.addTaskTiming( computer, time );
+            for( Tracker tracker : trackers ) tracker.addTaskTiming( computer, time );
+        }
+    }
+
+    public static void addServerTiming( Computer computer, long time )
+    {
+        if( tracking.get() == 0 ) return;
+
+        synchronized( contexts )
+        {
+            for( TrackingContext context : contexts.values() ) context.addServerTiming( computer, time );
+            for( Tracker tracker : trackers ) tracker.addServerTiming( computer, time );
+        }
+    }
+
+    public static void addValue( Computer computer, TrackingField field, long change )
+    {
+        if( tracking.get() == 0 ) return;
+
+        synchronized( lock )
+        {
+            for( TrackingContext context : contexts.values() ) context.addValue( computer, field, change );
+            for( Tracker tracker : trackers ) tracker.addValue( computer, field, change );
+        }
+    }
+
+    public static void reset()
+    {
+        synchronized( lock )
+        {
+            contexts.clear();
+            trackers.clear();
+            tracking.set( 0 );
+        }
+    }
+}

src/main/java/dan200/computercraft/core/tracking/TrackingContext.java

@@ -0,0 +1,111 @@
+package dan200.computercraft.core.tracking;
+
+import com.google.common.collect.MapMaker;
+import dan200.computercraft.core.computer.Computer;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Tracks timing information about computers, including how long they ran for
+ * and the number of events they handled.
+ *
+ * Note that this <em>will</em> track computers which have been deleted (hence
+ * the presence of {@link #timingLookup} and {@link #timings}
+ */
+public class TrackingContext implements Tracker
+{
+    private boolean tracking = false;
+
+    private final List<ComputerTracker> timings = new ArrayList<>();
+    private final Map<Computer, ComputerTracker> timingLookup = new MapMaker().weakKeys().makeMap();
+
+    public synchronized void start()
+    {
+        if( !tracking ) Tracking.tracking.incrementAndGet();
+        tracking = true;
+
+        timings.clear();
+        timingLookup.clear();
+    }
+
+    public synchronized boolean stop()
+    {
+        if( !tracking ) return false;
+
+        Tracking.tracking.decrementAndGet();
+        tracking = false;
+        timingLookup.clear();
+        return true;
+    }
+
+    public synchronized List<ComputerTracker> getImmutableTimings()
+    {
+        ArrayList<ComputerTracker> timings = new ArrayList<>( this.timings.size() );
+        for( ComputerTracker timing : this.timings ) timings.add( new ComputerTracker( timing ) );
+        return timings;
+    }
+
+    public synchronized List<ComputerTracker> getTimings()
+    {
+        return new ArrayList<>( timings );
+    }
+
+    @Override
+    public void addTaskTiming( Computer computer, long time )
+    {
+        if( !tracking ) return;
+
+        synchronized( this )
+        {
+            ComputerTracker computerTimings = timingLookup.get( computer );
+            if( computerTimings == null )
+            {
+                computerTimings = new ComputerTracker( computer );
+                timingLookup.put( computer, computerTimings );
+                timings.add( computerTimings );
+            }
+
+            computerTimings.addTaskTiming( time );
+        }
+    }
+
+    @Override
+    public void addServerTiming( Computer computer, long time )
+    {
+        if( !tracking ) return;
+
+        synchronized( this )
+        {
+            ComputerTracker computerTimings = timingLookup.get( computer );
+            if( computerTimings == null )
+            {
+                computerTimings = new ComputerTracker( computer );
+                timingLookup.put( computer, computerTimings );
+                timings.add( computerTimings );
+            }
+
+            computerTimings.addMainTiming( time );
+        }
+    }
+
+    @Override
+    public void addValue( Computer computer, TrackingField field, long change )
+    {
+        if( !tracking ) return;
+
+        synchronized( this )
+        {
+            ComputerTracker computerTimings = timingLookup.get( computer );
+            if( computerTimings == null )
+            {
+                computerTimings = new ComputerTracker( computer );
+                timingLookup.put( computer, computerTimings );
+                timings.add( computerTimings );
+            }
+
+            computerTimings.addValue( field, change );
+        }
+    }
+}

src/main/java/dan200/computercraft/core/tracking/TrackingField.java

@@ -0,0 +1,88 @@
+package dan200.computercraft.core.tracking;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.LongFunction;
+
+public class TrackingField
+{
+    private static final Map<String, TrackingField> fields = new HashMap<>();
+
+    public static final TrackingField TASKS = TrackingField.of( "tasks", "Tasks", x -> String.format( "%4d", x ) );
+    public static final TrackingField TOTAL_TIME = TrackingField.of( "total", "Total time", x -> String.format( "%7.1fms", x / 1e6 ) );
+    public static final TrackingField AVERAGE_TIME = TrackingField.of( "average", "Average time", x -> String.format( "%4.1fms", x / 1e6 ) );
+    public static final TrackingField MAX_TIME = TrackingField.of( "max", "Max time", x -> String.format( "%5.1fms", x / 1e6 ) );
+
+    public static final TrackingField SERVER_COUNT = TrackingField.of( "server_count", "Server task count", x -> String.format( "%4d", x ) );
+    public static final TrackingField SERVER_TIME = TrackingField.of( "server_time", "Server task time", x -> String.format( "%7.1fms", x / 1e6 ) );
+
+    public static final TrackingField PERIPHERAL_OPS = TrackingField.of( "peripheral", "Peripheral calls", TrackingField::formatDefault );
+    public static final TrackingField FS_OPS = TrackingField.of( "fs", "Filesystem operations", TrackingField::formatDefault );
+    public static final TrackingField TURTLE_OPS = TrackingField.of( "turtle", "Turtle operations", TrackingField::formatDefault );
+
+    public static final TrackingField HTTP_REQUESTS = TrackingField.of( "http", "HTTP requests", TrackingField::formatDefault );
+    public static final TrackingField HTTP_UPLOAD = TrackingField.of( "http_upload", "HTTP upload", TrackingField::formatBytes );
+    public static final TrackingField HTTP_DOWNLOAD = TrackingField.of( "http_download", "HTTT download", TrackingField::formatBytes );
+
+    public static final TrackingField WEBSOCKET_INCOMING = TrackingField.of( "websocket_incoming", "Websocket incoming", TrackingField::formatBytes );
+    public static final TrackingField WEBSOCKET_OUTGOING = TrackingField.of( "websocket_outgoing", "Websocket outgoing", TrackingField::formatBytes );
+
+    private final String id;
+    private final String displayName;
+    private final LongFunction<String> format;
+
+    public String id()
+    {
+        return id;
+    }
+
+    public String displayName()
+    {
+        return displayName;
+    }
+
+    private TrackingField( String id, String displayName, LongFunction<String> format )
+    {
+        this.id = id;
+        this.displayName = displayName;
+        this.format = format;
+    }
+
+    public String format( long value )
+    {
+        return format.apply( value );
+    }
+
+    public static TrackingField of( String id, String displayName, LongFunction<String> format )
+    {
+        TrackingField field = new TrackingField( id, displayName, format );
+        fields.put( id, field );
+        return field;
+    }
+
+    public static Map<String, TrackingField> fields()
+    {
+        return Collections.unmodifiableMap( fields );
+    }
+
+    private static String formatDefault( long value )
+    {
+        return String.format( "%6d", value );
+    }
+
+    /**
+     * So technically a kibibyte, but let's not argue here.
+     */
+    private static final int KILOBYTE_SIZE = 1024;
+
+    private static final String SI_PREFIXES = "KMGT";
+
+    private static String formatBytes( long bytes )
+    {
+        if( bytes < 1024 ) return String.format( "%10d B", bytes );
+        int exp = (int) (Math.log( bytes ) / Math.log( KILOBYTE_SIZE ));
+        if( exp > SI_PREFIXES.length() ) exp = SI_PREFIXES.length();
+        return String.format( "%10.1f %siB", bytes / Math.pow( KILOBYTE_SIZE, exp ), SI_PREFIXES.charAt( exp - 1 ) );
+    }
+}

src/main/java/dan200/computercraft/server/proxy/ComputerCraftProxyServer.java

@@ -8,6 +8,8 @@ package dan200.computercraft.server.proxy;
 
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.shared.computer.blocks.TileComputer;
+import dan200.computercraft.shared.computer.core.ComputerFamily;
+import dan200.computercraft.shared.computer.core.IComputer;
 import dan200.computercraft.shared.network.ComputerCraftPacket;
 import dan200.computercraft.shared.peripheral.diskdrive.TileDiskDrive;
 import dan200.computercraft.shared.peripheral.printer.TilePrinter;
@@ -97,6 +99,12 @@ public class ComputerCraftProxyServer extends ComputerCraftProxyCommon
         return null;
     }
 
+    @Override
+    public Object getComputerGUI( IComputer computer, int width, int height, ComputerFamily family )
+    {
+        return null;
+    }
+
     @Override
     public File getWorldDir( World world )
     {

src/main/java/dan200/computercraft/shared/command/CommandComputerCraft.java

@@ -0,0 +1,532 @@
+package dan200.computercraft.shared.command;
+
+import com.google.common.collect.Sets;
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.core.computer.Computer;
+import dan200.computercraft.core.tracking.ComputerTracker;
+import dan200.computercraft.core.tracking.Tracking;
+import dan200.computercraft.core.tracking.TrackingContext;
+import dan200.computercraft.core.tracking.TrackingField;
+import dan200.computercraft.shared.command.framework.*;
+import dan200.computercraft.shared.computer.core.ServerComputer;
+import net.minecraft.command.CommandBase;
+import net.minecraft.command.CommandException;
+import net.minecraft.command.ICommandSender;
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.text.ITextComponent;
+import net.minecraft.util.text.TextComponentString;
+import net.minecraft.world.World;
+
+import javax.annotation.Nonnull;
+import java.util.*;
+import java.util.function.Consumer;
+
+import static dan200.computercraft.shared.command.framework.ChatHelpers.*;
+
+public final class CommandComputerCraft extends CommandDelegate
+{
+    public static final UUID SYSTEM_UUID = new UUID( 0, 0 );
+
+    private static final int DUMP_LIST_ID = 5373952;
+    private static final int DUMP_SINGLE_ID = 1844510720;
+    private static final int TRACK_ID = 373882880;
+
+    public CommandComputerCraft()
+    {
+        super( create() );
+    }
+
+    private static ISubCommand create()
+    {
+        CommandRoot root = new CommandRoot(
+            "computercraft", "Various commands for controlling computers.",
+            "The /computercraft command provides various debugging and administrator tools for controlling and " +
+                "interacting with computers."
+        );
+
+        root.register( new SubCommandBase(
+            "dump", "[id]", "Display the status of computers.", UserLevel.OWNER_OP,
+            "Display the status of all computers or specific information about one computer. You can specify the " +
+                "computer's instance id (e.g. 123), computer id (e.g #123) or label (e.g. \"@My Computer\")."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                if( arguments.size() == 0 )
+                {
+                    TextTable table = new TextTable( DUMP_LIST_ID, "Computer", "On", "Position" );
+
+                    List<ServerComputer> computers = new ArrayList<>( ComputerCraft.serverComputerRegistry.getComputers() );
+
+                    // Unless we're on a server, limit the number of rows we can send.
+                    if( !(context.getSender() instanceof MinecraftServer) )
+                    {
+                        World world = context.getSender().getEntityWorld();
+                        BlockPos pos = context.getSender().getPosition();
+
+                        computers.sort( ( a, b ) -> {
+                            if( a.getWorld() == b.getWorld() && a.getWorld() == world )
+                            {
+                                return Double.compare( a.getPosition().distanceSq( pos ), b.getPosition().distanceSq( pos ) );
+                            }
+                            else if( a.getWorld() == world )
+                            {
+                                return -1;
+                            }
+                            else if( b.getWorld() == world )
+                            {
+                                return 1;
+                            }
+                            else
+                            {
+                                return Integer.compare( a.getInstanceID(), b.getInstanceID() );
+                            }
+                        } );
+                    }
+
+                    for( ServerComputer computer : computers )
+                    {
+                        table.addRow(
+                            linkComputer( context, computer, computer.getID() ),
+                            bool( computer.isOn() ),
+                            linkPosition( context, computer )
+                        );
+                    }
+
+                    table.displayTo( context.getSender() );
+                }
+                else if( arguments.size() == 1 )
+                {
+                    ServerComputer computer = ComputerSelector.getComputer( arguments.get( 0 ) );
+
+                    TextTable table = new TextTable( DUMP_SINGLE_ID );
+                    table.addRow( header( "Instance" ), text( Integer.toString( computer.getInstanceID() ) ) );
+                    table.addRow( header( "Id" ), text( Integer.toString( computer.getID() ) ) );
+                    table.addRow( header( "Label" ), text( computer.getLabel() ) );
+                    table.addRow( header( "On" ), bool( computer.isOn() ) );
+                    table.addRow( header( "Position" ), linkPosition( context, computer ) );
+                    table.addRow( header( "Family" ), text( computer.getFamily().toString() ) );
+
+                    for( int i = 0; i < 6; i++ )
+                    {
+                        IPeripheral peripheral = computer.getPeripheral( i );
+                        if( peripheral != null )
+                        {
+                            table.addRow( header( "Peripheral " + Computer.s_sideNames[i] ), text( peripheral.getType() ) );
+                        }
+                    }
+
+                    table.displayTo( context.getSender() );
+                }
+                else
+                {
+                    throw new CommandException( context.getFullUsage() );
+                }
+            }
+
+            @Nonnull
+            @Override
+            public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                return arguments.size() == 1
+                    ? ComputerSelector.completeComputer( arguments.get( 0 ) )
+                    : Collections.emptyList();
+            }
+        } );
+
+        root.register( new SubCommandBase(
+            "shutdown", "[ids...]", "Shutdown computers remotely.", UserLevel.OWNER_OP,
+            "Shutdown the listed computers or all if none are specified. You can specify the computer's instance id " +
+                "(e.g. 123), computer id (e.g #123) or label (e.g. \"@My Computer\")."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                withComputers( arguments, computers -> {
+                    int shutdown = 0;
+                    for( ServerComputer computer : computers )
+                    {
+                        if( computer.isOn() ) shutdown++;
+                        computer.unload();
+                    }
+                    context.getSender().sendMessage( text( "Shutdown " + shutdown + " / " + computers.size() + " computers" ) );
+                } );
+            }
+
+            @Nonnull
+            @Override
+            public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                return arguments.size() == 0
+                    ? Collections.emptyList()
+                    : ComputerSelector.completeComputer( arguments.get( arguments.size() - 1 ) );
+            }
+        } );
+
+        root.register( new SubCommandBase(
+            "turn-on", "ids...", "Turn computers on remotely.", UserLevel.OWNER_OP,
+            "Turn on the listed computers. You can specify the computer's instance id (e.g. 123), computer id (e.g #123) " +
+                "or label (e.g. \"@My Computer\")."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                withComputers( arguments, computers -> {
+                    int on = 0;
+                    for( ServerComputer computer : computers )
+                    {
+                        if( !computer.isOn() ) on++;
+                        computer.turnOn();
+                    }
+                    context.getSender().sendMessage( text( "Turned on " + on + " / " + computers.size() + " computers" ) );
+                } );
+            }
+
+            @Nonnull
+            @Override
+            public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                return arguments.size() == 0
+                    ? Collections.emptyList()
+                    : ComputerSelector.completeComputer( arguments.get( arguments.size() - 1 ) );
+            }
+        } );
+
+        root.register( new SubCommandBase(
+            "tp", "<id>", "Teleport to a specific computer.", UserLevel.OP,
+            "Teleport to the location of a computer. You can either specify the computer's instance " +
+                "id (e.g. 123) or computer id (e.g #123)."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                if( arguments.size() != 1 ) throw new CommandException( context.getFullUsage() );
+
+                ServerComputer computer = ComputerSelector.getComputer( arguments.get( 0 ) );
+                World world = computer.getWorld();
+                BlockPos pos = computer.getPosition();
+
+                if( world == null || pos == null ) throw new CommandException( "Cannot locate computer in world" );
+
+                ICommandSender sender = context.getSender();
+                if( !(sender instanceof Entity) ) throw new CommandException( "Sender is not an entity" );
+
+                if( sender instanceof EntityPlayerMP )
+                {
+                    EntityPlayerMP entity = (EntityPlayerMP) sender;
+                    if( entity.getEntityWorld() != world )
+                    {
+                        context.getServer().getPlayerList().changePlayerDimension( entity, world.provider.getDimension() );
+                    }
+
+                    entity.setPositionAndUpdate( pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5 );
+                }
+                else
+                {
+                    Entity entity = (Entity) sender;
+                    if( entity.getEntityWorld() != world )
+                    {
+                        entity.changeDimension( world.provider.getDimension() );
+                    }
+
+                    entity.setLocationAndAngles(
+                        pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5,
+                        entity.rotationYaw, entity.rotationPitch
+                    );
+                }
+            }
+
+            @Nonnull
+            @Override
+            public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                return arguments.size() == 1
+                    ? ComputerSelector.completeComputer( arguments.get( 0 ) )
+                    : Collections.emptyList();
+            }
+        } );
+
+        root.register( new SubCommandBase(
+            "view", "<id>", "View the terminal of a computer.", UserLevel.OP,
+            "Open the terminal of a computer, allowing remote control of a computer. This does not provide access to " +
+                "turtle's inventories. You can either specify the computer's instance id (e.g. 123) or computer id (e.g #123)."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                if( arguments.size() != 1 ) throw new CommandException( context.getFullUsage() );
+
+                ICommandSender sender = context.getSender();
+                if( !(sender instanceof EntityPlayerMP) )
+                {
+                    throw new CommandException( "Cannot open terminal for non-player" );
+                }
+
+                ServerComputer computer = ComputerSelector.getComputer( arguments.get( 0 ) );
+                ComputerCraft.openComputerGUI( (EntityPlayerMP) sender, computer );
+            }
+
+            @Nonnull
+            @Override
+            public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                return arguments.size() == 1
+                    ? ComputerSelector.completeComputer( arguments.get( 0 ) )
+                    : Collections.emptyList();
+            }
+        } );
+
+        CommandRoot track = new CommandRoot( "track", "Track execution times for computers.",
+            "Track how long computers execute for, as well as how many events they handle. This presents information in " +
+                "a similar way to /forge track and can be useful for diagnosing lag." );
+        root.register( track );
+
+        track.register( new SubCommandBase(
+            "start", "Start tracking all computers", UserLevel.OWNER_OP,
+            "Start tracking all computers' execution times and event counts. This will discard the results of previous runs."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                getTimingContext( context ).start();
+
+                String stopCommand = "/" + context.parent().getFullPath() + " stop";
+                context.getSender().sendMessage( list(
+                    text( "Run " ),
+                    link( text( stopCommand ), stopCommand, "Click to stop tracking" ),
+                    text( " to stop tracking and view the results" )
+                ) );
+            }
+        } );
+
+        track.register( new SubCommandBase(
+            "stop", "Stop tracking all computers", UserLevel.OWNER_OP,
+            "Stop tracking all computers' events and execution times"
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                TrackingContext timings = getTimingContext( context );
+                if( !timings.stop() ) throw new CommandException( "Tracking not enabled" );
+                displayTimings( context, timings.getImmutableTimings(), TrackingField.AVERAGE_TIME );
+            }
+        } );
+
+        track.register( new SubCommandBase(
+            "dump", "[kind]", "Dump the latest track results", UserLevel.OWNER_OP,
+            "Dump the latest results of computer tracking."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                TrackingField field = TrackingField.AVERAGE_TIME;
+                if( arguments.size() >= 1 )
+                {
+                    field = TrackingField.fields().get( arguments.get( 0 ) );
+                    if( field == null ) throw new CommandException( "Unknown field '" + arguments.get( 0 ) + "'" );
+                }
+
+                displayTimings( context, getTimingContext( context ).getImmutableTimings(), field );
+            }
+
+            @Nonnull
+            @Override
+            public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                if( arguments.size() == 1 )
+                {
+                    String match = arguments.get( 0 );
+
+                    List<String> out = new ArrayList<>();
+                    for( String key : TrackingField.fields().keySet() )
+                    {
+                        if( CommandBase.doesStringStartWith( match, key ) ) out.add( key );
+                    }
+
+                    out.sort( Comparator.naturalOrder() );
+                    return out;
+                }
+                else
+                {
+                    return super.getCompletion( context, arguments );
+                }
+            }
+        } );
+
+        root.register( new SubCommandBase(
+            "reload", "Reload the ComputerCraft config file", UserLevel.OWNER_OP,
+            "Reload the ComputerCraft config file"
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                ComputerCraft.loadConfig();
+                ComputerCraft.syncConfig();
+                context.getSender().sendMessage( new TextComponentString( "Reloaded config" ) );
+            }
+        } );
+
+
+        return root;
+    }
+
+    private static ITextComponent linkComputer( CommandContext context, ServerComputer serverComputer, int computerId )
+    {
+        ITextComponent out = new TextComponentString( "" );
+
+        // Append the computer instance
+        if( serverComputer == null )
+        {
+            out.appendSibling( text( "?" ) );
+        }
+        else
+        {
+            out.appendSibling( link(
+                text( Integer.toString( serverComputer.getInstanceID() ) ),
+                "/computercraft dump " + serverComputer.getInstanceID(),
+                "View more info about this computer"
+            ) );
+        }
+
+        // And ID
+        out.appendText( " (id " + computerId + ")" );
+
+        // And, if we're a player, some useful links
+        if( serverComputer != null && UserLevel.OP.canExecute( context ) && context.fromPlayer() )
+        {
+            out
+                .appendText( " " )
+                .appendSibling( link(
+                    text( "\u261b" ),
+                    "/computercraft tp " + serverComputer.getInstanceID(),
+                    "Teleport to this computer"
+                ) )
+                .appendText( " " )
+                .appendSibling( link(
+                    text( "\u20e2" ),
+                    "/computercraft view " + serverComputer.getInstanceID(),
+                    "View this computer"
+                ) );
+        }
+
+        return out;
+    }
+
+    private static ITextComponent linkPosition( CommandContext context, ServerComputer computer )
+    {
+        if( UserLevel.OP.canExecute( context ) )
+        {
+            return link(
+                position( computer.getPosition() ),
+                "/computercraft tp " + computer.getInstanceID(),
+                "Teleport to this computer"
+            );
+        }
+        else
+        {
+            return position( computer.getPosition() );
+        }
+    }
+
+    private static TrackingContext getTimingContext( CommandContext context )
+    {
+        Entity entity = context.getSender().getCommandSenderEntity();
+        if( entity instanceof EntityPlayerMP )
+        {
+            return Tracking.getContext( entity.getUniqueID() );
+        }
+        else
+        {
+            return Tracking.getContext( SYSTEM_UUID );
+        }
+    }
+
+    private static void displayTimings( CommandContext context, List<ComputerTracker> timings, TrackingField field ) throws CommandException
+    {
+        if( timings.isEmpty() ) throw new CommandException( "No timings available" );
+
+        Map<Computer, ServerComputer> lookup = new HashMap<>();
+        int maxId = 0, maxInstance = 0;
+        for( ServerComputer server : ComputerCraft.serverComputerRegistry.getComputers() )
+        {
+            lookup.put( server.getComputer(), server );
+
+            if( server.getInstanceID() > maxInstance ) maxInstance = server.getInstanceID();
+            if( server.getID() > maxId ) maxId = server.getID();
+        }
+
+        timings.sort( Comparator.<ComputerTracker, Long>comparing( x -> x.get( field ) ).reversed() );
+
+        boolean defaultLayout = field == TrackingField.TASKS || field == TrackingField.TOTAL_TIME
+            || field == TrackingField.AVERAGE_TIME || field == TrackingField.MAX_TIME;
+
+
+        TextTable table = defaultLayout
+            ? new TextTable( TRACK_ID, "Computer", "Tasks", "Total", "Average", "Maximum" )
+            : new TextTable( TRACK_ID, "Computer", field.displayName() );
+
+        for( ComputerTracker entry : timings )
+        {
+            Computer computer = entry.getComputer();
+            ServerComputer serverComputer = computer == null ? null : lookup.get( computer );
+
+            ITextComponent computerComponent = linkComputer( context, serverComputer, entry.getComputerId() );
+
+            if( defaultLayout )
+            {
+                table.addRow(
+                    computerComponent,
+                    text( entry.getFormatted( TrackingField.TASKS ) ),
+                    text( entry.getFormatted( TrackingField.TOTAL_TIME ) ),
+                    text( entry.getFormatted( TrackingField.AVERAGE_TIME ) ),
+                    text( entry.getFormatted( TrackingField.MAX_TIME ) )
+                );
+            }
+            else
+            {
+                table.addRow( computerComponent, text( entry.getFormatted( field ) ) );
+            }
+        }
+
+        table.displayTo( context.getSender() );
+    }
+
+    private static void withComputers( List<String> selectors, Consumer<Collection<ServerComputer>> action ) throws CommandException
+    {
+        Set<ServerComputer> computers = Sets.newHashSet();
+        List<String> failed = new ArrayList<>();
+        if( selectors.isEmpty() )
+        {
+            computers.addAll( ComputerCraft.serverComputerRegistry.getComputers() );
+        }
+        else
+        {
+            for( String selector : selectors )
+            {
+                List<ServerComputer> selected = ComputerSelector.getComputers( selector );
+                computers.addAll( selected );
+                if( selected.isEmpty() ) failed.add( selector );
+            }
+        }
+
+        action.accept( computers );
+
+        if( !failed.isEmpty() )
+        {
+            throw new CommandException( "Could not find computers matching " + String.join( ", ", failed ) );
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/command/ComputerSelector.java

@@ -0,0 +1,157 @@
+package dan200.computercraft.shared.command;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.computer.core.ComputerFamily;
+import dan200.computercraft.shared.computer.core.ServerComputer;
+import net.minecraft.command.CommandException;
+
+import java.util.*;
+import java.util.function.Predicate;
+
+public final class ComputerSelector
+{
+    private static List<ServerComputer> getComputers( Predicate<ServerComputer> predicate ) throws CommandException
+    {
+        // We copy it to prevent concurrent modifications.
+        ArrayList<ServerComputer> computers = new ArrayList<>( ComputerCraft.serverComputerRegistry.getComputers() );
+        computers.removeIf( predicate.negate() );
+        return computers;
+    }
+
+    public static ServerComputer getComputer( String selector ) throws CommandException
+    {
+        List<ServerComputer> computers = getComputers( selector );
+        if( computers.size() == 0 )
+        {
+            throw new CommandException( "No computer matching " + selector );
+        }
+        else if( computers.size() == 1 )
+        {
+            return computers.get( 0 );
+        }
+        else
+        {
+            StringBuilder builder = new StringBuilder( "Multiple computers matching " )
+                .append( selector ).append( " (instances " );
+
+            for( int i = 0; i < computers.size(); i++ )
+            {
+                if( i > 0 ) builder.append( ", " );
+                builder.append( computers.get( i ).getInstanceID() );
+            }
+            builder.append( ")" );
+
+            throw new CommandException( builder.toString() );
+        }
+    }
+
+    public static List<ServerComputer> getComputers( String selector ) throws CommandException
+    {
+        if( selector.length() > 0 && selector.charAt( 0 ) == '#' )
+        {
+            selector = selector.substring( 1 );
+
+            int id;
+            try
+            {
+                id = Integer.parseInt( selector );
+            }
+            catch( NumberFormatException e )
+            {
+                throw new CommandException( "'" + selector + "' is not a valid number" );
+            }
+
+            return getComputers( x -> x.getID() == id );
+        }
+        else if( selector.length() > 0 && selector.charAt( 0 ) == '@' )
+        {
+            String label = selector.substring( 1 );
+            return getComputers( x -> Objects.equals( label, x.getLabel() ) );
+        }
+        else if( selector.length() > 0 && selector.charAt( 0 ) == '~' )
+        {
+            String familyName = selector.substring( 1 );
+            return getComputers( x -> x.getFamily().name().equalsIgnoreCase( familyName ) );
+        }
+        else
+        {
+            int instance;
+            try
+            {
+                instance = Integer.parseInt( selector );
+            }
+            catch( NumberFormatException e )
+            {
+                throw new CommandException( "'" + selector + "' is not a valid number" );
+            }
+
+            ServerComputer computer = ComputerCraft.serverComputerRegistry.get( instance );
+            return computer == null ? Collections.emptyList() : Collections.singletonList( computer );
+        }
+    }
+
+    public static List<String> completeComputer( String selector )
+    {
+        TreeSet<String> options = Sets.newTreeSet();
+
+        // We copy it to prevent concurrent modifications.
+        List<ServerComputer> computers = Lists.newArrayList( ComputerCraft.serverComputerRegistry.getComputers() );
+
+        if( selector.length() > 0 && selector.charAt( 0 ) == '#' )
+        {
+            selector = selector.substring( 1 );
+
+            for( ServerComputer computer : computers )
+            {
+                String id = Integer.toString( computer.getID() );
+                if( id.startsWith( selector ) ) options.add( "#" + id );
+            }
+        }
+        else if( selector.length() > 0 && selector.charAt( 0 ) == '@' )
+        {
+            String label = selector.substring( 1 );
+            for( ServerComputer computer : computers )
+            {
+                String thisLabel = computer.getLabel();
+                if( thisLabel != null && thisLabel.startsWith( label ) ) options.add( "@" + thisLabel );
+            }
+        }
+        else if( selector.length() > 0 && selector.charAt( 0 ) == '~' )
+        {
+            String familyName = selector.substring( 1 ).toLowerCase( Locale.ENGLISH );
+            for( ComputerFamily family : ComputerFamily.values() )
+            {
+                if( family.name().toLowerCase( Locale.ENGLISH ).startsWith( familyName ) )
+                {
+                    options.add( "~" + family.name() );
+                }
+            }
+        }
+        else
+        {
+            for( ServerComputer computer : computers )
+            {
+                String id = Integer.toString( computer.getInstanceID() );
+                if( id.startsWith( selector ) ) options.add( id );
+            }
+        }
+
+        if( options.size() > 100 )
+        {
+            ArrayList<String> result = Lists.newArrayListWithCapacity( 100 );
+            for( String element : options )
+            {
+                if( result.size() > 100 ) break;
+                result.add( element );
+            }
+
+            return result;
+        }
+        else
+        {
+            return Lists.newArrayList( options );
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/command/ContainerViewComputer.java

@@ -0,0 +1,64 @@
+package dan200.computercraft.shared.command;
+
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.computer.core.ComputerFamily;
+import dan200.computercraft.shared.computer.core.IComputer;
+import dan200.computercraft.shared.computer.core.IContainerComputer;
+import dan200.computercraft.shared.computer.core.ServerComputer;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.inventory.Container;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.util.text.TextComponentTranslation;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class ContainerViewComputer extends Container implements IContainerComputer
+{
+    private final IComputer computer;
+
+    public ContainerViewComputer( IComputer computer )
+    {
+        this.computer = computer;
+    }
+
+    @Nullable
+    @Override
+    public IComputer getComputer()
+    {
+        return computer;
+    }
+
+    @Override
+    public boolean canInteractWith( @Nonnull EntityPlayer player )
+    {
+        if( computer instanceof ServerComputer )
+        {
+            ServerComputer serverComputer = (ServerComputer) computer;
+
+            // If this computer no longer exists then discard it.
+            if( ComputerCraft.serverComputerRegistry.get( serverComputer.getInstanceID() ) != serverComputer )
+            {
+                return false;
+            }
+
+            // If we're a command computer then ensure we're in creative
+            if( serverComputer.getFamily() == ComputerFamily.Command )
+            {
+                MinecraftServer server = player.getServer();
+                if( server == null || !server.isCommandBlockEnabled() )
+                {
+                    player.sendMessage( new TextComponentTranslation( "advMode.notEnabled" ) );
+                    return false;
+                }
+                else if( !ComputerCraft.canPlayerUseCommands( player ) || !player.capabilities.isCreativeMode )
+                {
+                    player.sendMessage( new TextComponentTranslation( "advMode.notAllowed" ) );
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/ChatHelpers.java

@@ -0,0 +1,117 @@
+package dan200.computercraft.shared.command.framework;
+
+import com.google.common.base.Strings;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.text.ITextComponent;
+import net.minecraft.util.text.Style;
+import net.minecraft.util.text.TextComponentString;
+import net.minecraft.util.text.TextFormatting;
+import net.minecraft.util.text.event.ClickEvent;
+import net.minecraft.util.text.event.HoverEvent;
+
+/**
+ * Various helpers for building chat messages
+ */
+public final class ChatHelpers
+{
+    private static final TextFormatting HEADER = TextFormatting.LIGHT_PURPLE;
+    private static final TextFormatting SYNOPSIS = TextFormatting.AQUA;
+    private static final TextFormatting NAME = TextFormatting.GREEN;
+
+    public static ITextComponent coloured( String text, TextFormatting colour )
+    {
+        ITextComponent component = new TextComponentString( text == null ? "" : text );
+        component.getStyle().setColor( colour );
+        return component;
+    }
+
+    public static ITextComponent text( String text )
+    {
+        return new TextComponentString( text == null ? "" : text );
+    }
+
+    public static ITextComponent list( ITextComponent... children )
+    {
+        ITextComponent component = new TextComponentString( "" );
+        for( ITextComponent child : children )
+        {
+            component.appendSibling( child );
+        }
+        return component;
+    }
+
+    public static ITextComponent getHelp( CommandContext context, ISubCommand command, String prefix )
+    {
+        ITextComponent output = new TextComponentString( "" )
+            .appendSibling( coloured( "/" + prefix + " " + command.getUsage( context ), HEADER ) )
+            .appendText( " " )
+            .appendSibling( coloured( command.getSynopsis(), SYNOPSIS ) );
+
+        String desc = command.getDescription();
+        if( !Strings.isNullOrEmpty( desc ) ) output.appendText( "\n" + desc );
+
+        if( command instanceof CommandRoot )
+        {
+            for( ISubCommand subCommand : ((CommandRoot) command).getSubCommands().values() )
+            {
+                if( !subCommand.checkPermission( context ) ) continue;
+
+                output.appendText( "\n" );
+
+                ITextComponent component = coloured( subCommand.getName(), NAME );
+                component.getStyle().setClickEvent( new ClickEvent(
+                    ClickEvent.Action.SUGGEST_COMMAND,
+                    "/" + prefix + " " + subCommand.getName()
+                ) );
+                output.appendSibling( component );
+
+                output.appendText( " - " + subCommand.getSynopsis() );
+            }
+        }
+
+        return output;
+    }
+
+    public static ITextComponent position( BlockPos pos )
+    {
+        if( pos == null ) return text( "<no pos>" );
+        return formatted( "%d, %d, %d", pos.getX(), pos.getY(), pos.getZ() );
+    }
+
+    public static ITextComponent bool( boolean value )
+    {
+        if( value )
+        {
+            ITextComponent component = new TextComponentString( "Y" );
+            component.getStyle().setColor( TextFormatting.GREEN );
+            return component;
+        }
+        else
+        {
+            ITextComponent component = new TextComponentString( "N" );
+            component.getStyle().setColor( TextFormatting.RED );
+            return component;
+        }
+    }
+
+    public static ITextComponent formatted( String format, Object... args )
+    {
+        return new TextComponentString( String.format( format, args ) );
+    }
+
+    public static ITextComponent link( ITextComponent component, String command, String toolTip )
+    {
+        Style style = component.getStyle();
+
+        if( style.getColor() == null ) style.setColor( TextFormatting.YELLOW );
+        style.setClickEvent( new ClickEvent( ClickEvent.Action.RUN_COMMAND, command ) );
+        style.setHoverEvent( new HoverEvent( HoverEvent.Action.SHOW_TEXT, new TextComponentString( toolTip ) ) );
+
+        return component;
+    }
+
+    public static ITextComponent header( String text )
+    {
+        return coloured( text, HEADER );
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/CommandContext.java

@@ -0,0 +1,100 @@
+package dan200.computercraft.shared.command.framework;
+
+import com.google.common.collect.Lists;
+import net.minecraft.command.ICommandSender;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.server.MinecraftServer;
+import net.minecraftforge.common.util.FakePlayer;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Represents the way a command was invoked, including the command sender, the current server and
+ * the "path" to this command.
+ */
+public final class CommandContext
+{
+    private final MinecraftServer server;
+    private final ICommandSender sender;
+    private final List<ISubCommand> path;
+
+    public CommandContext( MinecraftServer server, ICommandSender sender, ISubCommand initial )
+    {
+        this.server = server;
+        this.sender = sender;
+        this.path = Collections.singletonList( initial );
+    }
+
+    private CommandContext( MinecraftServer server, ICommandSender sender, List<ISubCommand> path )
+    {
+        this.server = server;
+        this.sender = sender;
+        this.path = path;
+    }
+
+    public CommandContext enter( ISubCommand child )
+    {
+        List<ISubCommand> newPath = Lists.newArrayListWithExpectedSize( path.size() + 1 );
+        newPath.addAll( path );
+        newPath.add( child );
+        return new CommandContext( server, sender, newPath );
+    }
+
+    public CommandContext parent()
+    {
+        if( path.size() == 1 ) throw new IllegalStateException( "No parent command" );
+        return new CommandContext( server, sender, path.subList( 0, path.size() - 1 ) );
+    }
+
+    public String getFullPath()
+    {
+        StringBuilder out = new StringBuilder();
+        boolean first = true;
+        for( ISubCommand command : path )
+        {
+            if( first )
+            {
+                first = false;
+            }
+            else
+            {
+                out.append( ' ' );
+            }
+
+            out.append( command.getName() );
+        }
+
+        return out.toString();
+    }
+
+    public String getFullUsage()
+    {
+        return "/" + getFullPath() + " " + path.get( path.size() - 1 ).getUsage( this );
+    }
+
+    public List<ISubCommand> getPath()
+    {
+        return Collections.unmodifiableList( path );
+    }
+
+    public String getRootCommand()
+    {
+        return path.get( 0 ).getName();
+    }
+
+    public MinecraftServer getServer()
+    {
+        return server;
+    }
+
+    public ICommandSender getSender()
+    {
+        return sender;
+    }
+
+    public boolean fromPlayer()
+    {
+        return sender instanceof EntityPlayerMP && !(sender instanceof FakePlayer);
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/CommandDelegate.java

@@ -0,0 +1,91 @@
+package dan200.computercraft.shared.command.framework;
+
+import dan200.computercraft.ComputerCraft;
+import net.minecraft.command.CommandException;
+import net.minecraft.command.ICommand;
+import net.minecraft.command.ICommandSender;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.util.math.BlockPos;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * {@link net.minecraft.command.ICommand} which delegates to a {@link ISubCommand}.
+ */
+public class CommandDelegate implements ICommand
+{
+    private final ISubCommand command;
+
+    public CommandDelegate( ISubCommand command )
+    {
+        this.command = command;
+    }
+
+    @Nonnull
+    @Override
+    public String getName()
+    {
+        return command.getName();
+    }
+
+    @Nonnull
+    @Override
+    public String getUsage( @Nonnull ICommandSender sender )
+    {
+        return new CommandContext( sender.getServer(), sender, command ).getFullUsage();
+    }
+
+    @Nonnull
+    @Override
+    public List<String> getAliases()
+    {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public void execute( @Nonnull MinecraftServer server, @Nonnull ICommandSender sender, @Nonnull String[] args ) throws CommandException
+    {
+        try
+        {
+            command.execute( new CommandContext( server, sender, command ), Arrays.asList( args ) );
+        }
+        catch( CommandException e )
+        {
+            throw e;
+        }
+        catch( Throwable e )
+        {
+            ComputerCraft.log.error( "Unhandled exception in command", e );
+            throw new CommandException( "Unhandled exception: " + e.toString() );
+        }
+    }
+
+    @Nonnull
+    @Override
+    public List<String> getTabCompletions( @Nonnull MinecraftServer server, @Nonnull ICommandSender sender, @Nonnull String[] args, @Nullable BlockPos pos )
+    {
+        return command.getCompletion( new CommandContext( server, sender, command ), Arrays.asList( args ) );
+    }
+
+    @Override
+    public boolean checkPermission( @Nonnull MinecraftServer server, @Nonnull ICommandSender sender )
+    {
+        return command.checkPermission( new CommandContext( server, sender, command ) );
+    }
+
+    @Override
+    public boolean isUsernameIndex( @Nonnull String[] args, int index )
+    {
+        return false;
+    }
+
+    @Override
+    public int compareTo( @Nonnull ICommand o )
+    {
+        return getName().compareTo( o.getName() );
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/CommandRoot.java

@@ -0,0 +1,149 @@
+package dan200.computercraft.shared.command.framework;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import net.minecraft.command.CommandBase;
+import net.minecraft.command.CommandException;
+
+import javax.annotation.Nonnull;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A command which delegates to a series of sub commands
+ */
+public class CommandRoot implements ISubCommand
+{
+    private final String name;
+    private final String synopsis;
+    private final String description;
+    private final Map<String, ISubCommand> subCommands = Maps.newHashMap();
+
+    public CommandRoot( String name, String synopsis, String description )
+    {
+        this.name = name;
+        this.synopsis = synopsis;
+        this.description = description;
+
+        register( new SubCommandHelp( this ) );
+    }
+
+    public void register( ISubCommand command )
+    {
+        subCommands.put( command.getName(), command );
+    }
+
+    @Nonnull
+    @Override
+    public String getName()
+    {
+        return name;
+    }
+
+    @Nonnull
+    @Override
+    public String getUsage( CommandContext context )
+    {
+        StringBuilder out = new StringBuilder( "<" );
+        boolean first = true;
+        for( ISubCommand command : subCommands.values() )
+        {
+            if( command.checkPermission( context ) )
+            {
+                if( first )
+                {
+                    first = false;
+                }
+                else
+                {
+                    out.append( "|" );
+                }
+
+                out.append( command.getName() );
+            }
+        }
+
+        return out.append( ">" ).toString();
+    }
+
+    @Nonnull
+    @Override
+    public String getSynopsis()
+    {
+        return synopsis;
+    }
+
+    @Nonnull
+    @Override
+    public String getDescription()
+    {
+        return description;
+    }
+
+    @Override
+    public boolean checkPermission( @Nonnull CommandContext context )
+    {
+        for( ISubCommand command : subCommands.values() )
+        {
+            if( !(command instanceof SubCommandHelp) && command.checkPermission( context ) ) return true;
+        }
+        return false;
+    }
+
+    public Map<String, ISubCommand> getSubCommands()
+    {
+        return Collections.unmodifiableMap( subCommands );
+    }
+
+    @Override
+    public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+    {
+        if( arguments.size() == 0 )
+        {
+            context.getSender().sendMessage( ChatHelpers.getHelp( context, this, context.getFullPath() ) );
+        }
+        else
+        {
+            ISubCommand command = subCommands.get( arguments.get( 0 ) );
+            if( command == null || !command.checkPermission( context ) )
+            {
+                throw new CommandException( context.getFullUsage() );
+            }
+
+            command.execute( context.enter( command ), arguments.subList( 1, arguments.size() ) );
+        }
+    }
+
+    @Nonnull
+    @Override
+    public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+    {
+        if( arguments.size() == 0 )
+        {
+            return Lists.newArrayList( subCommands.keySet() );
+        }
+        else if( arguments.size() == 1 )
+        {
+            List<String> list = Lists.newArrayList();
+            String match = arguments.get( 0 );
+
+            for( ISubCommand command : subCommands.values() )
+            {
+                if( CommandBase.doesStringStartWith( match, command.getName() ) && command.checkPermission( context ) )
+                {
+                    list.add( command.getName() );
+                }
+            }
+
+            return list;
+        }
+        else
+        {
+            ISubCommand command = subCommands.get( arguments.get( 0 ) );
+            if( command == null || !command.checkPermission( context ) ) return Collections.emptyList();
+
+            return command.getCompletion( context, arguments.subList( 1, arguments.size() ) );
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/ISubCommand.java

@@ -0,0 +1,80 @@
+package dan200.computercraft.shared.command.framework;
+
+import net.minecraft.command.CommandException;
+import net.minecraft.command.ICommand;
+import net.minecraft.command.ICommandSender;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.util.math.BlockPos;
+
+import javax.annotation.Nonnull;
+import java.util.List;
+
+/**
+ * A slightly different implementation of {@link ICommand} which is delegated to.
+ */
+public interface ISubCommand
+{
+    /**
+     * Get the name of this command
+     *
+     * @return The name of this command
+     * @see ICommand#getName()
+     */
+    @Nonnull
+    String getName();
+
+    /**
+     * Get the usage of this command
+     *
+     * @param context The context this command is executed in
+     * @return The usage of this command
+     * @see ICommand#getUsage(ICommandSender)
+     */
+    @Nonnull
+    String getUsage( CommandContext context );
+
+    /**
+     * Get a short description of this command, including its usage.
+     *
+     * @return The command's synopsis
+     */
+    @Nonnull
+    String getSynopsis();
+
+    /**
+     * Get the lengthy description of this command. This synopsis is prepended to this.
+     *
+     * @return The command's description
+     */
+    @Nonnull
+    String getDescription();
+
+    /**
+     * Determine whether a given command sender has permission to execute this command.
+     *
+     * @param context The current command context.
+     * @return Whether this command can be executed.
+     * @see ICommand#checkPermission(MinecraftServer, ICommandSender)
+     */
+    boolean checkPermission( @Nonnull CommandContext context );
+
+    /**
+     * Execute this command
+     *
+     * @param context   The current command context.
+     * @param arguments The arguments passed  @throws CommandException When an error occurs
+     * @see ICommand#execute(MinecraftServer, ICommandSender, String[])
+     */
+    void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException;
+
+    /**
+     * Get a list of possible completions
+     *
+     * @param context   The current command context.
+     * @param arguments The arguments passed. You should complete the last one.
+     * @return List of possible completions
+     * @see ICommand#getTabCompletions(MinecraftServer, ICommandSender, String[], BlockPos)
+     */
+    @Nonnull
+    List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments );
+}

src/main/java/dan200/computercraft/shared/command/framework/SubCommandBase.java

@@ -0,0 +1,69 @@
+package dan200.computercraft.shared.command.framework;
+
+import javax.annotation.Nonnull;
+import java.util.Collections;
+import java.util.List;
+
+public abstract class SubCommandBase implements ISubCommand
+{
+    private final String name;
+    private final String usage;
+    private final String synopsis;
+    private final String description;
+    private final UserLevel level;
+
+    public SubCommandBase( String name, String usage, String synopsis, UserLevel level, String description )
+    {
+        this.name = name;
+        this.usage = usage;
+        this.synopsis = synopsis;
+        this.description = description;
+        this.level = level;
+    }
+
+    public SubCommandBase( String name, String synopsis, UserLevel level, String description )
+    {
+        this( name, "", synopsis, level, description );
+    }
+
+    @Nonnull
+    @Override
+    public String getName()
+    {
+        return name;
+    }
+
+    @Nonnull
+    @Override
+    public String getUsage( CommandContext context )
+    {
+        return usage;
+    }
+
+    @Nonnull
+    @Override
+    public String getSynopsis()
+    {
+        return synopsis;
+    }
+
+    @Nonnull
+    @Override
+    public String getDescription()
+    {
+        return description;
+    }
+
+    @Override
+    public boolean checkPermission( @Nonnull CommandContext context )
+    {
+        return level.canExecute( context );
+    }
+
+    @Nonnull
+    @Override
+    public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+    {
+        return Collections.emptyList();
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/SubCommandHelp.java

@@ -0,0 +1,127 @@
+package dan200.computercraft.shared.command.framework;
+
+import com.google.common.collect.Lists;
+import joptsimple.internal.Strings;
+import net.minecraft.command.CommandBase;
+import net.minecraft.command.CommandException;
+
+import javax.annotation.Nonnull;
+import java.util.Collections;
+import java.util.List;
+
+public class SubCommandHelp implements ISubCommand
+{
+    private final CommandRoot branchCommand;
+
+    public SubCommandHelp( CommandRoot branchCommand )
+    {
+        this.branchCommand = branchCommand;
+    }
+
+    @Nonnull
+    @Override
+    public String getName()
+    {
+        return "help";
+    }
+
+    @Nonnull
+    @Override
+    public String getUsage( CommandContext context )
+    {
+        return "[command]";
+    }
+
+    @Nonnull
+    @Override
+    public String getSynopsis()
+    {
+        return "Provide help for a specific command";
+    }
+
+    @Nonnull
+    @Override
+    public String getDescription()
+    {
+        return "";
+    }
+
+    @Override
+    public boolean checkPermission( @Nonnull CommandContext context )
+    {
+        return true;
+    }
+
+    @Override
+    public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+    {
+        ISubCommand command = branchCommand;
+
+        for( int i = 0; i < arguments.size(); i++ )
+        {
+            String commandName = arguments.get( i );
+            if( command instanceof CommandRoot )
+            {
+                command = ((CommandRoot) command).getSubCommands().get( commandName );
+            }
+            else
+            {
+                throw new CommandException( Strings.join( arguments.subList( 0, i ), " " ) + " has no sub-commands" );
+            }
+
+            if( command == null )
+            {
+                throw new CommandException( "No such command " + Strings.join( arguments.subList( 0, i + 1 ), "  " ) );
+            }
+        }
+
+        StringBuilder prefix = new StringBuilder( context.parent().getFullPath() );
+        for( String argument : arguments )
+        {
+            prefix.append( ' ' ).append( argument );
+        }
+        context.getSender().sendMessage( ChatHelpers.getHelp( context, command, prefix.toString() ) );
+    }
+
+    @Nonnull
+    @Override
+    public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+    {
+        CommandRoot command = branchCommand;
+
+        for( int i = 0; i < arguments.size() - 1; i++ )
+        {
+            String commandName = arguments.get( i );
+            ISubCommand subCommand = command.getSubCommands().get( commandName );
+
+            if( subCommand instanceof CommandRoot )
+            {
+                command = (CommandRoot) subCommand;
+            }
+            else
+            {
+                return Collections.emptyList();
+            }
+        }
+
+        if( arguments.size() == 0 )
+        {
+            return Lists.newArrayList( command.getSubCommands().keySet() );
+        }
+        else
+        {
+            List<String> list = Lists.newArrayList();
+            String match = arguments.get( arguments.size() - 1 );
+
+            for( String entry : command.getSubCommands().keySet() )
+            {
+                if( CommandBase.doesStringStartWith( match, entry ) )
+                {
+                    list.add( entry );
+                }
+            }
+
+            return list;
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/TextFormatter.java

@@ -0,0 +1,147 @@
+package dan200.computercraft.shared.command.framework;
+
+import net.minecraft.command.ICommandSender;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.util.text.ITextComponent;
+import net.minecraft.util.text.TextComponentString;
+import net.minecraft.util.text.TextFormatting;
+import net.minecraftforge.common.util.FakePlayer;
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.Arrays;
+
+import static dan200.computercraft.shared.command.framework.ChatHelpers.coloured;
+
+/**
+ * Adapated from Sponge's PaginationCalculator
+ */
+public class TextFormatter
+{
+    private static final char PADDING_CHAR = '\u02cc';
+
+    /**
+     * Yoinked from FontRenderer
+     *
+     * @see net.minecraft.client.gui.FontRenderer#charWidth
+     * @see net.minecraft.client.gui.FontRenderer#getCharWidth(char)
+     */
+    private static final String CHARACTERS = "\u00c0\u00c1\u00c2\u00c8\u00ca\u00cb\u00cd\u00d3\u00d4\u00d5\u00da\u00df\u00e3\u00f5\u011f\u0130\u0131\u0152\u0153\u015e\u015f\u0174\u0175\u017e\u0207\u0000\u0000\u0000\u0000\u0000\u0000\u0000 !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\u0000\u00c7\u00fc\u00e9\u00e2\u00e4\u00e0\u00e5\u00e7\u00ea\u00eb\u00e8\u00ef\u00ee\u00ec\u00c4\u00c5\u00c9\u00e6\u00c6\u00f4\u00f6\u00f2\u00fb\u00f9\u00ff\u00d6\u00dc\u00f8\u00a3\u00d8\u00d7\u0192\u00e1\u00ed\u00f3\u00fa\u00f1\u00d1\u00aa\u00ba\u00bf\u00ae\u00ac\u00bd\u00bc\u00a1\u00ab\u00bb\u2591\u2592\u2593\u2502\u2524\u2561\u2562\u2556\u2555\u2563\u2551\u2557\u255d\u255c\u255b\u2510\u2514\u2534\u252c\u251c\u2500\u253c\u255e\u255f\u255a\u2554\u2569\u2566\u2560\u2550\u256c\u2567\u2568\u2564\u2565\u2559\u2558\u2552\u2553\u256b\u256a\u2518\u250c\u2588\u2584\u258c\u2590\u2580\u03b1\u03b2\u0393\u03c0\u03a3\u03c3\u03bc\u03c4\u03a6\u0398\u03a9\u03b4\u221e\u2205\u2208\u2229\u2261\u00b1\u2265\u2264\u2320\u2321\u00f7\u2248\u00b0\u2219\u00b7\u221a\u207f\u00b2\u25a0\u0000";
+    private static final int[] CHAR_WIDTHS = new int[]{
+        6, 6, 6, 6, 6, 6, 4, 6, 6, 6, 6, 6, 6, 6, 6, 4,
+        4, 6, 7, 6, 6, 6, 6, 6, 6, 1, 1, 1, 1, 1, 1, 1,
+        1, 2, 5, 6, 6, 6, 6, 3, 5, 5, 5, 6, 2, 6, 2, 6,
+        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 2, 2, 5, 6, 5, 6,
+        7, 6, 6, 6, 6, 6, 6, 6, 6, 4, 6, 6, 6, 6, 6, 6,
+        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 4, 6, 4, 6, 6,
+        3, 6, 6, 6, 6, 6, 5, 6, 6, 2, 6, 5, 3, 6, 6, 6,
+        6, 6, 6, 6, 4, 6, 6, 6, 6, 6, 6, 5, 2, 5, 7, 6,
+        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 4, 6, 3, 6, 6,
+        6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 4, 6,
+        6, 3, 6, 6, 6, 6, 6, 6, 6, 7, 6, 6, 6, 2, 6, 6,
+        8, 9, 9, 6, 6, 6, 8, 8, 6, 8, 8, 8, 8, 8, 6, 6,
+        9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+        9, 9, 9, 9, 9, 9, 9, 9, 9, 6, 9, 9, 9, 5, 9, 9,
+        8, 7, 7, 8, 7, 8, 8, 8, 7, 8, 8, 7, 9, 9, 6, 7,
+        7, 7, 7, 7, 9, 6, 7, 8, 7, 6, 6, 9, 7, 6, 7, 1
+    };
+
+    private static final int[] EXTRA_CHARS = new int[]{
+        '\u20e2', '\u261b',
+    };
+
+    private static final byte[] EXTRA_WIDTHS = new byte[]{
+        8, 4,
+    };
+
+    public static int getWidth( int codePoint )
+    {
+        // Escape codes
+        if( codePoint == 167 ) return -1;
+
+        // Space and non-breaking space
+        if( codePoint == 32 || codePoint == 160 ) return 4;
+
+        // Built-in characters
+        int nonUnicodeIdx = CHARACTERS.indexOf( codePoint );
+        if( codePoint > 0 && nonUnicodeIdx != -1 ) return CHAR_WIDTHS[nonUnicodeIdx];
+
+        // Other special characters we use.
+        int extraIdx = Arrays.binarySearch( EXTRA_CHARS, codePoint );
+        if( extraIdx >= 0 ) return EXTRA_WIDTHS[extraIdx];
+
+        return 0;
+    }
+
+    public static int getWidth( ITextComponent component )
+    {
+        int total = 0;
+        if( component instanceof TextComponentString )
+        {
+            String contents = component.getUnformattedComponentText();
+
+            int bold = component.getStyle().getBold() ? 1 : 0;
+            for( int i = 0; i < contents.length(); i++ )
+            {
+                int cp = contents.charAt( i );
+                assert cp != '\n';
+                int width = getWidth( cp );
+                if( width < 0 )
+                {
+                    i++;
+                }
+                else
+                {
+                    total += width + bold;
+                }
+            }
+        }
+
+        for( ITextComponent child : component.getSiblings() )
+        {
+            total += getWidth( child );
+        }
+
+        return total;
+    }
+
+    public static boolean isPlayer( ICommandSender sender )
+    {
+        return sender instanceof EntityPlayerMP && !(sender instanceof FakePlayer);
+    }
+
+    public static int getMaxWidth( ICommandSender sender )
+    {
+        return isPlayer( sender ) ? 320 : 80;
+    }
+
+    public static int getWidthFor( ITextComponent component, ICommandSender sender )
+    {
+        return isPlayer( sender ) ? getWidth( component ) : component.getUnformattedText().length();
+    }
+
+    public static int getWidthFor( int codepoint, ICommandSender sender )
+    {
+        return isPlayer( sender ) ? getWidth( codepoint ) : 1;
+    }
+
+    public static void appendFixedWidth( ITextComponent out, ICommandSender sender, ITextComponent entry, int maxWidth )
+    {
+        out.appendSibling( entry );
+
+        int width = getWidthFor( entry, sender );
+        int delta = maxWidth - width;
+
+        int spaceWidth = getWidthFor( ' ', sender );
+        int spaces = delta / spaceWidth;
+        int extra = delta % spaces;
+
+        // Append a fixed number of spaces
+        if( spaces > 0 ) out.appendSibling( new TextComponentString( StringUtils.repeat( ' ', spaces ) ) );
+
+        // Append several minor characters to pad to a full string 
+        if( extra > 0 )
+        {
+            out.appendSibling( coloured( StringUtils.repeat( PADDING_CHAR, extra ), TextFormatting.GRAY ) );
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/TextTable.java

@@ -0,0 +1,170 @@
+package dan200.computercraft.shared.command.framework;
+
+import com.google.common.collect.Lists;
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.network.ComputerCraftPacket;
+import net.minecraft.command.ICommandSender;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.util.text.ITextComponent;
+import net.minecraft.util.text.TextComponentString;
+import net.minecraft.util.text.TextFormatting;
+import org.apache.commons.lang3.StringUtils;
+
+import javax.annotation.Nonnull;
+import java.util.ArrayList;
+import java.util.List;
+
+import static dan200.computercraft.shared.command.framework.ChatHelpers.coloured;
+import static dan200.computercraft.shared.command.framework.ChatHelpers.text;
+import static dan200.computercraft.shared.command.framework.TextFormatter.*;
+
+public class TextTable
+{
+    private static final ITextComponent SEPARATOR = coloured( "| ", TextFormatting.GRAY );
+    private static final ITextComponent LINE = text( "\n" );
+
+    private final int id;
+    private int columns = -1;
+    private final ITextComponent[] header;
+    private final List<ITextComponent[]> rows = Lists.newArrayList();
+
+    public TextTable( int id, @Nonnull ITextComponent... header )
+    {
+        this.id = id;
+        this.header = header;
+        this.columns = header.length;
+    }
+
+    public TextTable( int id )
+    {
+        this.id = id;
+        this.header = null;
+    }
+
+    public TextTable( int id, @Nonnull String... header )
+    {
+        this.id = id;
+        this.header = new ITextComponent[header.length];
+        for( int i = 0; i < header.length; i++ )
+        {
+            this.header[i] = ChatHelpers.header( header[i] );
+        }
+        this.columns = header.length;
+    }
+
+    public void addRow( @Nonnull ITextComponent... row )
+    {
+        if( columns == -1 )
+        {
+            columns = row.length;
+        }
+        else if( row.length != columns )
+        {
+            throw new IllegalArgumentException( "Row is the incorrect length" );
+        }
+
+        rows.add( row );
+    }
+
+    public void displayTo( ICommandSender sender )
+    {
+        if( columns <= 0 ) return;
+
+        int[] maxWidths = new int[columns];
+
+        if( header != null )
+        {
+            for( int i = 0; i < columns; i++ )
+            {
+                maxWidths[i] = getWidthFor( header[i], sender );
+            }
+        }
+
+        // Limit the number of rows to fit within a single chat window on default Minecraft
+        // options.
+        int height = isPlayer( sender ) ? 18 : 100;
+        int limit = rows.size() <= height ? rows.size() : height - 1;
+
+        for( int y = 0; y < limit; y++ )
+        {
+            ITextComponent[] row = rows.get( y );
+            for( int i = 0; i < row.length; i++ )
+            {
+                int width = getWidthFor( row[i], sender );
+                if( width > maxWidths[i] ) maxWidths[i] = width;
+            }
+        }
+
+        // Add a small amount of extra padding. This defaults to 3 spaces for players
+        // and 1 for everyone else.
+        int padding = isPlayer( sender ) ? getWidth( ' ' ) * 3 : 1;
+        for( int i = 0; i < maxWidths.length; i++ ) maxWidths[i] += padding;
+
+        int totalWidth = (columns - 1) * getWidthFor( SEPARATOR, sender );
+        for( int x : maxWidths ) totalWidth += x;
+
+        // TODO: Limit the widths of some entries if totalWidth > maxWidth
+
+        List<ITextComponent> out = new ArrayList<>();
+
+        if( header != null )
+        {
+            TextComponentString line = new TextComponentString( "" );
+            for( int i = 0; i < columns - 1; i++ )
+            {
+                appendFixedWidth( line, sender, header[i], maxWidths[i] );
+                line.appendSibling( SEPARATOR );
+            }
+            line.appendSibling( header[columns - 1] );
+            out.add( line );
+
+            // Round the width up rather than down
+            int rowCharWidth = getWidthFor( '=', sender );
+            int rowWidth = totalWidth / rowCharWidth + (totalWidth % rowCharWidth == 0 ? 0 : 1);
+            out.add( coloured( StringUtils.repeat( '=', rowWidth ), TextFormatting.GRAY ) );
+        }
+
+        for( int i = 0; i < limit; i++ )
+        {
+            TextComponentString line = new TextComponentString( "" );
+            ITextComponent[] row = rows.get( i );
+            for( int j = 0; j < columns - 1; j++ )
+            {
+                appendFixedWidth( line, sender, row[j], maxWidths[j] );
+                line.appendSibling( SEPARATOR );
+            }
+            line.appendSibling( row[columns - 1] );
+            out.add( line );
+        }
+
+        if( rows.size() > limit )
+        {
+            out.add( coloured( (rows.size() - limit) + " additional rows...", TextFormatting.AQUA ) );
+        }
+
+        if( isPlayer( sender ) && id != 0 )
+        {
+            ComputerCraftPacket packet = new ComputerCraftPacket();
+            packet.m_packetType = ComputerCraftPacket.PostChat;
+            packet.m_dataInt = new int[]{ id };
+
+            String[] lines = packet.m_dataString = new String[out.size()];
+            for( int i = 0; i < out.size(); i++ )
+            {
+                lines[i] = ITextComponent.Serializer.componentToJson( out.get( i ) );
+            }
+
+            ComputerCraft.sendToPlayer( (EntityPlayerMP) sender, packet );
+        }
+        else
+        {
+            ITextComponent result = new TextComponentString( "" );
+            for( int i = 0; i < out.size(); i++ )
+            {
+                if( i > 0 ) result.appendSibling( LINE );
+                result.appendSibling( out.get( i ) );
+            }
+            sender.sendMessage( result );
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/command/framework/UserLevel.java

@@ -0,0 +1,63 @@
+package dan200.computercraft.shared.command.framework;
+
+import net.minecraft.command.ICommandSender;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.server.MinecraftServer;
+
+/**
+ * The level a user must be at in order to execute a command.
+ */
+public enum UserLevel
+{
+    /**
+     * Only can be used by the owner of the server: namely the server console or the player in SSP.
+     */
+    OWNER,
+
+    /**
+     * Can only be used by ops.
+     */
+    OP,
+
+    /**
+     * Can be used by any op, or the player in SSP.
+     */
+    OWNER_OP,
+
+    /**
+     * Can be used by anyone.
+     */
+    ANYONE;
+
+    public int toLevel()
+    {
+        switch( this )
+        {
+            case OWNER:
+                return 4;
+            case OP:
+            case OWNER_OP:
+                return 2;
+            case ANYONE:
+            default:
+                return 0;
+        }
+    }
+
+    public boolean canExecute( CommandContext context )
+    {
+        if( this == ANYONE ) return true;
+
+        // We *always* allow level 0 stuff, even if the
+        MinecraftServer server = context.getServer();
+        ICommandSender sender = context.getSender();
+
+        if( server.isSinglePlayer() && sender instanceof EntityPlayerMP &&
+            ((EntityPlayerMP) sender).getGameProfile().getName().equalsIgnoreCase( server.getServerOwner() ) )
+        {
+            if( this == OWNER || this == OWNER_OP ) return true;
+        }
+
+        return sender.canUseCommand( toLevel(), context.getRootCommand() );
+    }
+}

src/main/java/dan200/computercraft/shared/common/BlockGeneric.java

@@ -36,7 +36,7 @@ public abstract class BlockGeneric extends Block implements
     protected BlockGeneric( Material material )
     {
         super( material );
-        this.isBlockContainer = true;
+        this.hasTileEntity = true;
     }
 
     protected abstract IBlockState getDefaultBlockState( int damage, EnumFacing placedSide );

src/main/java/dan200/computercraft/shared/common/ClientTerminal.java

@@ -14,29 +14,28 @@ public class ClientTerminal implements ITerminal
     private boolean m_colour;
     private Terminal m_terminal;
     private boolean m_terminalChanged;
-    private boolean m_terminalChangedLastFrame;
 
     public ClientTerminal( boolean colour )
     {
         m_colour = colour;
         m_terminal = null;
         m_terminalChanged = false;
-        m_terminalChangedLastFrame = false;
     }
 
     public void update()
     {
-        m_terminalChangedLastFrame = m_terminalChanged || (m_terminal != null && m_terminal.getChanged());
         if( m_terminal != null )
         {
+            m_terminalChanged |= m_terminal.getChanged();
             m_terminal.clearChanged();
         }
-        m_terminalChanged = false;
     }
 
-    public boolean hasTerminalChanged()
+    public boolean pollTerminalChanged()
     {
-        return m_terminalChangedLastFrame;
+        boolean changed = m_terminalChanged;
+        m_terminalChanged = false;
+        return changed;
     }
 
     // ITerminal implementation

src/main/java/dan200/computercraft/shared/common/ColourableRecipe.java

@@ -86,7 +86,7 @@ public class ColourableRecipe extends IForgeRegistryEntry.Impl<IRecipe> implemen
     }
 
     @Override
-    public boolean isHidden()
+    public boolean isDynamic()
     {
         return true;
     }

src/main/java/dan200/computercraft/shared/common/ServerTerminal.java

@@ -54,6 +54,11 @@ public class ServerTerminal implements ITerminal
         }
     }
 
+    protected void markTerminalChanged()
+    {
+        m_terminalChanged = true;
+    }
+
     public void update()
     {
         m_terminalChangedLastFrame = m_terminalChanged || (m_terminal != null && m_terminal.getChanged());

src/main/java/dan200/computercraft/shared/computer/blocks/BlockCommandComputer.java

@@ -42,7 +42,7 @@ public class BlockCommandComputer extends BlockComputerBase
         super( Material.IRON );
         setBlockUnbreakable();
         setResistance( 6000000.0F );
-        setUnlocalizedName( "computercraft:command_computer" );
+        setTranslationKey( "computercraft:command_computer" );
         setCreativeTab( ComputerCraft.mainCreativeTab );
         setDefaultState( this.blockState.getBaseState()
             .withProperty( Properties.FACING, EnumFacing.NORTH )
@@ -62,7 +62,7 @@ public class BlockCommandComputer extends BlockComputerBase
     @Deprecated
     public IBlockState getStateFromMeta( int meta )
     {
-        EnumFacing dir = EnumFacing.getFront( meta & 0x7 );
+        EnumFacing dir = EnumFacing.byIndex( meta & 0x7 );
         if( dir.getAxis() == EnumFacing.Axis.Y )
         {
             dir = EnumFacing.NORTH;

src/main/java/dan200/computercraft/shared/computer/blocks/BlockComputer.java

@@ -44,7 +44,7 @@ public class BlockComputer extends BlockComputerBase
     {
         super( Material.ROCK );
         setHardness( 2.0f );
-        setUnlocalizedName( "computercraft:computer" );
+        setTranslationKey( "computercraft:computer" );
         setCreativeTab( ComputerCraft.mainCreativeTab );
         setDefaultState( this.blockState.getBaseState()
             .withProperty( Properties.FACING, EnumFacing.NORTH )
@@ -65,7 +65,7 @@ public class BlockComputer extends BlockComputerBase
     @Deprecated
     public IBlockState getStateFromMeta( int meta )
     {
-        EnumFacing dir = EnumFacing.getFront( meta & 0x7 );
+        EnumFacing dir = EnumFacing.byIndex( meta & 0x7 );
         if( dir.getAxis() == EnumFacing.Axis.Y )
         {
             dir = EnumFacing.NORTH;

src/main/java/dan200/computercraft/shared/computer/blocks/ComputerPeripheral.java

@@ -97,4 +97,11 @@ public class ComputerPeripheral
     {
         return (other != null && other.getClass() == this.getClass());
     }
+
+    @Nonnull
+    @Override
+    public Object getTarget()
+    {
+        return m_computer.getTile();
+    }
 }