Don't run CI on 1.12

Our cable has a rather complex getCollisionBoundingBox implementation,
which (combined with computing the actual block state) ends up taking an
awful lot of time.

This shaves 9% off each frame. I don't miss 1.12 one bit.

.github/workflows/main-ci.yml

@@ -1,50 +0,0 @@
-name: Build
-
-on: [push, pull_request]
-
-jobs:
-  build:
-    name: Build
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v1
-
-    - name: Set up JDK 1.8
-      uses: actions/setup-java@v1
-      with:
-        java-version: 1.8
-
-    - name: Cache gradle dependencies
-      uses: actions/cache@v1
-      with:
-        path: ~/.gradle/caches
-        key: ${{ runner.os }}-gradle-${{ hashFiles('gradle.properties') }}
-        restore-keys: |
-          ${{ runner.os }}-gradle-
-
-    - name: Build with Gradle
-      run: ./gradlew build --no-daemon
-
-    - name: Upload Jar
-      uses: actions/upload-artifact@v1
-      with:
-        name: CC-Tweaked
-        path: build/libs
-
-  lint-lua:
-    name: Lint Lua
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v1
-
-    - name: Lint Lua code
-      run: |
-        test -d bin || mkdir bin
-        test -f bin/illuaminate || wget -q -Obin/illuaminate https://squiddev.cc/illuaminate/linux-x86-64/illuaminate
-        chmod +x bin/illuaminate
-        bin/illuaminate lint
-
-    - name: Check whitespace
-      run: python3 tools/check-lines.py

.github/workflows/make-doc.sh

@@ -1,16 +0,0 @@
-#!/usr/bin/env bash
-
-set -eu
-
-DEST="${GITHUB_REF#refs/*/}"
-echo "Uploading docs to https://tweaked.cc/$DEST"
-
-# Setup ssh key
-mkdir -p "$HOME/.ssh/"
-echo "$SSH_KEY" > "$HOME/.ssh/key"
-chmod 600 "$HOME/.ssh/key"
-
-# And upload
-rsync -avc -e "ssh -i $HOME/.ssh/key -o StrictHostKeyChecking=no -p $SSH_PORT" \
-      "$GITHUB_WORKSPACE/doc/" \
-      "$SSH_USER@$SSH_HOST:/var/www/tweaked.cc/$DEST"

.github/workflows/make-doc.yml

@@ -1,29 +0,0 @@
-name: Build documentation
-
-on:
-  push:
-    branches: [ master ]
-    tags:
-
-jobs:
-  make_doc:
-    name: Build
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v1
-
-    - name: Build documentation
-      run: |
-        test -d bin || mkdir bin
-        test -f bin/illuaminate || wget -q -Obin/illuaminate https://squiddev.cc/illuaminate/linux-x86-64/illuaminate
-        chmod +x bin/illuaminate
-        bin/illuaminate doc-gen
-
-    - name: Upload documentation
-      run: .github/workflows/make-doc.sh 2> /dev/null
-      env:
-        SSH_KEY:  ${{ secrets.SSH_KEY  }}
-        SSH_USER: ${{ secrets.SSH_USER }}
-        SSH_HOST: ${{ secrets.SSH_HOST }}
-        SSH_PORT: ${{ secrets.SSH_PORT }}

build.gradle

@@ -18,6 +18,7 @@ buildscript {
 
 plugins {
     id "checkstyle"
+    id "jacoco"
     id "com.github.hierynomus.license" version "0.15.0"
     id "com.matthewprenger.cursegradle" version "1.3.0"
     id "com.github.breadmoirai.github-release" version "2.2.4"
@@ -51,14 +52,6 @@ repositories {
         name "Charset"
         artifactPattern "https://asie.pl/files/mods/Charset/LibOnly/[module]-[revision](-[classifier]).[ext]"
     }
-    maven {
-        name "Amadornes"
-        url "https://maven.amadornes.com/"
-    }
-    maven {
-        name "CraftTweaker"
-        url "https://maven.blamejared.com/"
-    }
 }
 
 configurations {
@@ -77,7 +70,7 @@ dependencies {
 
     runtime "mezz.jei:jei_1.12.2:4.15.0.269"
 
-    shade 'org.squiddev:Cobalt:0.5.1-SNAPSHOT'
+    shade 'org.squiddev:Cobalt:0.5.5'
 
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.4.2'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.4.2'
@@ -143,6 +136,9 @@ task proguard(type: ProGuardTask, dependsOn: jar) {
     // We want to avoid as much obfuscation as possible. We're only doing this to shrink code size.
     dontobfuscate; dontoptimize; keepattributes; keepparameternames
 
+    // Tell ProGuard to shut up
+    dontwarn 'org.checkerframework.**'
+
     // Proguard will remove directories by default, but that breaks JarMount.
     keepdirectories 'assets/computercraft/lua**'
 
@@ -251,11 +247,20 @@ test {
     }
 }
 
+jacocoTestReport {
+    reports {
+        xml.enabled true
+        html.enabled true
+    }
+}
+
+check.dependsOn jacocoTestReport
+
 license {
     mapping("java", "SLASHSTAR_STYLE")
     strictCheck true
 
-    ext.year = Calendar.getInstance().get(Calendar.YEAR)
+    ext.year = 2020
 }
 
 [licenseMain, licenseFormatMain].forEach {

doc/stub/commands.lua

@@ -1,6 +1,77 @@
+--- Execute a specific command.
+--
+-- @tparam string command The command to execute.
+-- @treturn boolean Whether the command executed successfully.
+-- @treturn { string... } The output of this command, as a list of lines.
+-- @treturn number|nil The number of "affected" objects, or `nil` if the command
+-- failed. The definition of this varies from command to command.
+-- @usage Set the block above the command computer to stone.
+--
+--     commands.exec("setblock ~ ~1 ~ minecraft:stone")
 function exec(command) end
+
+--- Asynchronously execute a command.
+--
+-- Unlike @{exec}, this will immediately return, instead of waiting for the
+-- command to execute. This allows you to run multiple commands at the same
+-- time.
+--
+-- When this command has finished executing, it will queue a `task_complete`
+-- event containing the result of executing this command (what @{exec} would
+-- return).
+--
+-- @tparam string command The command to execute.
+-- @treturn number The "task id". When this command has been executed, it will
+-- queue a `task_complete` event with a matching id.
+-- @usage Asynchronously sets the block above the computer to stone.
+--
+--     commands.execAsync("~ ~1 ~ minecraft:stone")
+-- @see parallel One may also use the parallel API to run multiple commands at
+-- once.
 function execAsync(commad) end
+
+--- List all available commands which the computer has permission to execute.
+--
+-- @treturn { string... } A list of all available commands
 function list() end
+
+--- Get the position of the current command computer.
+--
+-- @treturn number This computer's x position.
+-- @treturn number This computer's y position.
+-- @treturn number This computer's z position.
+-- @see gps.locate To get the position of a non-command computer.
 function getBlockPosition() end
-function getBlockInfos(min_x, min_y, min_z, max_x, max_y, max_z) end
+
+--- Get some basic information about a block.
+--
+-- The returned table contains the current name, metadata and block state (as
+-- with @{turtle.inspect}). If there is a tile entity for that block, its NBT
+-- will also be returned.
+--
+-- @tparam number x The x position of the block to query.
+-- @tparam number y The y position of the block to query.
+-- @tparam number z The z position of the block to query.
+-- @treturn table The given block's information.
+-- @throws If the coordinates are not within the world, or are not currently
+-- loaded.
 function getBlockInfo(x, y, z) end
+
+--- Get information about a range of blocks.
+--
+-- This returns the same information as @{getBlockInfo}, just for multiple
+-- blocks at once.
+--
+-- Blocks are traversed by ascending y level, followed by z and x - the returned
+-- table may be indexed using `x + z*width + y*depth*depth`.
+--
+-- @tparam number min_x The start x coordinate of the range to query.
+-- @tparam number min_y The start y coordinate of the range to query.
+-- @tparam number min_z The start z coordinate of the range to query.
+-- @tparam number max_x The end x coordinate of the range to query.
+-- @tparam number max_y The end y coordinate of the range to query.
+-- @tparam number max_z The end z coordinate of the range to query.
+-- @treturn { table... } A list of information about each block.
+-- @throws If the coordinates are not within the world.
+-- @throws If trying to get information about more than 4096 blocks.
+function getBlockInfos(min_x, min_y, min_z, max_x, max_y, max_z) end

doc/stub/fs.lua

@@ -19,6 +19,48 @@ function getFreeSpace(path) end
 function find(pattern) end
 function getDir(path) end
 
+--- Returns true if a path is mounted to the parent filesystem.
+--
+-- The root filesystem "/" is considered a mount, along with disk folders and
+-- the rom folder. Other programs (such as network shares) can exstend this to
+-- make other mount types by correctly assigning their return value for getDrive.
+--
+-- @tparam string path The path to check.
+-- @treturn boolean If the path is mounted, rather than a normal file/folder.
+-- @throws If the path does not exist.
+-- @see getDrive
+function isDriveRoot(path) end
+
+--- Get the capacity of the drive at the given path.
+--
+-- This may be used in conjunction with @{getFreeSpace} to determine what
+-- percentage of this drive has been used.
+--
+-- @tparam string path The path of the drive to get.
+-- @treturn number This drive's capacity. This will be 0 for "read-only" drives,
+-- such as the ROM or treasure disks.
+function getCapacity(path) end
+
+--- Get attributes about a specific file or folder.
+--
+-- The returned attributes table contains information about the size of the
+-- file, whether it is a directory, and when it was created and last modified.
+--
+-- The creation and modification times are given as the number of milliseconds
+-- since the UNIX epoch. This may be given to @{os.date} in order to convert it
+-- to more usable form.
+--
+-- @tparam string path The path to get attributes for.
+-- @treturn { size = number, isDir = boolean, created = number, modified = number }
+-- The resulting attributes.
+-- @throws If the path does not exist.
+-- @see getSize If you only care about the file's size.
+-- @see isDir If you only care whether a path is a directory or not.
+function attributes(path) end
+
+-- Defined in bios.lua
+function complete(sPath, sLocation, bIncludeFiles, bIncludeDirs) end
+
 --- A file handle which can be read from.
 --
 -- @type ReadHandle

doc/stub/os.lua

@@ -15,3 +15,10 @@ function cancelTimer(id) end
 function cancelAlarm(id) end
 function epoch(timezone) end
 function date(format, time) end
+
+-- Defined in bios.lua
+function loadAPI(path) end
+function pullEvent(filter) end
+function pullEventRaw(filter) end
+function version() end
+function run(env, path, ...) end

doc/stub/pocket.lua

@@ -0,0 +1,28 @@
+--[[-
+Control the current pocket computer, adding or removing upgrades.
+
+This API is only available on pocket computers. As such, you may use its
+presence to determine what kind of computer you are using:
+
+```lua
+if pocket then
+  print("On a pocket computer")
+else
+  print("On something else")
+end
+```
+]]
+
+--- Search the player's inventory for another upgrade, replacing the existing
+-- one with that item if found.
+--
+-- This inventory search starts from the player's currently selected slot,
+-- allowing you to prioritise upgrades.
+--
+-- @throws If an upgrade cannot be found.
+function equipBack() end
+
+--- Remove the pocket computer's current upgrade.
+--
+-- @throws If this pocket computer does not currently have an upgrade.
+function unequipBack() end

doc/stub/redstone.lua

@@ -1,14 +1,120 @@
+--[[- Interact with redstone attached to this computer.
+
+The @{redstone} library exposes three "types" of redstone control:
+ - Binary input/output (@{setOutput}/@{getInput}): These simply check if a
+   redstone wire has any input or output. A signal strength of 1 and 15 are
+   treated the same.
+ - Analogue input/output (@{setAnalogueOutput}/@{getAnalogueInput}): These
+   work with the actual signal strength of the redstone wired, from 0 to 15.
+ - Bundled cables (@{setBundledOutput}/@{getBundledInput}): These interact with
+   "bundled" cables, such as those from Project:Red. These allow you to send
+   16 separate on/off signals. Each channel corresponds to a colour, with the
+   first being @{colors.white} and the last @{colors.black}.
+
+Whenever a redstone input changes, a `redstone` event will be fired. This may
+be used in or
+
+This module may also be referred to as `rs`. For example, one may call
+`rs.getSides()` instead of @{redstone.getSides}.
+
+@module redstone
+@usage Toggle the redstone signal above the computer every 0.5 seconds.
+
+    while true do
+        redstone.setOutput("top", not redstone.getOutput("top"))
+        sleep(0.5)
+    end
+@usage Mimic a redstone comparator in [subtraction mode][comparator].
+
+    while true do
+      local rear = rs.getAnalogueInput("back")
+      local sides = math.max(rs.getAnalogueInput("left"), rs.getAnalogueInput("right"))
+      rs.setAnalogueOutput("front", math.max(rear - sides, 0))
+
+      os.pullEvent("redstone") -- Wait for a change to inputs.
+    end
+
+[comparator]: https://minecraft.gamepedia.com/Redstone_Comparator#Subtract_signal_strength "Redstone Comparator on the Minecraft wiki."
+]]
+
+--- Returns a table containing the six sides of the computer. Namely, "top",
+-- "bottom", "left", "right", "front" and "back".
+--
+-- @treturn { string... } A table of valid sides.
 function getSides() end
+
+--- Turn the redstone signal of a specific side on or off.
+--
+-- @tparam string side The side to set.
+-- @tparam boolean on Whether the redstone signal should be on or off. When on,
+-- a signal strength of 15 is emitted.
 function setOutput(side, on) end
+
+--- Get the current redstone output of a specific side.
+--
+-- @tparam string side The side to get.
+-- @treturn boolean Whether the redstone output is on or off.
+-- @see setOutput
 function getOutput(side) end
+
+--- Get the current redstone input of a specific side.
+--
+-- @tparam string side The side to get.
+-- @treturn boolean Whether the redstone input is on or off.
 function getInput(side) end
-function setBundledOutput(side, output) end
-function getBundledOutput(side) end
-function getBundledInput(side) end
-function testBundledInput(side, mask) end
+
+--- Set the redstone signal strength for a specific side.
+--
+-- @tparam string side The side to set.
+-- @tparam number value The signal strength, between 0 and 15.
+-- @throws If `value` is not between 0 and 15.
 function setAnalogOutput(side, value) end
 setAnalogueOutput = setAnalogOutput
+
+--- Get the redstone output signal strength for a specific side.
+--
+-- @tparam string side The side to get.
+-- @treturn number The output signal strength, between 0 and 15.
+-- @see setAnalogueOutput
 function getAnalogOutput(sid) end
 getAnalogueOutput = getAnalogOutput
+
+--- Get the redstone input signal strength for a specific side.
+--
+-- @tparam string side The side to get.
+-- @treturn number The input signal strength, between 0 and 15.
 function getAnalogInput(side) end
-getAnalogueInput = getAnaloguInput
+getAnalogueInput = getAnalogInput
+
+--- Set the bundled cable output for a specific side.
+--
+-- @tparam string side The side to set.
+-- @tparam number The colour bitmask to set.
+-- @see colors.subtract For removing a colour from the bitmask.
+-- @see colors.combine For adding a colour to the bitmask.
+function setBundledOutput(side, output) end
+
+--- Get the bundled cable output for a specific side.
+--
+-- @tparam string side The side to get.
+-- @treturn number The bundled cable's output.
+function getBundledOutput(side) end
+
+--- Get the bundled cable input for a specific side.
+--
+-- @tparam string side The side to get.
+-- @treturn number The bundled cable's input.
+-- @see testBundledInput To determine if a specific colour is set.
+function getBundledInput(side) end
+
+--- Determine if a specific combination of colours are on for the given side.
+--
+-- @tparam string side The side to test.
+-- @tparam number mask The mask to test.
+-- @see getBundledInput
+-- @see colors.combine For adding a colour to the bitmask.
+-- @usage Check if @{colors.white} and @{colors.black} are on for above the
+-- computer.
+--
+--     print(redstone.testBundledInput("top", colors.combine(colors.white, colors.black)))
+function testBundledInput(side, mask) end

doc/stub/term.lua

@@ -15,14 +15,14 @@ isColor = isColour
 function getTextColour() end
 getTextColor = getTextColor
 function getBackgroundColour() end
-getBackgroundColour = getBackgroundColour
+getBackgroundColor = getBackgroundColour
 function blit(text, text_colours, background_colours) end
 function setPaletteColour(colour, ...) end
-setPaletteColour = setPaletteColour
+setPaletteColor = setPaletteColour
 function getPaletteColour(colour, ...) end
-getPaletteColour = getPaletteColour
+getPaletteColor = getPaletteColour
 function nativePaletteColour(colour) end
-nativePaletteColour = nativePaletteColour
+nativePaletteColor = nativePaletteColour
 
 --- @type Redirect
 local Redirect = {}

gradle.properties

@@ -1,5 +1,5 @@
 # Mod properties
-mod_version=1.87.0
+mod_version=1.89.2
 
 # Minecraft properties
 mc_version=1.12.2

illuaminate.sexp

@@ -33,17 +33,27 @@
 
     ;; It's useful to name arguments for documentation, so we allow this. It'd
     ;; be good to find a compromise in the future, but this works for now.
-    -var:unused-arg
+    -var:unused-arg)
 
-    ;; Some APIS (keys, colour and os mainly) are incomplete right now.
-    -var:unresolved-member)
   (lint
     (bracket-spaces
       (call no-space)
       (function-args no-space)
       (parens no-space)
       (table space)
-      (index no-space))))
+      (index no-space))
+
+    ;; colours imports from colors, and we don't handle that right now.
+    ;; keys is entirely dynamic, so we skip it.
+    (dynamic-modules colours keys)
+
+    (globals
+      :max
+      _CC_DEFAULT_SETTINGS
+      _CC_DISABLE_LUA51_FEATURES
+      ;; Ideally we'd pick these up from bios.lua, but illuaminate currently
+      ;; isn't smart enough.
+      sleep write printError read rs)))
 
 ;; We disable the unused global linter in bios.lua and the APIs. In the future
 ;; hopefully we'll get illuaminate to handle this.
@@ -60,17 +70,13 @@
 
 ;; Suppress warnings for currently undocumented modules.
 (at
-  (/doc/stub/commands.lua
-   /doc/stub/fs.lua
+  (/doc/stub/fs.lua
    /doc/stub/http.lua
    /doc/stub/os.lua
-   /doc/stub/redstone.lua
    /doc/stub/term.lua
    /doc/stub/turtle.lua
-   /src/main/resources/*/computercraft/lua/rom/apis/command/commands.lua
    /src/main/resources/*/computercraft/lua/rom/apis/io.lua
-   /src/main/resources/*/computercraft/lua/rom/apis/window.lua
-   /src/main/resources/*/computercraft/lua/rom/modules/main/cc/shell/completion.lua)
+   /src/main/resources/*/computercraft/lua/rom/apis/window.lua)
 
   (linters -doc:undocumented -doc:undocumented-arg))
 
@@ -79,6 +85,11 @@
   (/src/main/resources/*/computercraft/lua/rom/apis/textutils.lua
    /src/main/resources/*/computercraft/lua/rom/modules/main/cc/completion.lua
    /src/main/resources/*/computercraft/lua/rom/modules/main/cc/shell/completion.lua
-   /src/main/resources/*/computercraft/lua/rom/programs/advanced/multishell.lua
    /src/main/resources/*/computercraft/lua/rom/programs/shell.lua)
   (linters -doc:unresolved-reference))
+
+(at /src/test/resources/test-rom
+  (lint
+    (globals
+      :max sleep write
+      cct_test describe expect howlci fail it pending stub)))

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

@@ -112,7 +112,8 @@ public class ComputerCraft
     public static boolean disable_lua51_features = false;
     public static String default_computer_settings = "";
     public static boolean debug_enable = true;
-    public static boolean logPeripheralErrors = false;
+    public static boolean logPeripheralErrors = true;
+    public static boolean commandRequireCreative = true;
 
     public static int computer_threads = 1;
     public static long maxMainGlobalTime = TimeUnit.MILLISECONDS.toNanos( 10 );
@@ -137,6 +138,7 @@ public class ComputerCraft
     public static int modem_highAltitudeRangeDuringStorm = 384;
     public static int maxNotesPerTick = 8;
     public static MonitorRenderer monitorRenderer = MonitorRenderer.BEST;
+    public static long monitorBandwidth = 1_000_000;
 
     public static boolean turtlesNeedFuel = true;
     public static int turtleFuelLimit = 20000;
@@ -536,7 +538,7 @@ public class ComputerCraft
                     }
                     catch( IOException e )
                     {
-                        if( zipFile != null ) IoUtil.closeQuietly( zipFile );
+                        IoUtil.closeQuietly( zipFile );
                     }
                 }
             }

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

@@ -50,15 +50,14 @@ public final class FixedWidthFontRenderer
     {
     }
 
-    private static float toGreyscale( double[] rgb )
+    public static float toGreyscale( double[] rgb )
     {
         return (float) ((rgb[0] + rgb[1] + rgb[2]) / 3);
     }
 
-    private static int getColour( char c )
+    public static int getColour( char c, Colour def )
     {
-        int i = "0123456789abcdef".indexOf( c );
-        return i < 0 ? 0 : 15 - i;
+        return 15 - Terminal.getColour( c, def );
     }
 
     private static void drawChar( BufferBuilder buffer, float x, float y, int index, float r, float g, float b )
@@ -92,7 +91,7 @@ public final class FixedWidthFontRenderer
 
     private static void drawQuad( BufferBuilder buffer, float x, float y, float width, float height, Palette palette, boolean greyscale, char colourIndex )
     {
-        double[] colour = palette.getColour( getColour( colourIndex ) );
+        double[] colour = palette.getColour( getColour( colourIndex, Colour.Black ) );
         float r, g, b;
         if( greyscale )
         {
@@ -160,7 +159,7 @@ public final class FixedWidthFontRenderer
 
         for( int i = 0; i < text.length(); i++ )
         {
-            double[] colour = palette.getColour( getColour( textColour.charAt( i ) ) );
+            double[] colour = palette.getColour( getColour( textColour.charAt( i ), Colour.White ) );
             float r, g, b;
             if( greyscale )
             {

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

@@ -0,0 +1,158 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2020. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.client.render;
+
+import com.google.common.base.Strings;
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.client.gui.FixedWidthFontRenderer;
+import dan200.computercraft.shared.util.Palette;
+import net.minecraft.client.renderer.OpenGlHelper;
+import org.apache.commons.io.IOUtils;
+import org.lwjgl.BufferUtils;
+import org.lwjgl.opengl.GL13;
+import org.lwjgl.opengl.GL20;
+
+import java.io.BufferedInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.nio.FloatBuffer;
+
+class MonitorTextureBufferShader
+{
+    static final int TEXTURE_INDEX = GL13.GL_TEXTURE3;
+
+    private static final FloatBuffer PALETTE_BUFFER = BufferUtils.createFloatBuffer( 16 * 3 );
+
+    private static int uniformFont;
+    private static int uniformWidth;
+    private static int uniformHeight;
+    private static int uniformTbo;
+    private static int uniformPalette;
+
+    private static boolean initialised;
+    private static boolean ok;
+    private static int program;
+
+    static void setupUniform( int width, int height, Palette palette, boolean greyscale )
+    {
+        OpenGlHelper.glUniform1i( uniformWidth, width );
+        OpenGlHelper.glUniform1i( uniformHeight, height );
+
+        PALETTE_BUFFER.rewind();
+        for( int i = 0; i < 16; i++ )
+        {
+            double[] colour = palette.getColour( i );
+            if( greyscale )
+            {
+                float f = FixedWidthFontRenderer.toGreyscale( colour );
+                PALETTE_BUFFER.put( f ).put( f ).put( f );
+            }
+            else
+            {
+                PALETTE_BUFFER.put( (float) colour[0] ).put( (float) colour[1] ).put( (float) colour[2] );
+            }
+        }
+        PALETTE_BUFFER.flip();
+        OpenGlHelper.glUniform3( uniformPalette, PALETTE_BUFFER );
+    }
+
+    static boolean use()
+    {
+        if( initialised )
+        {
+            if( ok ) OpenGlHelper.glUseProgram( program );
+            return ok;
+        }
+
+        if( ok = load() )
+        {
+            GL20.glUseProgram( program );
+            OpenGlHelper.glUniform1i( uniformFont, 0 );
+            OpenGlHelper.glUniform1i( uniformTbo, TEXTURE_INDEX - GL13.GL_TEXTURE0 );
+        }
+
+        return ok;
+    }
+
+    private static boolean load()
+    {
+        initialised = true;
+
+        try
+        {
+            int vertexShader = loadShader( GL20.GL_VERTEX_SHADER, "assets/computercraft/shaders/monitor.vert" );
+            int fragmentShader = loadShader( GL20.GL_FRAGMENT_SHADER, "assets/computercraft/shaders/monitor.frag" );
+
+            program = OpenGlHelper.glCreateProgram();
+            OpenGlHelper.glAttachShader( program, vertexShader );
+            OpenGlHelper.glAttachShader( program, fragmentShader );
+            GL20.glBindAttribLocation( program, 0, "v_pos" );
+
+            OpenGlHelper.glLinkProgram( program );
+            boolean ok = OpenGlHelper.glGetProgrami( program, GL20.GL_LINK_STATUS ) != 0;
+            String log = OpenGlHelper.glGetProgramInfoLog( program, Short.MAX_VALUE ).trim();
+            if( !Strings.isNullOrEmpty( log ) )
+            {
+                ComputerCraft.log.warn( "Problems when linking monitor shader: {}", log );
+            }
+
+            GL20.glDetachShader( program, vertexShader );
+            GL20.glDetachShader( program, fragmentShader );
+            OpenGlHelper.glDeleteShader( vertexShader );
+            OpenGlHelper.glDeleteShader( fragmentShader );
+
+            if( !ok ) return false;
+
+            uniformFont = getUniformLocation( program, "u_font" );
+            uniformWidth = getUniformLocation( program, "u_width" );
+            uniformHeight = getUniformLocation( program, "u_height" );
+            uniformTbo = getUniformLocation( program, "u_tbo" );
+            uniformPalette = getUniformLocation( program, "u_palette" );
+
+            ComputerCraft.log.info( "Loaded monitor shader." );
+            return true;
+        }
+        catch( Exception e )
+        {
+            ComputerCraft.log.error( "Cannot load monitor shaders", e );
+            return false;
+        }
+    }
+
+    private static int loadShader( int kind, String path ) throws IOException
+    {
+        InputStream stream = TileEntityMonitorRenderer.class.getClassLoader().getResourceAsStream( path );
+        if( stream == null ) throw new IllegalArgumentException( "Cannot find " + path );
+        byte[] contents = IOUtils.toByteArray( new BufferedInputStream( stream ) );
+        ByteBuffer buffer = BufferUtils.createByteBuffer( contents.length );
+        buffer.put( contents );
+        buffer.position( 0 );
+
+        int shader = OpenGlHelper.glCreateShader( kind );
+
+        OpenGlHelper.glShaderSource( shader, buffer );
+        OpenGlHelper.glCompileShader( shader );
+
+        boolean ok = OpenGlHelper.glGetShaderi( shader, GL20.GL_COMPILE_STATUS ) != 0;
+        String log = OpenGlHelper.glGetShaderInfoLog( shader, Short.MAX_VALUE ).trim();
+        if( !Strings.isNullOrEmpty( log ) )
+        {
+            ComputerCraft.log.warn( "Problems when loading monitor shader {}: {}", path, log );
+        }
+
+        if( !ok ) throw new IllegalStateException( "Cannot compile shader " + path );
+        return shader;
+    }
+
+    private static int getUniformLocation( int program, String name )
+    {
+        int uniform = OpenGlHelper.glGetUniformLocation( program, name );
+        if( uniform == -1 ) throw new IllegalStateException( "Cannot find uniform " + name );
+        return uniform;
+    }
+}

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

@@ -8,28 +8,34 @@ package dan200.computercraft.client.render;
 import dan200.computercraft.client.FrameInfo;
 import dan200.computercraft.client.gui.FixedWidthFontRenderer;
 import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.core.terminal.TextBuffer;
 import dan200.computercraft.shared.peripheral.monitor.ClientMonitor;
 import dan200.computercraft.shared.peripheral.monitor.MonitorRenderer;
 import dan200.computercraft.shared.peripheral.monitor.TileMonitor;
+import dan200.computercraft.shared.util.Colour;
 import dan200.computercraft.shared.util.DirectionUtil;
 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.*;
 import net.minecraft.client.renderer.tileentity.TileEntitySpecialRenderer;
+import net.minecraft.client.renderer.vertex.DefaultVertexFormats;
 import net.minecraft.client.renderer.vertex.VertexBuffer;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.math.BlockPos;
 import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL13;
+import org.lwjgl.opengl.GL15;
+import org.lwjgl.opengl.GL31;
 
 import javax.annotation.Nonnull;
+import java.nio.ByteBuffer;
 
+import static dan200.computercraft.client.gui.FixedWidthFontRenderer.*;
 import static dan200.computercraft.shared.peripheral.monitor.TileMonitor.RENDER_MARGIN;
 
 public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMonitor>
 {
     private static final float MARGIN = (float) (TileMonitor.RENDER_MARGIN * 1.1);
+    private static ByteBuffer tboContents;
 
     @Override
     public void render( @Nonnull TileMonitor tileEntity, double posX, double posY, double posZ, float f, int i, float f2 )
@@ -97,8 +103,8 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
         if( terminal != null )
         {
             // Draw a terminal
-            double xScale = xSize / (terminal.getWidth() * FixedWidthFontRenderer.FONT_WIDTH);
-            double yScale = ySize / (terminal.getHeight() * FixedWidthFontRenderer.FONT_HEIGHT);
+            double xScale = xSize / (terminal.getWidth() * FONT_WIDTH);
+            double yScale = ySize / (terminal.getHeight() * FONT_HEIGHT);
 
             GlStateManager.pushMatrix();
             GlStateManager.scale( (float) xScale, (float) -yScale, 1.0f );
@@ -147,6 +153,59 @@ public class TileEntityMonitorRenderer extends TileEntitySpecialRenderer<TileMon
 
         switch( renderer )
         {
+            case TBO:
+            {
+                if( !MonitorTextureBufferShader.use() ) return;
+
+                Terminal terminal = monitor.getTerminal();
+                int width = terminal.getWidth(), height = terminal.getHeight();
+                int pixelWidth = width * FONT_WIDTH, pixelHeight = height * FONT_HEIGHT;
+
+                if( redraw )
+                {
+                    int size = width * height * 3;
+                    if( tboContents == null || tboContents.capacity() < size )
+                    {
+                        tboContents = GLAllocation.createDirectByteBuffer( size );
+                    }
+
+                    ByteBuffer monitorBuffer = tboContents;
+                    monitorBuffer.clear();
+                    for( int y = 0; y < height; y++ )
+                    {
+                        TextBuffer text = terminal.getLine( y ), textColour = terminal.getTextColourLine( y ), background = terminal.getBackgroundColourLine( y );
+                        for( int x = 0; x < width; x++ )
+                        {
+                            monitorBuffer.put( (byte) (text.charAt( x ) & 0xFF) );
+                            monitorBuffer.put( (byte) getColour( textColour.charAt( x ), Colour.White ) );
+                            monitorBuffer.put( (byte) getColour( background.charAt( x ), Colour.Black ) );
+                        }
+                    }
+                    monitorBuffer.flip();
+
+                    OpenGlHelper.glBindBuffer( GL31.GL_TEXTURE_BUFFER, monitor.tboBuffer );
+                    OpenGlHelper.glBufferData( GL31.GL_TEXTURE_BUFFER, monitorBuffer, GL15.GL_STATIC_DRAW );
+                    OpenGlHelper.glBindBuffer( GL31.GL_TEXTURE_BUFFER, 0 );
+                }
+
+                // Bind TBO texture and set up the uniforms. We've already set up the main font above.
+                GlStateManager.setActiveTexture( MonitorTextureBufferShader.TEXTURE_INDEX );
+                GL11.glBindTexture( GL31.GL_TEXTURE_BUFFER, monitor.tboTexture );
+                GlStateManager.setActiveTexture( GL13.GL_TEXTURE0 );
+
+                MonitorTextureBufferShader.setupUniform( width, height, terminal.getPalette(), !monitor.isColour() );
+
+                buffer.begin( GL11.GL_TRIANGLE_STRIP, DefaultVertexFormats.POSITION );
+                buffer.pos( -xMargin, -yMargin, 0 ).endVertex();
+                buffer.pos( -xMargin, pixelHeight + yMargin, 0 ).endVertex();
+                buffer.pos( pixelWidth + xMargin, -yMargin, 0 ).endVertex();
+                buffer.pos( pixelWidth + xMargin, pixelHeight + yMargin, 0 ).endVertex();
+                tessellator.draw();
+
+                OpenGlHelper.glUseProgram( 0 );
+                break;
+            }
+
             case VBO:
             {
                 VertexBuffer vbo = monitor.buffer;

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

@@ -16,11 +16,11 @@ import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class RedstoneAPI implements ILuaAPI
 {
-    private IAPIEnvironment m_environment;
+    private final IAPIEnvironment environment;
 
     public RedstoneAPI( IAPIEnvironment environment )
     {
-        m_environment = environment;
+        this.environment = environment;
     }
 
     @Override
@@ -63,31 +63,31 @@ public class RedstoneAPI implements ILuaAPI
                 // setOutput
                 ComputerSide side = parseSide( args );
                 boolean output = getBoolean( args, 1 );
-                m_environment.setOutput( side, output ? 15 : 0 );
+                environment.setOutput( side, output ? 15 : 0 );
                 return null;
             }
             case 2: // getOutput
-                return new Object[] { m_environment.getOutput( parseSide( args ) ) > 0 };
+                return new Object[] { environment.getOutput( parseSide( args ) ) > 0 };
             case 3: // getInput
-                return new Object[] { m_environment.getInput( parseSide( args ) ) > 0 };
+                return new Object[] { environment.getInput( parseSide( args ) ) > 0 };
             case 4:
             {
                 // setBundledOutput
                 ComputerSide side = parseSide( args );
                 int output = getInt( args, 1 );
-                m_environment.setBundledOutput( side, output );
+                environment.setBundledOutput( side, output );
                 return null;
             }
             case 5: // getBundledOutput
-                return new Object[] { m_environment.getBundledOutput( parseSide( args ) ) };
+                return new Object[] { environment.getBundledOutput( parseSide( args ) ) };
             case 6: // getBundledInput
-                return new Object[] { m_environment.getBundledInput( parseSide( args ) ) };
+                return new Object[] { environment.getBundledInput( parseSide( args ) ) };
             case 7:
             {
                 // testBundledInput
                 ComputerSide side = parseSide( args );
                 int mask = getInt( args, 1 );
-                int input = m_environment.getBundledInput( side );
+                int input = environment.getBundledInput( side );
                 return new Object[] { (input & mask) == mask };
             }
             case 8:
@@ -100,15 +100,15 @@ public class RedstoneAPI implements ILuaAPI
                 {
                     throw new LuaException( "Expected number in range 0-15" );
                 }
-                m_environment.setOutput( side, output );
+                environment.setOutput( side, output );
                 return null;
             }
             case 10:
             case 11: // getAnalogOutput/getAnalogueOutput
-                return new Object[] { m_environment.getOutput( parseSide( args ) ) };
+                return new Object[] { environment.getOutput( parseSide( args ) ) };
             case 12:
             case 13: // getAnalogInput/getAnalogueInput
-                return new Object[] { m_environment.getInput( parseSide( args ) ) };
+                return new Object[] { environment.getInput( parseSide( args ) ) };
             default:
                 return null;
         }

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

@@ -37,12 +37,8 @@ public abstract class HandleGeneric implements ILuaObject
     {
         m_open = false;
 
-        Closeable closeable = m_closable;
-        if( closeable != null )
-        {
-            IoUtil.closeQuietly( closeable );
-            m_closable = null;
-        }
+        IoUtil.closeQuietly( m_closable );
+        m_closable = null;
     }
 
     /**

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

@@ -106,7 +106,7 @@ public abstract class Resource<T extends Resource<T>> implements Closeable
 
     protected static <T extends Closeable> T closeCloseable( T closeable )
     {
-        if( closeable != null ) IoUtil.closeQuietly( closeable );
+        IoUtil.closeQuietly( closeable );
         return null;
     }
 

src/main/java/dan200/computercraft/core/apis/http/websocket/Websocket.java

@@ -221,7 +221,7 @@ public class Websocket extends Resource<Websocket>
 
         WeakReference<WebsocketHandle> websocketHandleRef = websocketHandle;
         WebsocketHandle websocketHandle = websocketHandleRef == null ? null : websocketHandleRef.get();
-        if( websocketHandle != null ) IoUtil.closeQuietly( websocketHandle );
+        IoUtil.closeQuietly( websocketHandle );
         this.websocketHandle = null;
     }
 

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

@@ -13,6 +13,7 @@ import javax.annotation.Nullable;
 import java.util.TreeSet;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.LockSupport;
@@ -49,11 +50,11 @@ import static dan200.computercraft.core.computer.TimeoutState.TIMEOUT;
 public final class ComputerThread
 {
     /**
-     * How often the computer thread monitor should run, in milliseconds.
+     * How often the computer thread monitor should run.
      *
      * @see Monitor
      */
-    private static final int MONITOR_WAKEUP = 100;
+    private static final long MONITOR_WAKEUP = TimeUnit.MILLISECONDS.toNanos( 100 );
 
     /**
      * The target latency between executing two tasks on a single machine.
@@ -76,6 +77,13 @@ public final class ComputerThread
      */
     private static final long LATENCY_MAX_TASKS = DEFAULT_LATENCY / DEFAULT_MIN_PERIOD;
 
+    /**
+     * Time difference between reporting crashed threads.
+     *
+     * @see TaskRunner#reportTimeout(ComputerExecutor, long)
+     */
+    private static final long REPORT_DEBOUNCE = TimeUnit.SECONDS.toNanos( 1 );
+
     /**
      * Lock used for modifications to the array of current threads.
      */
@@ -102,6 +110,8 @@ public final class ComputerThread
     private static final ReentrantLock computerLock = new ReentrantLock();
 
     private static final Condition hasWork = computerLock.newCondition();
+    private static final AtomicInteger idleWorkers = new AtomicInteger( 0 );
+    private static final Condition monitorWakeup = computerLock.newCondition();
 
     /**
      * Active queues to execute.
@@ -135,7 +145,7 @@ public final class ComputerThread
 
             if( runners == null )
             {
-                // TODO: Change the runners length on config reloads
+                // TODO: Update this on config reloads. Or possibly on world restarts?
                 runners = new TaskRunner[ComputerCraft.computer_threads];
 
                 // latency and minPeriod are scaled by 1 + floor(log2(threads)). We can afford to execute tasks for
@@ -227,9 +237,14 @@ public final class ComputerThread
 
             executor.virtualRuntime = Math.max( newRuntime, executor.virtualRuntime );
 
+            boolean wasBusy = isBusy();
             // Add to the queue, and signal the workers.
             computerQueue.add( executor );
             hasWork.signal();
+
+            // If we've transitioned into a busy state, notify the monitor. This will cause it to sleep for scaledPeriod
+            // instead of the longer wakeup duration.
+            if( !wasBusy && isBusy() ) monitorWakeup.signal();
         }
         finally
         {
@@ -346,6 +361,17 @@ public final class ComputerThread
         return !computerQueue.isEmpty();
     }
 
+    /**
+     * Check if we have more work queued than we have capacity for. Effectively a more fine-grained version of
+     * {@link #hasPendingWork()}.
+     *
+     * @return If the computer threads are busy.
+     */
+    private static boolean isBusy()
+    {
+        return computerQueue.size() > idleWorkers.get();
+    }
+
     /**
      * Observes all currently active {@link TaskRunner}s and terminates their tasks once they have exceeded the hard
      * abort limit.
@@ -357,76 +383,93 @@ public final class ComputerThread
         @Override
         public void run()
         {
-            try
+            while( true )
             {
-                while( true )
+                computerLock.lock();
+                try
                 {
-                    Thread.sleep( MONITOR_WAKEUP );
+                    // If we've got more work than we have capacity for it, then we'll need to pause a task soon, so
+                    // sleep for a single pause duration. Otherwise we only need to wake up to set the soft/hard abort
+                    // flags, which are far less granular.
+                    monitorWakeup.awaitNanos( isBusy() ? scaledPeriod() : MONITOR_WAKEUP );
+                }
+                catch( InterruptedException e )
+                {
+                    ComputerCraft.log.error( "Monitor thread interrupted. Computers may behave very badly!", e );
+                    break;
+                }
+                finally
+                {
+                    computerLock.unlock();
+                }
 
-                    TaskRunner[] currentRunners = ComputerThread.runners;
-                    if( currentRunners != null )
+                checkRunners();
+            }
+        }
+
+        private static void checkRunners()
+        {
+            TaskRunner[] currentRunners = ComputerThread.runners;
+            if( currentRunners == null ) return;
+
+            for( int i = 0; i < currentRunners.length; i++ )
+            {
+                TaskRunner runner = currentRunners[i];
+                // If we've no runner, skip.
+                if( runner == null || runner.owner == null || !runner.owner.isAlive() )
+                {
+                    if( !running ) continue;
+
+                    // Mark the old runner as dead and start a new one.
+                    ComputerCraft.log.warn( "Previous runner ({}) has crashed, restarting!",
+                        runner != null && runner.owner != null ? runner.owner.getName() : runner );
+                    if( runner != null ) runner.running = false;
+                    runnerFactory.newThread( runners[i] = new TaskRunner() ).start();
+                }
+
+                // If the runner has no work, skip
+                ComputerExecutor executor = runner.currentExecutor.get();
+                if( executor == null ) continue;
+
+                // Refresh the timeout state. Will set the pause/soft timeout flags as appropriate.
+                executor.timeout.refresh();
+
+                // If we're still within normal execution times (TIMEOUT) or soft abort (ABORT_TIMEOUT),
+                // then we can let the Lua machine do its work.
+                long afterStart = executor.timeout.nanoCumulative();
+                long afterHardAbort = afterStart - TIMEOUT - ABORT_TIMEOUT;
+                if( afterHardAbort < 0 ) continue;
+
+                // Set the hard abort flag.
+                executor.timeout.hardAbort();
+                executor.abort();
+
+                if( afterHardAbort >= ABORT_TIMEOUT * 2 )
+                {
+                    // If we've hard aborted and interrupted, and we're still not dead, then mark the runner
+                    // as dead, finish off the task, and spawn a new runner.
+                    runner.reportTimeout( executor, afterStart );
+                    runner.running = false;
+                    runner.owner.interrupt();
+
+                    ComputerExecutor thisExecutor = runner.currentExecutor.getAndSet( null );
+                    if( thisExecutor != null ) afterWork( runner, executor );
+
+                    synchronized( threadLock )
                     {
-                        for( int i = 0; i < currentRunners.length; i++ )
+                        if( running && runners.length > i && runners[i] == runner )
                         {
-                            TaskRunner runner = currentRunners[i];
-                            // If we've no runner, skip.
-                            if( runner == null || runner.owner == null || !runner.owner.isAlive() )
-                            {
-                                if( !running ) continue;
-
-                                // Mark the old runner as dead and start a new one.
-                                ComputerCraft.log.warn( "Previous runner ({}) has crashed, restarting!",
-                                    runner != null && runner.owner != null ? runner.owner.getName() : runner );
-                                if( runner != null ) runner.running = false;
-                                runnerFactory.newThread( runners[i] = new TaskRunner() ).start();
-                            }
-
-                            // If the runner has no work, skip
-                            ComputerExecutor executor = runner.currentExecutor.get();
-                            if( executor == null ) continue;
-
-                            // If we're still within normal execution times (TIMEOUT) or soft abort (ABORT_TIMEOUT),
-                            // then we can let the Lua machine do its work.
-                            long afterStart = executor.timeout.nanoCumulative();
-                            long afterHardAbort = afterStart - TIMEOUT - ABORT_TIMEOUT;
-                            if( afterHardAbort < 0 ) continue;
-
-                            // Set the hard abort flag.
-                            executor.timeout.hardAbort();
-                            executor.abort();
-
-                            if( afterHardAbort >= ABORT_TIMEOUT )
-                            {
-                                // If we've hard aborted but we're still not dead, dump the stack trace and interrupt
-                                // the task.
-                                timeoutTask( executor, runner.owner, afterStart );
-                                runner.owner.interrupt();
-                            }
-                            else if( afterHardAbort >= ABORT_TIMEOUT * 2 )
-                            {
-                                // If we've hard aborted and interrupted, and we're still not dead, then mark the runner
-                                // as dead, finish off the task, and spawn a new runner.
-                                timeoutTask( executor, runner.owner, afterStart );
-                                runner.running = false;
-                                runner.owner.interrupt();
-
-                                ComputerExecutor thisExecutor = runner.currentExecutor.getAndSet( null );
-                                if( thisExecutor != null ) afterWork( runner, executor );
-
-                                synchronized( threadLock )
-                                {
-                                    if( running && runners.length > i && runners[i] == runner )
-                                    {
-                                        runnerFactory.newThread( currentRunners[i] = new TaskRunner() ).start();
-                                    }
-                                }
-                            }
+                            runnerFactory.newThread( currentRunners[i] = new TaskRunner() ).start();
                         }
                     }
                 }
-            }
-            catch( InterruptedException ignored )
-            {
+                else if( afterHardAbort >= ABORT_TIMEOUT )
+                {
+                    // If we've hard aborted but we're still not dead, dump the stack trace and interrupt
+                    // the task.
+                    runner.reportTimeout( executor, afterStart );
+                    runner.owner.interrupt();
+                }
             }
         }
     }
@@ -441,6 +484,7 @@ public final class ComputerThread
     private static final class TaskRunner implements Runnable
     {
         Thread owner;
+        long lastReport = Long.MIN_VALUE;
         volatile boolean running = true;
 
         final AtomicReference<ComputerExecutor> currentExecutor = new AtomicReference<>();
@@ -460,6 +504,7 @@ public final class ComputerThread
                     computerLock.lockInterruptibly();
                     try
                     {
+                        idleWorkers.incrementAndGet();
                         while( computerQueue.isEmpty() ) hasWork.await();
                         executor = computerQueue.pollFirst();
                         assert executor != null : "hasWork should ensure we never receive null work";
@@ -467,6 +512,7 @@ public final class ComputerThread
                     finally
                     {
                         computerLock.unlock();
+                        idleWorkers.decrementAndGet();
                     }
                 }
                 catch( InterruptedException ignored )
@@ -514,27 +560,32 @@ public final class ComputerThread
                 }
             }
         }
-    }
 
-    private static void timeoutTask( ComputerExecutor executor, Thread thread, long time )
-    {
-        if( !ComputerCraft.logPeripheralErrors ) return;
-
-        StringBuilder builder = new StringBuilder()
-            .append( "Terminating computer #" ).append( executor.getComputer().getID() )
-            .append( " due to timeout (running for " ).append( time * 1e-9 )
-            .append( " seconds). This is NOT a bug, but may mean a computer is misbehaving. " )
-            .append( thread.getName() )
-            .append( " is currently " )
-            .append( thread.getState() );
-        Object blocking = LockSupport.getBlocker( thread );
-        if( blocking != null ) builder.append( "\n  on " ).append( blocking );
-
-        for( StackTraceElement element : thread.getStackTrace() )
+        private void reportTimeout( ComputerExecutor executor, long time )
         {
-            builder.append( "\n  at " ).append( element );
-        }
+            if( !ComputerCraft.logPeripheralErrors ) return;
 
-        ComputerCraft.log.warn( builder.toString() );
+            // Attempt to debounce stack trace reporting, limiting ourselves to one every second.
+            long now = System.nanoTime();
+            if( lastReport != Long.MIN_VALUE && now - lastReport - REPORT_DEBOUNCE <= 0 ) return;
+            lastReport = now;
+
+            StringBuilder builder = new StringBuilder()
+                .append( "Terminating computer #" ).append( executor.getComputer().getID() )
+                .append( " due to timeout (running for " ).append( time * 1e-9 )
+                .append( " seconds). This is NOT a bug, but may mean a computer is misbehaving. " )
+                .append( owner.getName() )
+                .append( " is currently " )
+                .append( owner.getState() );
+            Object blocking = LockSupport.getBlocker( owner );
+            if( blocking != null ) builder.append( "\n  on " ).append( blocking );
+
+            for( StackTraceElement element : owner.getStackTrace() )
+            {
+                builder.append( "\n  at " ).append( element );
+            }
+
+            ComputerCraft.log.warn( builder.toString() );
+        }
     }
 }

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

@@ -86,7 +86,7 @@ public final class TimeoutState
     /**
      * Recompute the {@link #isSoftAborted()} and {@link #isPaused()} flags.
      */
-    public void refresh()
+    public synchronized void refresh()
     {
         // Important: The weird arithmetic here is important, as nanoTime may return negative values, and so we
         // need to handle overflow.
@@ -153,7 +153,7 @@ public final class TimeoutState
      *
      * @see #nanoCumulative()
      */
-    void pauseTimer()
+    synchronized void pauseTimer()
     {
         // We set the cumulative time to difference between current time and "nominal start time".
         cumulativeElapsed = System.nanoTime() - cumulativeStart;
@@ -163,7 +163,7 @@ public final class TimeoutState
     /**
      * Resets the cumulative time and resets the abort flags.
      */
-    void stopTimer()
+    synchronized void stopTimer()
     {
         cumulativeElapsed = 0;
         paused = softAbort = hardAbort = false;

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

@@ -366,8 +366,7 @@ public class FileSystem
             Reference<?> ref;
             while( (ref = m_openFileQueue.poll()) != null )
             {
-                Closeable file = m_openFiles.remove( ref );
-                if( file != null ) IoUtil.closeQuietly( file );
+                IoUtil.closeQuietly( m_openFiles.remove( ref ) );
             }
         }
     }

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

@@ -445,24 +445,9 @@ public class CobaltLuaMachine implements ILuaMachine
             // We check our current pause/abort state every 128 instructions.
             if( (count = (count + 1) & 127) == 0 )
             {
-                // If we've been hard aborted or closed then abort.
                 if( timeout.isHardAborted() || m_state == null ) throw HardAbortError.INSTANCE;
-
-                timeout.refresh();
-                if( timeout.isPaused() )
-                {
-                    // Preserve the current state
-                    isPaused = true;
-                    oldInHook = ds.inhook;
-                    oldFlags = di.flags;
-
-                    // Suspend the state. This will probably throw, but we need to handle the case where it won't.
-                    di.flags |= FLAG_HOOKYIELD | FLAG_HOOKED;
-                    LuaThread.suspend( ds.getLuaState() );
-                    resetPaused( ds, di );
-                }
-
-                handleSoftAbort();
+                if( timeout.isPaused() ) handlePause( ds, di );
+                if( timeout.isSoftAborted() ) handleSoftAbort();
             }
 
             super.onInstruction( ds, di, pc );
@@ -471,13 +456,10 @@ public class CobaltLuaMachine implements ILuaMachine
         @Override
         public void poll() throws LuaError
         {
-            // If we've been hard aborted or closed then abort.
             LuaState state = m_state;
             if( timeout.isHardAborted() || state == null ) throw HardAbortError.INSTANCE;
-
-            timeout.refresh();
             if( timeout.isPaused() ) LuaThread.suspendBlocking( state );
-            handleSoftAbort();
+            if( timeout.isSoftAborted() ) handleSoftAbort();
         }
 
         private void resetPaused( DebugState ds, DebugFrame di )
@@ -491,11 +473,24 @@ public class CobaltLuaMachine implements ILuaMachine
         private void handleSoftAbort() throws LuaError
         {
             // If we already thrown our soft abort error then don't do it again.
-            if( !timeout.isSoftAborted() || thrownSoftAbort ) return;
+            if( thrownSoftAbort ) return;
 
             thrownSoftAbort = true;
             throw new LuaError( TimeoutState.ABORT_MESSAGE );
         }
+
+        private void handlePause( DebugState ds, DebugFrame di ) throws LuaError, UnwindThrowable
+        {
+            // Preserve the current state
+            isPaused = true;
+            oldInHook = ds.inhook;
+            oldFlags = di.flags;
+
+            // Suspend the state. This will probably throw, but we need to handle the case where it won't.
+            di.flags |= FLAG_HOOKYIELD | FLAG_HOOKED;
+            LuaThread.suspend( ds.getLuaState() );
+            resetPaused( ds, di );
+        }
     }
 
     private class CobaltLuaContext implements ILuaContext

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

@@ -5,18 +5,20 @@
  */
 package dan200.computercraft.core.terminal;
 
+import dan200.computercraft.shared.util.Colour;
 import dan200.computercraft.shared.util.Palette;
 import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.network.PacketBuffer;
 
 public class Terminal
 {
     private static final String base16 = "0123456789abcdef";
 
-    private int m_cursorX;
-    private int m_cursorY;
-    private boolean m_cursorBlink;
-    private int m_cursorColour;
-    private int m_cursorBackgroundColour;
+    private int m_cursorX = 0;
+    private int m_cursorY = 0;
+    private boolean m_cursorBlink = false;
+    private int m_cursorColour = 0;
+    private int m_cursorBackgroundColour = 15;
 
     private int m_width;
     private int m_height;
@@ -25,9 +27,9 @@ public class Terminal
     private TextBuffer[] m_textColour;
     private TextBuffer[] m_backgroundColour;
 
-    private final Palette m_palette;
+    private final Palette m_palette = new Palette();
 
-    private boolean m_changed;
+    private boolean m_changed = false;
     private final Runnable onChanged;
 
     public Terminal( int width, int height )
@@ -41,9 +43,6 @@ public class Terminal
         m_height = height;
         onChanged = changedCallback;
 
-        m_cursorColour = 0;
-        m_cursorBackgroundColour = 15;
-
         m_text = new TextBuffer[m_height];
         m_textColour = new TextBuffer[m_height];
         m_backgroundColour = new TextBuffer[m_height];
@@ -53,14 +52,6 @@ public class Terminal
             m_textColour[i] = new TextBuffer( base16.charAt( m_cursorColour ), m_width );
             m_backgroundColour[i] = new TextBuffer( base16.charAt( m_cursorBackgroundColour ), m_width );
         }
-
-        m_cursorX = 0;
-        m_cursorY = 0;
-        m_cursorBlink = false;
-
-        m_changed = false;
-
-        m_palette = new Palette();
     }
 
     public synchronized void reset()
@@ -336,6 +327,62 @@ public class Terminal
         m_changed = false;
     }
 
+    public synchronized void write( PacketBuffer buffer )
+    {
+        buffer.writeInt( m_cursorX );
+        buffer.writeInt( m_cursorY );
+        buffer.writeBoolean( m_cursorBlink );
+        buffer.writeByte( m_cursorBackgroundColour << 4 | m_cursorColour );
+
+        for( int y = 0; y < m_height; y++ )
+        {
+            TextBuffer text = m_text[y];
+            TextBuffer textColour = m_textColour[y];
+            TextBuffer backColour = m_backgroundColour[y];
+
+            for( int x = 0; x < m_width; x++ )
+            {
+                buffer.writeByte( text.charAt( x ) & 0xFF );
+                buffer.writeByte( getColour(
+                    backColour.charAt( x ), Colour.Black ) << 4 |
+                    getColour( textColour.charAt( x ), Colour.White )
+                );
+            }
+        }
+
+        m_palette.write( buffer );
+    }
+
+    public synchronized void read( PacketBuffer buffer )
+    {
+        m_cursorX = buffer.readInt();
+        m_cursorY = buffer.readInt();
+        m_cursorBlink = buffer.readBoolean();
+
+        byte cursorColour = buffer.readByte();
+        m_cursorBackgroundColour = (cursorColour >> 4) & 0xF;
+        m_cursorColour = cursorColour & 0xF;
+
+        for( int y = 0; y < m_height; y++ )
+        {
+            TextBuffer text = m_text[y];
+            TextBuffer textColour = m_textColour[y];
+            TextBuffer backColour = m_backgroundColour[y];
+
+            for( int x = 0; x < m_width; x++ )
+            {
+                text.setChar( x, (char) (buffer.readByte() & 0xFF) );
+
+                byte colour = buffer.readByte();
+                backColour.setChar( x, base16.charAt( (colour >> 4) & 0xF ) );
+                textColour.setChar( x, base16.charAt( colour & 0xF ) );
+            }
+        }
+
+        m_palette.read( buffer );
+        setChanged();
+    }
+
     public synchronized NBTTagCompound writeToNBT( NBTTagCompound nbt )
     {
         nbt.setInteger( "term_cursorX", m_cursorX );
@@ -349,10 +396,8 @@ public class Terminal
             nbt.setString( "term_textColour_" + n, m_textColour[n].toString() );
             nbt.setString( "term_textBgColour_" + n, m_backgroundColour[n].toString() );
         }
-        if( m_palette != null )
-        {
-            m_palette.writeToNBT( nbt );
-        }
+
+        m_palette.writeToNBT( nbt );
         return nbt;
     }
 
@@ -382,10 +427,15 @@ public class Terminal
                 m_backgroundColour[n].write( nbt.getString( "term_textBgColour_" + n ) );
             }
         }
-        if( m_palette != null )
-        {
-            m_palette.readFromNBT( nbt );
-        }
+
+        m_palette.readFromNBT( nbt );
         setChanged();
     }
+
+    public static int getColour( char c, Colour def )
+    {
+        if( c >= '0' && c <= '9' ) return c - '0';
+        if( c >= 'a' && c <= 'f' ) return c - 'a' + 10;
+        return 15 - def.ordinal();
+    }
 }

src/main/java/dan200/computercraft/shared/Config.java

@@ -47,6 +47,7 @@ public final class Config
     private static Property defaultComputerSettings;
     private static Property debugEnabled;
     private static Property logComputerErrors;
+    private static Property commandRequireCreative;
 
     private static Property computerThreads;
     private static Property maxMainGlobalTime;
@@ -71,6 +72,7 @@ public final class Config
     private static Property modemHighAltitudeRangeDuringStorm;
     private static Property maxNotesPerTick;
     private static Property monitorRenderer;
+    private static Property monitorBandwidth;
 
     private static Property turtlesNeedFuel;
     private static Property turtleFuelLimit;
@@ -119,10 +121,14 @@ public final class Config
             logComputerErrors.setComment( "Log exceptions thrown by peripherals and other Lua objects.\n" +
                 "This makes it easier for mod authors to debug problems, but may result in log spam should people use buggy methods." );
 
+            commandRequireCreative = config.get( CATEGORY_GENERAL, "command_require_creative", ComputerCraft.commandRequireCreative );
+            commandRequireCreative.setComment( "Require players to be in creative mode and be opped in order to interact with command computers." +
+                "This is the default behaviour for vanilla's Command blocks." );
+
             setOrder(
                 CATEGORY_GENERAL,
                 computerSpaceLimit, floppySpaceLimit, maximumFilesOpen,
-                disableLua51Features, defaultComputerSettings, debugEnabled, logComputerErrors
+                disableLua51Features, defaultComputerSettings, debugEnabled, logComputerErrors, commandRequireCreative
             );
         }
 
@@ -271,10 +277,21 @@ public final class Config
                 "monitors have performance issues, you may wish to experiment with alternative renderers." );
             monitorRenderer.setValidValues( MonitorRenderer.NAMES );
 
+            monitorBandwidth = config.get( CATEGORY_PERIPHERAL, "monitor_bandwidth", (int) ComputerCraft.monitorBandwidth );
+            monitorBandwidth.setComment( "The limit to how much monitor data can be sent *per tick*. Note:\n" +
+                " - Bandwidth is measured before compression, so the data sent to the client is smaller.\n" +
+                " - This ignores the number of players a packet is sent to. Updating a monitor for one player consumes " +
+                "the same bandwidth limit as sending to 20.\n" +
+                " - A full sized monitor sends ~25kb of data. So the default (1MB) allows for ~40 monitors to be updated " +
+                "in a single tick. \n" +
+                "Set to 0 to disable." );
+            monitorBandwidth.setValidValues( MonitorRenderer.NAMES );
+            monitorBandwidth.setMinValue( 0 );
+
             setOrder(
                 CATEGORY_PERIPHERAL,
                 commandBlockEnabled, modemRange, modemHighAltitudeRange, modemRangeDuringStorm, modemHighAltitudeRangeDuringStorm, maxNotesPerTick,
-                monitorRenderer
+                monitorRenderer, monitorBandwidth
             );
         }
 
@@ -441,6 +458,7 @@ public final class Config
         ComputerCraft.default_computer_settings = defaultComputerSettings.getString();
         ComputerCraft.debug_enable = debugEnabled.getBoolean();
         ComputerCraft.logPeripheralErrors = logComputerErrors.getBoolean();
+        ComputerCraft.commandRequireCreative = commandRequireCreative.getBoolean();
 
         // Execution
         ComputerCraft.computer_threads = computerThreads.getInt();
@@ -468,6 +486,7 @@ public final class Config
         ComputerCraft.modem_rangeDuringStorm = Math.min( modemRangeDuringStorm.getInt(), MODEM_MAX_RANGE );
         ComputerCraft.modem_highAltitudeRangeDuringStorm = Math.min( modemHighAltitudeRangeDuringStorm.getInt(), MODEM_MAX_RANGE );
         ComputerCraft.monitorRenderer = MonitorRenderer.ofString( monitorRenderer.getString() );
+        ComputerCraft.monitorBandwidth = Math.max( 0, monitorBandwidth.getLong() );
 
         // Turtles
         ComputerCraft.turtlesNeedFuel = turtlesNeedFuel.getBoolean();

src/main/java/dan200/computercraft/shared/command/text/TableFormatter.java

@@ -117,4 +117,3 @@ public interface TableFormatter
         return rowId - table.getId();
     }
 }
-

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

@@ -6,7 +6,7 @@
 package dan200.computercraft.shared.common;
 
 import dan200.computercraft.core.terminal.Terminal;
-import net.minecraft.nbt.NBTTagCompound;
+import dan200.computercraft.shared.network.client.TerminalState;
 
 public class ClientTerminal implements ITerminal
 {
@@ -46,14 +46,13 @@ public class ClientTerminal implements ITerminal
         return m_colour;
     }
 
-    public void readDescription( NBTTagCompound nbt )
+    public void read( TerminalState state )
     {
-        m_colour = nbt.getBoolean( "colour" );
-        if( nbt.hasKey( "terminal" ) )
+        m_colour = state.colour;
+        if( state.hasTerminal() )
         {
-            NBTTagCompound terminal = nbt.getCompoundTag( "terminal" );
-            resizeTerminal( terminal.getInteger( "term_width" ), terminal.getInteger( "term_height" ) );
-            m_terminal.readFromNBT( terminal );
+            resizeTerminal( state.width, state.height );
+            state.apply( m_terminal );
         }
         else
         {

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

@@ -6,7 +6,7 @@
 package dan200.computercraft.shared.common;
 
 import dan200.computercraft.core.terminal.Terminal;
-import net.minecraft.nbt.NBTTagCompound;
+import dan200.computercraft.shared.network.client.TerminalState;
 
 import java.util.concurrent.atomic.AtomicBoolean;
 
@@ -69,8 +69,6 @@ public class ServerTerminal implements ITerminal
         return m_terminalChangedLastFrame;
     }
 
-    // ITerminal implementation
-
     @Override
     public Terminal getTerminal()
     {
@@ -83,18 +81,8 @@ public class ServerTerminal implements ITerminal
         return m_colour;
     }
 
-    // Networking stuff
-
-    public void writeDescription( NBTTagCompound nbt )
+    public TerminalState write()
     {
-        nbt.setBoolean( "colour", m_colour );
-        if( m_terminal != null )
-        {
-            NBTTagCompound terminal = new NBTTagCompound();
-            terminal.setInteger( "term_width", m_terminal.getWidth() );
-            terminal.setInteger( "term_height", m_terminal.getHeight() );
-            m_terminal.writeToNBT( terminal );
-            nbt.setTag( "terminal", terminal );
-        }
+        return new TerminalState( m_colour, m_terminal );
     }
 }

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

@@ -128,7 +128,7 @@ public abstract class BlockComputerBase extends BlockDirectional
             if( tile instanceof TileComputerBase )
             {
                 TileComputerBase computer = (TileComputerBase) tile;
-                if( !player.capabilities.isCreativeMode || computer.getLabel() != null )
+                if( !player.capabilities.isCreativeMode || computer.getLabel() != null || computer.getComputerID() != -1 )
                 {
                     spawnAsEntity( world, pos, getItem( computer ) );
                 }

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

@@ -45,4 +45,3 @@ public enum ComputerState implements IStringSerializable
         return ordinal < 0 || ordinal >= VALUES.length ? ComputerState.Off : VALUES[ordinal];
     }
 }
-

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

@@ -5,6 +5,7 @@
  */
 package dan200.computercraft.shared.computer.blocks;
 
+import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.shared.computer.apis.CommandAPI;
 import dan200.computercraft.shared.computer.core.ServerComputer;
 import io.netty.buffer.ByteBuf;
@@ -167,6 +168,11 @@ public class TileCommandComputer extends TileComputer
 
     @Override
     public boolean isUsable( EntityPlayer player, boolean ignoreRange )
+    {
+        return isUsable( player ) && super.isUsable( player, ignoreRange );
+    }
+
+    public static boolean isUsable( EntityPlayer player )
     {
         MinecraftServer server = player.getServer();
         if( server == null || !server.isCommandBlockEnabled() )
@@ -174,14 +180,12 @@ public class TileCommandComputer extends TileComputer
             player.sendMessage( new TextComponentTranslation( "advMode.notEnabled" ) );
             return false;
         }
-        else if( !player.canUseCommandBlock() )
+        else if( ComputerCraft.commandRequireCreative ? !player.canUseCommandBlock() : !server.getPlayerList().canSendCommands( player.getGameProfile() ) )
         {
             player.sendMessage( new TextComponentTranslation( "advMode.notAllowed" ) );
             return false;
         }
-        else
-        {
-            return super.isUsable( player, ignoreRange );
-        }
+
+        return true;
     }
 }

src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java

@@ -155,9 +155,7 @@ public class ServerComputer extends ServerTerminal implements IComputer, IComput
 
     protected IMessage createTerminalPacket()
     {
-        NBTTagCompound tagCompound = new NBTTagCompound();
-        writeDescription( tagCompound );
-        return new ComputerTerminalClientMessage( getInstanceID(), tagCompound );
+        return new ComputerTerminalClientMessage( getInstanceID(), write() );
     }
 
     public void broadcastState( boolean force )

src/main/java/dan200/computercraft/shared/computer/inventory/ContainerViewComputer.java

@@ -6,11 +6,10 @@
 package dan200.computercraft.shared.computer.inventory;
 
 import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.computer.blocks.TileCommandComputer;
 import dan200.computercraft.shared.computer.core.*;
 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;
@@ -46,19 +45,9 @@ public class ContainerViewComputer extends Container implements IContainerComput
             }
 
             // If we're a command computer then ensure we're in creative
-            if( serverComputer.getFamily() == ComputerFamily.Command )
+            if( serverComputer.getFamily() == ComputerFamily.Command && !TileCommandComputer.isUsable( player ) )
             {
-                MinecraftServer server = player.getServer();
-                if( server == null || !server.isCommandBlockEnabled() )
-                {
-                    player.sendMessage( new TextComponentTranslation( "advMode.notEnabled" ) );
-                    return false;
-                }
-                else if( !player.canUseCommandBlock() )
-                {
-                    player.sendMessage( new TextComponentTranslation( "advMode.notAllowed" ) );
-                    return false;
-                }
+                return false;
             }
         }
 

src/main/java/dan200/computercraft/shared/computer/items/ComputerItemFactory.java

@@ -19,9 +19,7 @@ public final class ComputerItemFactory
     @Nonnull
     public static ItemStack create( TileComputer tile )
     {
-        String label = tile.getLabel();
-        int id = label != null ? tile.getComputerID() : -1;
-        return create( id, label, tile.getFamily() );
+        return create( tile.getComputerID(), tile.getLabel(), tile.getFamily() );
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/computer/items/ItemComputerBase.java

@@ -39,7 +39,7 @@ public abstract class ItemComputerBase extends ItemBlock implements IComputerIte
     @Override
     public void addInformation( @Nonnull ItemStack stack, @Nullable World world, @Nonnull List<String> list, @Nonnull ITooltipFlag flag )
     {
-        if( flag.isAdvanced() )
+        if( flag.isAdvanced() || getLabel( stack ) == null )
         {
             int id = getComputerID( stack );
             if( id >= 0 ) list.add( StringUtil.translateFormatted( "gui.computercraft.tooltip.computer_id", id ) );

src/main/java/dan200/computercraft/shared/media/items/ItemDiskLegacy.java

@@ -80,7 +80,7 @@ public class ItemDiskLegacy extends Item implements IMedia, IColouredItem
     @Override
     public void addInformation( @Nonnull ItemStack stack, World world, List<String> list, ITooltipFlag flag )
     {
-        if( flag.isAdvanced() )
+        if( flag.isAdvanced() || getLabel( stack ) == null )
         {
             int id = getDiskID( stack );
             if( id >= 0 ) list.add( StringUtil.translateFormatted( "gui.computercraft.tooltip.disk_id", id ) );

src/main/java/dan200/computercraft/shared/network/NetworkHandler.java

@@ -45,6 +45,7 @@ public final class NetworkHandler
         registerMainThread( 12, Side.CLIENT, ComputerDeletedClientMessage::new );
         registerMainThread( 13, Side.CLIENT, ComputerTerminalClientMessage::new );
         registerMainThread( 14, Side.CLIENT, PlayRecordClientMessage::new );
+        registerMainThread( 15, Side.CLIENT, MonitorClientMessage::new );
     }
 
     public static void sendToPlayer( EntityPlayer player, IMessage packet )
@@ -67,6 +68,11 @@ public final class NetworkHandler
         network.sendToAllAround( packet, point );
     }
 
+    public static void sendToAllTracking( IMessage packet, NetworkRegistry.TargetPoint point )
+    {
+        network.sendToAllTracking( packet, point );
+    }
+
     /**
      * /**
      * Register packet, and a thread-unsafe handler for it.

src/main/java/dan200/computercraft/shared/network/client/ComputerTerminalClientMessage.java

@@ -5,8 +5,6 @@
  */
 package dan200.computercraft.shared.network.client;
 
-import dan200.computercraft.shared.util.NBTUtil;
-import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.network.PacketBuffer;
 import net.minecraftforge.fml.common.network.simpleimpl.MessageContext;
 
@@ -14,12 +12,12 @@ import javax.annotation.Nonnull;
 
 public class ComputerTerminalClientMessage extends ComputerClientMessage
 {
-    private NBTTagCompound tag;
+    private TerminalState state;
 
-    public ComputerTerminalClientMessage( int instanceId, NBTTagCompound tag )
+    public ComputerTerminalClientMessage( int instanceId, TerminalState state )
     {
         super( instanceId );
-        this.tag = tag;
+        this.state = state;
     }
 
     public ComputerTerminalClientMessage()
@@ -30,19 +28,19 @@ public class ComputerTerminalClientMessage extends ComputerClientMessage
     public void toBytes( @Nonnull PacketBuffer buf )
     {
         super.toBytes( buf );
-        buf.writeCompoundTag( tag ); // TODO: Do we need to compress this?
+        state.write( buf );
     }
 
     @Override
     public void fromBytes( @Nonnull PacketBuffer buf )
     {
         super.fromBytes( buf );
-        tag = NBTUtil.readCompoundTag( buf );
+        state = new TerminalState( buf );
     }
 
     @Override
     public void handle( MessageContext context )
     {
-        getComputer().readDescription( tag );
+        getComputer().read( state );
     }
 }

src/main/java/dan200/computercraft/shared/network/client/MonitorClientMessage.java

@@ -0,0 +1,60 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2020. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.network.client;
+
+import dan200.computercraft.shared.network.NetworkMessage;
+import dan200.computercraft.shared.peripheral.monitor.TileMonitor;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.entity.EntityPlayerSP;
+import net.minecraft.network.PacketBuffer;
+import net.minecraft.tileentity.TileEntity;
+import net.minecraft.util.math.BlockPos;
+import net.minecraftforge.fml.common.network.simpleimpl.MessageContext;
+
+import javax.annotation.Nonnull;
+
+public class MonitorClientMessage implements NetworkMessage
+{
+    private BlockPos pos;
+    private TerminalState state;
+
+    public MonitorClientMessage( BlockPos pos, TerminalState state )
+    {
+        this.pos = pos;
+        this.state = state;
+    }
+
+    public MonitorClientMessage()
+    {
+    }
+
+    @Override
+    public void toBytes( @Nonnull PacketBuffer buf )
+    {
+        buf.writeBlockPos( pos );
+        state.write( buf );
+    }
+
+    @Override
+    public void fromBytes( @Nonnull PacketBuffer buf )
+    {
+        pos = buf.readBlockPos();
+        state = new TerminalState( buf );
+    }
+
+    @Override
+    public void handle( MessageContext context )
+    {
+        EntityPlayerSP player = Minecraft.getMinecraft().player;
+        if( player == null || player.world == null ) return;
+
+        TileEntity te = player.world.getTileEntity( pos );
+        if( !(te instanceof TileMonitor) ) return;
+
+        ((TileMonitor) te).read( state );
+    }
+}

src/main/java/dan200/computercraft/shared/network/client/TerminalState.java

@@ -0,0 +1,183 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2020. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.network.client;
+
+import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.shared.util.IoUtil;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufInputStream;
+import io.netty.buffer.ByteBufOutputStream;
+import io.netty.buffer.Unpooled;
+import net.minecraft.network.PacketBuffer;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.UncheckedIOException;
+import java.util.zip.GZIPInputStream;
+import java.util.zip.GZIPOutputStream;
+
+/**
+ * A snapshot of a terminal's state.
+ *
+ * This is somewhat memory inefficient (we build a buffer, only to write it elsewhere), however it means we get a
+ * complete and accurate description of a terminal, which avoids a lot of complexities with resizing terminals, dirty
+ * states, etc...
+ */
+public class TerminalState
+{
+    public final boolean colour;
+
+    public final int width;
+    public final int height;
+
+    private final boolean compress;
+
+    @Nullable
+    private final ByteBuf buffer;
+
+    private ByteBuf compressed;
+
+    public TerminalState( boolean colour, @Nullable Terminal terminal )
+    {
+        this( colour, terminal, true );
+    }
+
+    public TerminalState( boolean colour, @Nullable Terminal terminal, boolean compress )
+    {
+        this.colour = colour;
+        this.compress = compress;
+
+        if( terminal == null )
+        {
+            this.width = this.height = 0;
+            this.buffer = null;
+        }
+        else
+        {
+            this.width = terminal.getWidth();
+            this.height = terminal.getHeight();
+
+            ByteBuf buf = this.buffer = Unpooled.buffer();
+            terminal.write( new PacketBuffer( buf ) );
+        }
+    }
+
+    public TerminalState( PacketBuffer buf )
+    {
+        this.colour = buf.readBoolean();
+        this.compress = buf.readBoolean();
+
+        if( buf.readBoolean() )
+        {
+            this.width = buf.readVarInt();
+            this.height = buf.readVarInt();
+
+            int length = buf.readVarInt();
+            this.buffer = readCompressed( buf, length, compress );
+        }
+        else
+        {
+            this.width = this.height = 0;
+            this.buffer = null;
+        }
+    }
+
+    public void write( PacketBuffer buf )
+    {
+        buf.writeBoolean( colour );
+        buf.writeBoolean( compress );
+
+        buf.writeBoolean( buffer != null );
+        if( buffer != null )
+        {
+            buf.writeVarInt( width );
+            buf.writeVarInt( height );
+
+            ByteBuf sendBuffer = getCompressed();
+            buf.writeVarInt( sendBuffer.readableBytes() );
+            buf.writeBytes( sendBuffer, sendBuffer.readerIndex(), sendBuffer.readableBytes() );
+        }
+    }
+
+    public boolean hasTerminal()
+    {
+        return buffer != null;
+    }
+
+    public int size()
+    {
+        return buffer == null ? 0 : buffer.readableBytes();
+    }
+
+    public void apply( Terminal terminal )
+    {
+        if( buffer == null ) throw new NullPointerException( "buffer" );
+        terminal.read( new PacketBuffer( buffer ) );
+    }
+
+    private ByteBuf getCompressed()
+    {
+        if( buffer == null ) throw new NullPointerException( "buffer" );
+        if( !compress ) return buffer;
+        if( compressed != null ) return compressed;
+
+        ByteBuf compressed = Unpooled.directBuffer();
+        OutputStream stream = null;
+        try
+        {
+            stream = new GZIPOutputStream( new ByteBufOutputStream( compressed ) );
+            stream.write( buffer.array(), buffer.arrayOffset(), buffer.readableBytes() );
+        }
+        catch( IOException e )
+        {
+            throw new UncheckedIOException( e );
+        }
+        finally
+        {
+            IoUtil.closeQuietly( stream );
+        }
+
+        return this.compressed = compressed;
+    }
+
+    private static ByteBuf readCompressed( ByteBuf buf, int length, boolean compress )
+    {
+        if( compress )
+        {
+            ByteBuf buffer = Unpooled.buffer();
+            InputStream stream = null;
+            try
+            {
+                stream = new GZIPInputStream( new ByteBufInputStream( buf, length ) );
+                byte[] swap = new byte[8192];
+                while( true )
+                {
+                    int bytes = stream.read( swap );
+                    if( bytes == -1 ) break;
+                    buffer.writeBytes( swap, 0, bytes );
+                }
+            }
+            catch( IOException e )
+            {
+                throw new UncheckedIOException( e );
+            }
+            finally
+            {
+                IoUtil.closeQuietly( stream );
+            }
+            return buffer;
+        }
+        else
+        {
+            ByteBuf buffer = Unpooled.buffer( length );
+            buf.readBytes( buffer, length );
+            return buffer;
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/peripheral/modem/wired/TileCable.java

@@ -24,6 +24,7 @@ import net.minecraft.entity.player.EntityPlayer;
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.EnumHand;
+import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.util.text.TextComponentTranslation;
@@ -444,4 +445,11 @@ public class TileCable extends TileGeneric implements IPeripheralTile
         IBlockState state = getBlockState();
         return BlockCable.getPeripheralType( state );
     }
+
+    @Nonnull
+    @Override
+    public AxisAlignedBB getRenderBoundingBox()
+    {
+        return Block.FULL_BLOCK_AABB.offset( getPos() );
+    }
 }

src/main/java/dan200/computercraft/shared/peripheral/monitor/ClientMonitor.java

@@ -8,10 +8,16 @@ package dan200.computercraft.shared.peripheral.monitor;
 import dan200.computercraft.client.gui.FixedWidthFontRenderer;
 import dan200.computercraft.shared.common.ClientTerminal;
 import net.minecraft.client.renderer.GLAllocation;
+import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.client.renderer.OpenGlHelper;
 import net.minecraft.client.renderer.vertex.VertexBuffer;
 import net.minecraft.util.math.BlockPos;
 import net.minecraftforge.fml.relauncher.Side;
 import net.minecraftforge.fml.relauncher.SideOnly;
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL15;
+import org.lwjgl.opengl.GL30;
+import org.lwjgl.opengl.GL31;
 
 import java.util.HashSet;
 import java.util.Iterator;
@@ -26,6 +32,8 @@ public final class ClientMonitor extends ClientTerminal
     public long lastRenderFrame = -1;
     public BlockPos lastRenderPos = null;
 
+    public int tboBuffer;
+    public int tboTexture;
     public VertexBuffer buffer;
     public int displayList = 0;
 
@@ -43,7 +51,7 @@ public final class ClientMonitor extends ClientTerminal
     /**
      * Create the appropriate buffer if needed.
      *
-     * @param renderer The renderer to use. This can be fetched from {@link #renderer()}.
+     * @param renderer The renderer to use. This can be fetched from {@link MonitorRenderer#current()}.
      * @return If a buffer was created. This will return {@code false} if we already have an appropriate buffer,
      * or this mode does not require one.
      */
@@ -52,6 +60,26 @@ public final class ClientMonitor extends ClientTerminal
     {
         switch( renderer )
         {
+            case TBO:
+            {
+                if( tboBuffer != 0 ) return false;
+
+                deleteBuffers();
+
+                tboBuffer = OpenGlHelper.glGenBuffers();
+                OpenGlHelper.glBindBuffer( GL31.GL_TEXTURE_BUFFER, tboBuffer );
+                GL15.glBufferData( GL31.GL_TEXTURE_BUFFER, 0, GL15.GL_STATIC_DRAW );
+                tboTexture = GlStateManager.generateTexture();
+                GL11.glBindTexture( GL31.GL_TEXTURE_BUFFER, tboTexture );
+                GL31.glTexBuffer( GL31.GL_TEXTURE_BUFFER, GL30.GL_R8, tboBuffer );
+                GL11.glBindTexture( GL31.GL_TEXTURE_BUFFER, 0 );
+
+                OpenGlHelper.glBindBuffer( GL31.GL_TEXTURE_BUFFER, 0 );
+
+                addMonitor();
+                return true;
+            }
+
             case VBO:
                 if( buffer != null ) return false;
 
@@ -59,6 +87,7 @@ public final class ClientMonitor extends ClientTerminal
                 buffer = new VertexBuffer( FixedWidthFontRenderer.POSITION_COLOR_TEX );
                 addMonitor();
                 return true;
+
             case DISPLAY_LIST:
                 if( displayList != 0 ) return false;
 
@@ -82,6 +111,19 @@ public final class ClientMonitor extends ClientTerminal
 
     private void deleteBuffers()
     {
+
+        if( tboBuffer != 0 )
+        {
+            OpenGlHelper.glDeleteBuffers( tboBuffer );
+            tboBuffer = 0;
+        }
+
+        if( tboTexture != 0 )
+        {
+            GlStateManager.deleteTexture( tboTexture );
+            tboTexture = 0;
+        }
+
         if( buffer != null )
         {
             buffer.deleteGlBuffers();
@@ -98,7 +140,7 @@ public final class ClientMonitor extends ClientTerminal
     @SideOnly( Side.CLIENT )
     public void destroy()
     {
-        if( buffer != null || displayList != 0 )
+        if( tboBuffer != 0 || buffer != null || displayList != 0 )
         {
             synchronized( allMonitors )
             {

src/main/java/dan200/computercraft/shared/peripheral/monitor/MonitorRenderer.java

@@ -9,6 +9,7 @@ package dan200.computercraft.shared.peripheral.monitor;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.client.render.TileEntityMonitorRenderer;
 import net.minecraft.client.renderer.OpenGlHelper;
+import org.lwjgl.opengl.GLContext;
 
 import javax.annotation.Nonnull;
 import java.util.Locale;
@@ -27,7 +28,14 @@ public enum MonitorRenderer
     BEST,
 
     /**
-     * Render using VBOs. This is the default when supported.
+     * Render using texture buffer objects.
+     *
+     * @see org.lwjgl.opengl.GL31#glTexBuffer(int, int, int)
+     */
+    TBO,
+
+    /**
+     * Render using VBOs.
      *
      * @see net.minecraft.client.renderer.vertex.VertexBuffer
      */
@@ -84,6 +92,16 @@ public enum MonitorRenderer
         {
             case BEST:
                 return best();
+            case TBO:
+                checkCapabilities();
+                if( !textureBuffer )
+                {
+                    ComputerCraft.log.warn( "Texture buffers are not supported on your graphics card. Falling back to default." );
+                    ComputerCraft.monitorRenderer = BEST;
+                    return best();
+                }
+
+                return TBO;
             case VBO:
                 if( !OpenGlHelper.vboSupported )
                 {
@@ -100,6 +118,20 @@ public enum MonitorRenderer
 
     private static MonitorRenderer best()
     {
-        return OpenGlHelper.vboSupported ? VBO : DISPLAY_LIST;
+        checkCapabilities();
+        if( textureBuffer ) return TBO;
+        if( OpenGlHelper.vboSupported ) return VBO;
+        return DISPLAY_LIST;
+    }
+
+    private static boolean initialised = false;
+    private static boolean textureBuffer = false;
+
+    private static void checkCapabilities()
+    {
+        if( initialised ) return;
+
+        textureBuffer = GLContext.getCapabilities().OpenGL31;
+        initialised = true;
     }
 }

src/main/java/dan200/computercraft/shared/peripheral/monitor/MonitorWatcher.java

@@ -0,0 +1,102 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2020. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.peripheral.monitor;
+
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.network.NetworkHandler;
+import dan200.computercraft.shared.network.client.MonitorClientMessage;
+import dan200.computercraft.shared.network.client.TerminalState;
+import net.minecraft.server.management.PlayerChunkMapEntry;
+import net.minecraft.tileentity.TileEntity;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.World;
+import net.minecraft.world.WorldServer;
+import net.minecraft.world.chunk.Chunk;
+import net.minecraftforge.common.DimensionManager;
+import net.minecraftforge.event.world.ChunkWatchEvent;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
+import net.minecraftforge.fml.common.gameevent.TickEvent;
+import net.minecraftforge.fml.common.network.NetworkRegistry;
+
+import java.util.ArrayDeque;
+import java.util.Queue;
+
+@Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID )
+public final class MonitorWatcher
+{
+    private static final Queue<TileMonitor> watching = new ArrayDeque<>();
+
+    private MonitorWatcher()
+    {
+    }
+
+    static void enqueue( TileMonitor monitor )
+    {
+        if( monitor.enqueued ) return;
+
+        monitor.enqueued = true;
+        monitor.cached = null;
+        watching.add( monitor );
+    }
+
+    @SubscribeEvent
+    public static void onWatch( ChunkWatchEvent.Watch event )
+    {
+        Chunk chunk = event.getChunkInstance();
+        if( chunk == null ) return;
+
+        for( TileEntity te : chunk.getTileEntityMap().values() )
+        {
+            // Find all origin monitors who are not already on the queue.
+            if( !(te instanceof TileMonitor) ) continue;
+
+            TileMonitor monitor = (TileMonitor) te;
+            ServerMonitor serverMonitor = getMonitor( monitor );
+            if( serverMonitor == null || monitor.enqueued ) continue;
+
+            // We use the cached terminal state if available - this is guaranteed to
+            TerminalState state = monitor.cached;
+            if( state == null ) state = monitor.cached = serverMonitor.write();
+            NetworkHandler.sendToPlayer( event.getPlayer(), new MonitorClientMessage( monitor.getPos(), state ) );
+        }
+    }
+
+    @SubscribeEvent
+    public static void onTick( TickEvent.ServerTickEvent event )
+    {
+        if( event.phase != TickEvent.Phase.END ) return;
+
+        long limit = ComputerCraft.monitorBandwidth;
+        boolean obeyLimit = limit > 0;
+
+        TileMonitor tile;
+        while( (!obeyLimit || limit > 0) && (tile = watching.poll()) != null )
+        {
+            tile.enqueued = false;
+            ServerMonitor monitor = getMonitor( tile );
+            if( monitor == null ) continue;
+
+            BlockPos pos = tile.getPos();
+            World world = tile.getWorld();
+            WorldServer serverWorld = world instanceof WorldServer ? (WorldServer) world : DimensionManager.getWorld( world.provider.getDimension() );
+            PlayerChunkMapEntry entry = serverWorld.getPlayerChunkMap().getEntry( pos.getX() >> 4, pos.getZ() >> 4 );
+            if( entry == null || entry.getWatchingPlayers().isEmpty() ) continue;
+
+            NetworkRegistry.TargetPoint point = new NetworkRegistry.TargetPoint( world.provider.getDimension(), pos.getX(), pos.getY(), pos.getZ(), 0 );
+            TerminalState state = tile.cached = monitor.write();
+            NetworkHandler.sendToAllTracking( new MonitorClientMessage( pos, state ), point );
+
+            limit -= state.size();
+        }
+    }
+
+    private static ServerMonitor getMonitor( TileMonitor monitor )
+    {
+        return !monitor.isInvalid() && monitor.getXIndex() == 0 && monitor.getYIndex() == 0 ? monitor.getCachedServerMonitor() : null;
+    }
+}

src/main/java/dan200/computercraft/shared/peripheral/monitor/TileMonitor.java

@@ -5,12 +5,14 @@
  */
 package dan200.computercraft.shared.peripheral.monitor;
 
+import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheralTile;
 import dan200.computercraft.core.terminal.Terminal;
 import dan200.computercraft.shared.common.ServerTerminal;
 import dan200.computercraft.shared.common.TileGeneric;
+import dan200.computercraft.shared.network.client.TerminalState;
 import dan200.computercraft.shared.peripheral.PeripheralType;
 import dan200.computercraft.shared.peripheral.common.BlockPeripheral;
 import dan200.computercraft.shared.peripheral.common.ITilePeripheral;
@@ -46,6 +48,10 @@ public class TileMonitor extends TileGeneric implements ITilePeripheral, IPeriph
     private boolean m_destroyed = false;
     private boolean visiting = false;
 
+    // MonitorWatcher state.
+    boolean enqueued;
+    TerminalState cached;
+
     private int m_width = 1;
     private int m_height = 1;
     private int m_xIndex = 0;
@@ -148,7 +154,7 @@ public class TileMonitor extends TileGeneric implements ITilePeripheral, IPeriph
             }
         }
 
-        if( m_serverMonitor.pollTerminalChanged() ) updateBlock();
+        if( m_serverMonitor.pollTerminalChanged() ) MonitorWatcher.enqueue( this );
     }
 
     // IPeripheralTile implementation
@@ -239,11 +245,6 @@ public class TileMonitor extends TileGeneric implements ITilePeripheral, IPeriph
         nbt.setInteger( "width", m_width );
         nbt.setInteger( "height", m_height );
         nbt.setInteger( "monitorDir", m_dir );
-
-        if( m_xIndex == 0 && m_yIndex == 0 && m_serverMonitor != null )
-        {
-            m_serverMonitor.writeDescription( nbt );
-        }
     }
 
     @Override
@@ -273,9 +274,8 @@ public class TileMonitor extends TileGeneric implements ITilePeripheral, IPeriph
 
         if( m_xIndex == 0 && m_yIndex == 0 )
         {
-            // If we're the origin terminal then read the description
+            // If we're the origin terminal then create it.
             if( m_clientMonitor == null ) m_clientMonitor = new ClientMonitor( m_advanced, this );
-            m_clientMonitor.readDescription( nbt );
         }
 
         if( oldXIndex != m_xIndex || oldYIndex != m_yIndex ||
@@ -286,6 +286,19 @@ public class TileMonitor extends TileGeneric implements ITilePeripheral, IPeriph
             updateBlock();
         }
     }
+
+    public final void read( TerminalState state )
+    {
+        if( m_xIndex != 0 || m_yIndex != 0 )
+        {
+            ComputerCraft.log.warn( "Receiving monitor state for non-origin terminal at {}", getPos() );
+            return;
+        }
+
+        if( m_clientMonitor == null ) m_clientMonitor = new ClientMonitor( m_advanced, this );
+        m_clientMonitor.read( state );
+    }
+
     // Sizing and placement stuff
 
     public EnumFacing getDirection()

src/main/java/dan200/computercraft/shared/peripheral/speaker/SpeakerPeripheral.java

@@ -148,4 +148,3 @@ public abstract class SpeakerPeripheral implements IPeripheral
         return true;
     }
 }
-

src/main/java/dan200/computercraft/shared/pocket/items/ItemPocketComputer.java

@@ -211,7 +211,7 @@ public class ItemPocketComputer extends Item implements IComputerItem, IMedia, I
     @Override
     public void addInformation( @Nonnull ItemStack stack, World world, List<String> list, ITooltipFlag flag )
     {
-        if( flag.isAdvanced() )
+        if( flag.isAdvanced() || getLabel( stack ) == null )
         {
             int id = getComputerID( stack );
             if( id >= 0 ) list.add( StringUtil.translateFormatted( "gui.computercraft.tooltip.computer_id", id ) );

src/main/java/dan200/computercraft/shared/turtle/items/ItemTurtleLegacy.java

@@ -88,4 +88,3 @@ public class ItemTurtleLegacy extends ItemTurtleBase
         return 0;
     }
 }
-

src/main/java/dan200/computercraft/shared/turtle/items/TurtleItemFactory.java

@@ -6,6 +6,7 @@
 package dan200.computercraft.shared.turtle.items;
 
 import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.api.turtle.ITurtleAccess;
 import dan200.computercraft.api.turtle.ITurtleUpgrade;
 import dan200.computercraft.api.turtle.TurtleSide;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
@@ -22,18 +23,13 @@ public final class TurtleItemFactory
     @Nonnull
     public static ItemStack create( ITurtleTile turtle )
     {
-        ITurtleUpgrade leftUpgrade = turtle.getAccess().getUpgrade( TurtleSide.Left );
-        ITurtleUpgrade rightUpgrade = turtle.getAccess().getUpgrade( TurtleSide.Right );
+        ITurtleAccess access = turtle.getAccess();
 
-        String label = turtle.getLabel();
-        if( label == null )
-        {
-            return create( -1, null, turtle.getColour(), turtle.getFamily(), leftUpgrade, rightUpgrade, 0, turtle.getOverlay() );
-        }
-
-        int id = turtle.getComputerID();
-        int fuelLevel = turtle.getAccess().getFuelLevel();
-        return create( id, label, turtle.getColour(), turtle.getFamily(), leftUpgrade, rightUpgrade, fuelLevel, turtle.getOverlay() );
+        return create(
+            turtle.getComputerID(), turtle.getLabel(), turtle.getColour(), turtle.getFamily(),
+            access.getUpgrade( TurtleSide.Left ), access.getUpgrade( TurtleSide.Right ),
+            access.getFuelLevel(), turtle.getOverlay()
+        );
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/util/DropConsumer.java

@@ -13,11 +13,11 @@ import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
 import net.minecraftforge.event.entity.EntityJoinWorldEvent;
+import net.minecraftforge.event.entity.living.LivingDropsEvent;
 import net.minecraftforge.fml.common.Mod;
 import net.minecraftforge.fml.common.eventhandler.EventPriority;
 import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
 
-import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Function;
@@ -31,16 +31,16 @@ public final class DropConsumer
 
     private static Function<ItemStack, ItemStack> dropConsumer;
     private static List<ItemStack> remainingDrops;
-    private static WeakReference<World> dropWorld;
+    private static World dropWorld;
     private static AxisAlignedBB dropBounds;
-    private static WeakReference<Entity> dropEntity;
+    private static Entity dropEntity;
 
     public static void set( Entity entity, Function<ItemStack, ItemStack> consumer )
     {
         dropConsumer = consumer;
         remainingDrops = new ArrayList<>();
-        dropEntity = new WeakReference<>( entity );
-        dropWorld = new WeakReference<>( entity.world );
+        dropEntity = entity;
+        dropWorld = entity.world;
         dropBounds = new AxisAlignedBB( entity.getPosition() ).grow( 2, 2, 2 );
 
         entity.captureDrops = true;
@@ -51,26 +51,12 @@ public final class DropConsumer
         dropConsumer = consumer;
         remainingDrops = new ArrayList<>( 2 );
         dropEntity = null;
-        dropWorld = new WeakReference<>( world );
+        dropWorld = world;
         dropBounds = new AxisAlignedBB( pos ).grow( 2, 2, 2 );
     }
 
     public static List<ItemStack> clear()
     {
-        if( dropEntity != null )
-        {
-            Entity entity = dropEntity.get();
-            if( entity != null )
-            {
-                entity.captureDrops = false;
-                if( entity.capturedDrops != null )
-                {
-                    for( EntityItem entityItem : entity.capturedDrops ) handleDrops( entityItem.getItem() );
-                    entity.capturedDrops.clear();
-                }
-            }
-        }
-
         List<ItemStack> remainingStacks = remainingDrops;
 
         dropConsumer = null;
@@ -92,11 +78,20 @@ public final class DropConsumer
     public static void onEntitySpawn( EntityJoinWorldEvent event )
     {
         // Capture any nearby item spawns
-        if( dropWorld != null && dropWorld.get() == event.getWorld() && event.getEntity() instanceof EntityItem
+        if( dropWorld == event.getWorld() && event.getEntity() instanceof EntityItem
             && dropBounds.contains( event.getEntity().getPositionVector() ) )
         {
             handleDrops( ((EntityItem) event.getEntity()).getItem() );
             event.setCanceled( true );
         }
     }
+
+    @SubscribeEvent
+    public static void onLivingDrops( LivingDropsEvent drops )
+    {
+        if( dropEntity == null || drops.getEntity() != dropEntity ) return;
+
+        for( EntityItem drop : drops.getDrops() ) handleDrops( drop.getItem() );
+        drops.setCanceled( true );
+    }
 }

src/main/java/dan200/computercraft/shared/util/IoUtil.java

@@ -5,6 +5,7 @@
  */
 package dan200.computercraft.shared.util;
 
+import javax.annotation.Nullable;
 import java.io.Closeable;
 import java.io.IOException;
 
@@ -12,11 +13,11 @@ public final class IoUtil
 {
     private IoUtil() {}
 
-    public static void closeQuietly( Closeable closeable )
+    public static void closeQuietly( @Nullable Closeable closeable )
     {
         try
         {
-            closeable.close();
+            if( closeable != null ) closeable.close();
         }
         catch( IOException ignored )
         {

src/main/java/dan200/computercraft/shared/util/Palette.java

@@ -6,6 +6,7 @@
 package dan200.computercraft.shared.util;
 
 import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.network.PacketBuffer;
 
 public class Palette
 {
@@ -78,6 +79,22 @@ public class Palette
         };
     }
 
+    public void write( PacketBuffer buffer )
+    {
+        for( double[] colour : colours )
+        {
+            for( double channel : colour ) buffer.writeByte( (int) (channel * 0xFF) & 0xFF );
+        }
+    }
+
+    public void read( PacketBuffer buffer )
+    {
+        for( double[] colour : colours )
+        {
+            for( int i = 0; i < colour.length; i++ ) colour[i] = (buffer.readByte() & 0xFF) / 255.0;
+        }
+    }
+
     public NBTTagCompound writeToNBT( NBTTagCompound nbt )
     {
         int[] rgb8 = new int[colours.length];

src/main/resources/assets/computercraft/blockstates/wired_modem_full.json

@@ -6,4 +6,3 @@
         "modem=true,peripheral=true": { "model": "computercraft:wired_modem_full_on_peripheral" }
     }
 }
-

src/main/resources/assets/computercraft/lang/da_dk.lang

@@ -44,5 +44,5 @@ chat.computercraft.wired_modem.peripheral_disconnected=Perifer enhed "%s" koblet
 
 # Misc tooltips
 gui.computercraft.tooltip.copy=Kopier til udklipsholder
-gui.computercraft.tooltip.computer_id=(Computer-ID: %s)
-gui.computercraft.tooltip.disk_id=(Disk-ID: %s)
+gui.computercraft.tooltip.computer_id=Computer-ID: %s
+gui.computercraft.tooltip.disk_id=Disk-ID: %s

src/main/resources/assets/computercraft/lang/de_de.lang

@@ -148,8 +148,8 @@ tracking_field.computercraft.coroutines_dead.name=Koroutinen gelöscht
 
 # Misc tooltips
 gui.computercraft.tooltip.copy=In die Zwischenablage kopieren
-gui.computercraft.tooltip.computer_id=(Computer ID: %s)
-gui.computercraft.tooltip.disk_id=(Disketten ID: %s)
+gui.computercraft.tooltip.computer_id=Computer ID: %s
+gui.computercraft.tooltip.disk_id=Disketten ID: %s
 
 # Config options
 gui.computercraft:config.computer_space_limit=Speicherplatz von Computern (Bytes)

src/main/resources/assets/computercraft/lang/en_us.lang

@@ -148,8 +148,8 @@ tracking_field.computercraft.coroutines_dead.name=Coroutines disposed
 
 # Misc tooltips
 gui.computercraft.tooltip.copy=Copy to clipboard
-gui.computercraft.tooltip.computer_id=(Computer ID: %s)
-gui.computercraft.tooltip.disk_id=(Disk ID: %s)
+gui.computercraft.tooltip.computer_id=Computer ID: %s
+gui.computercraft.tooltip.disk_id=Disk ID: %s
 
 # Config options
 gui.computercraft:config.computer_space_limit=Computer space limit (bytes)
@@ -159,6 +159,7 @@ gui.computercraft:config.disable_lua51_features=Disable Lua 5.1 features
 gui.computercraft:config.default_computer_settings=Default Computer settings
 gui.computercraft:config.debug_enabled=Enable debug library
 gui.computercraft:config.log_computer_errors=Log computer errors
+gui.computercraft:config.command_require_creative=Command computers require creative
 
 gui.computercraft:config.execution=Execution
 gui.computercraft:config.execution.computer_threads=Computer threads
@@ -187,8 +188,10 @@ gui.computercraft:config.peripheral.modem_high_altitude_range_during_storm=Modem
 gui.computercraft:config.peripheral.max_notes_per_tick=Maximum notes that a computer can play at once
 gui.computercraft:config.peripheral.monitor_renderer=Monitor renderer
 gui.computercraft:config.peripheral.monitor_renderer.best=Best
+gui.computercraft:config.peripheral.monitor_renderer.tbo=Texture Buffers
 gui.computercraft:config.peripheral.monitor_renderer.vbo=Vertex Buffers
 gui.computercraft:config.peripheral.monitor_renderer.display_list=Display Lists
+gui.computercraft:config.peripheral.monitor_bandwidth=Monitor bandwidth
 
 gui.computercraft:config.turtle=Turtles
 gui.computercraft:config.turtle.need_fuel=Enable fuel

src/main/resources/assets/computercraft/lang/ko_kr.lang

@@ -148,8 +148,8 @@ tracking_field.computercraft.coroutines_dead.name=코루틴 처리됨
 
 # Misc tooltips
 gui.computercraft.tooltip.copy=클립보드에 복사
-gui.computercraft.tooltip.computer_id=(컴퓨터 ID: %s)
-gui.computercraft.tooltip.disk_id=(디스크 ID: %s)
+gui.computercraft.tooltip.computer_id=컴퓨터 ID: %s
+gui.computercraft.tooltip.disk_id=디스크 ID: %s
 
 # Config options
 gui.computercraft:config.computer_space_limit=컴퓨터 공간 제한 (바이트)

src/main/resources/assets/computercraft/lang/zh_cn.lang

@@ -148,8 +148,8 @@ tracking_field.computercraft.coroutines_dead.name=协同处理
 
 # Misc tooltips
 gui.computercraft.tooltip.copy=复制到剪贴板
-gui.computercraft.tooltip.computer_id=(计算机ID: %s)
-gui.computercraft.tooltip.disk_id=(磁盘ID: %s)
+gui.computercraft.tooltip.computer_id=计算机ID: %s
+gui.computercraft.tooltip.disk_id=磁盘ID: %s
 
 # Config options
 gui.computercraft:config.computer_space_limit=计算机空间限制(字节)

src/main/resources/assets/computercraft/lua/bios.lua

@@ -797,6 +797,12 @@ function fs.complete(sPath, sLocation, bIncludeFiles, bIncludeDirs)
     return tEmpty
 end
 
+function fs.isDriveRoot(sPath)
+    expect(1, sPath, "string")
+    -- Force the root directory to be a mount.
+    return fs.getDir(sPath) == ".." or fs.getDrive(sPath) ~= fs.getDrive(fs.getDir(sPath))
+end
+
 -- Load APIs
 local bAPIError = false
 local tApis = fs.list("rom/apis")
@@ -932,6 +938,23 @@ settings.define("motd.path", {
     description = [[The path to load random messages from. Should be a colon (":") separated string of file paths.]],
     type = "string",
 })
+
+settings.define("lua.warn_against_use_of_local", {
+    default = true,
+    description = [[Print a message when input in the Lua REPL starts with the word 'local'. Local variables defined in the Lua REPL are be inaccessable on the next input.]],
+    type = "boolean",
+})
+settings.define("lua.function_args", {
+    default = true,
+    description = "Show function arguments when printing functions.",
+    type = "boolean",
+})
+settings.define("lua.function_source", {
+    default = false,
+    description = "Show where a function was defined when printing functions.",
+    type = "boolean",
+})
+
 if term.isColour() then
     settings.define("bios.use_multishell", {
         default = true,

src/main/resources/assets/computercraft/lua/rom/apis/command/commands.lua

@@ -12,6 +12,9 @@
 -- [mc]: https://minecraft.gamepedia.com/Commands
 --
 -- @module commands
+-- @usage Set the block above this computer to stone:
+--
+--     commands.setblock("~", "~1", "~", "minecraft:stone")
 
 if not commands then
     error("Cannot load command API on normal computer", 2)
@@ -65,4 +68,13 @@ for _, sCommandName in ipairs(tCommands) do
         end
     end
 end
+
+--- A table containing asynchronous wrappers for all commands.
+--
+-- As with @{commands.execAsync}, this returns the "task id" of the enqueued
+-- command.
+-- @see execAsync
+-- @usage Asynchronously sets the block above the computer to stone.
+--
+--     commands.async.setblock("~", "~1", "~", "minecraft:stone")
 env.async = tAsync

src/main/resources/assets/computercraft/lua/rom/apis/io.lua

@@ -75,7 +75,10 @@ handleMetatable = {
             if not handle.read then return nil, "file is not readable" end
 
             local args = table.pack(...)
-            return function() return checkResult(self, self:read(table.unpack(args, 1, args.n))) end
+            return function()
+                if self._closed then error("file is already closed", 2) end
+                return checkResult(self, self:read(table.unpack(args, 1, args.n)))
+            end
         end,
 
         read = function(self, ...)
@@ -259,12 +262,13 @@ end
 -- instead. In this case, the handle is not used.
 --
 -- @tparam[opt] string filename The name of the file to extract lines from
+-- @param ... The argument to pass to @{Handle:read} for each line.
 -- @treturn function():string|nil The line iterator.
 -- @throws If the file cannot be opened for reading
 --
 -- @see Handle:lines
 -- @see io.input
-function lines(filename)
+function lines(filename, ...)
     expect(1, filename, "string", "nil")
     if filename then
         local ok, err = open(filename, "rb")
@@ -273,9 +277,9 @@ function lines(filename)
         -- We set this magic flag to mark this file as being opened by io.lines and so should be
         -- closed automatically
         ok._autoclose = true
-        return ok:lines()
+        return ok:lines(...)
     else
-        return currentInput:lines()
+        return currentInput:lines(...)
     end
 end
 
@@ -313,7 +317,7 @@ end
 -- @throws If the provided filename cannot be opened for writing.
 function output(file)
     if type_of(file) == "string" then
-        local res, err = open(file, "w")
+        local res, err = open(file, "wb")
         if not res then error(err, 2) end
         currentOutput = res
     elseif type_of(file) == "table" and getmetatable(file) == handleMetatable then

src/main/resources/assets/computercraft/lua/rom/apis/peripheral.lua

@@ -64,24 +64,33 @@ function isPresent(name)
     return false
 end
 
---- Get the type of the peripheral with the given name.
+--- Get the type of a wrapped peripheral, or a peripheral with the given name.
 --
--- @tparam string name The name of the peripheral to find.
+-- @tparam string|table peripheral The name of the peripheral to find, or a
+-- wrapped peripheral instance.
 -- @treturn string|nil The peripheral's type, or `nil` if it is not present.
-function getType(name)
-    expect(1, name, "string")
-    if native.isPresent(name) then
-        return native.getType(name)
-    end
-    for n = 1, #sides do
-        local side = sides[n]
-        if native.getType(side) == "modem" and not native.call(side, "isWireless") and
-            native.call(side, "isPresentRemote", name)
-        then
-            return native.call(side, "getTypeRemote", name)
+function getType(peripheral)
+    expect(1, peripheral, "string", "table")
+    if type(peripheral) == "string" then -- Peripheral name passed
+        if native.isPresent(peripheral) then
+            return native.getType(peripheral)
         end
+        for n = 1, #sides do
+            local side = sides[n]
+            if native.getType(side) == "modem" and not native.call(side, "isWireless") and
+                native.call(side, "isPresentRemote", peripheral)
+            then
+                return native.call(side, "getTypeRemote", peripheral)
+            end
+        end
+        return nil
+    else
+        local mt = getmetatable(peripheral)
+        if not mt or mt.__name ~= "peripheral" or type(mt.type) ~= "string" then
+            error("bad argument #1 (table is not a peripheral)", 2)
+        end
+        return mt.type
     end
-    return nil
 end
 
 --- Get all available methods for the peripheral with the given name.
@@ -105,6 +114,19 @@ function getMethods(name)
     return nil
 end
 
+--- Get the name of a peripheral wrapped with @{peripheral.wrap}.
+--
+-- @tparam table peripheral The peripheral to get the name of.
+-- @treturn string The name of the given peripheral.
+function getName(peripheral)
+    expect(1, peripheral, "table")
+    local mt = getmetatable(peripheral)
+    if not mt or mt.__name ~= "peripheral" or type(mt.name) ~= "string" then
+        error("bad argument #1 (table is not a peripheral)", 2)
+    end
+    return mt.name
+end
+
 --- Call a method on the peripheral with the given name.
 --
 -- @tparam string name The name of the peripheral to invoke the method on.
@@ -148,7 +170,11 @@ function wrap(name)
         return nil
     end
 
-    local result = {}
+    local result = setmetatable({}, {
+        __name = "peripheral",
+        name = name,
+        type = peripheral.getType(name),
+    })
     for _, method in ipairs(methods) do
         result[method] = function(...)
             return peripheral.call(name, method, ...)

src/main/resources/assets/computercraft/lua/rom/apis/rednet.lua

@@ -29,7 +29,7 @@ local tReceivedMessageTimeouts = {}
 local tHostnames = {}
 
 --- Opens a modem with the given @{peripheral} name, allowing it to send and
---- receive messages over rednet.
+-- receive messages over rednet.
 --
 -- This will open the modem on two channels: one which has the same
 -- @{os.getComputerID|ID} as the computer, and another on
@@ -246,7 +246,7 @@ function host(sProtocol, sHostname)
 end
 
 --- Stop @{rednet.host|hosting} a specific protocol, meaning it will no longer
---- respond to @{rednet.lookup} requests.
+-- respond to @{rednet.lookup} requests.
 --
 -- @tparam string sProtocol The protocol to unregister your self from.
 function unhost(sProtocol)
@@ -334,7 +334,11 @@ end
 
 local bRunning = false
 
---- @local
+--- Listen for modem messages and converts them into rednet messages, which may
+-- then be @{receive|received}.
+--
+-- This is automatically started in the background on computer startup, and
+-- should not be called manually.
 function run()
     if bRunning then
         error("rednet is already running", 2)

src/main/resources/assets/computercraft/lua/rom/apis/settings.lua

@@ -205,9 +205,9 @@ function load(sPath)
     end
 
     for k, v in pairs(tFile) do
-        local ty_v = type(k)
+        local ty_v = type(v)
         if type(k) == "string" and (ty_v == "string" or ty_v == "number" or ty_v == "boolean" or ty_v == "table") then
-            local opt = details[name]
+            local opt = details[k]
             if not opt or not opt.type or ty_v == opt.type then
                 set_value(k, v)
             end

src/main/resources/assets/computercraft/lua/rom/apis/turtle/turtle.lua

@@ -5,7 +5,12 @@
 if not turtle then
     error("Cannot load turtle API on computer", 2)
 end
-native = turtle.native or turtle --- @local
+
+--- The builtin turtle API, without any generated helper functions.
+--
+-- Generally you should not need to use this table - it only exists for
+-- backwards compatibility reasons.
+native = turtle.native or turtle
 
 local function addCraftMethod(object)
     if peripheral.getType("left") == "workbench" then

src/main/resources/assets/computercraft/lua/rom/help/changelog.txt

@@ -1,3 +1,36 @@
+# New features in CC: Tweaked 1.89.2
+
+* Fix dupe bug when killing an entity with a turtle.
+
+# New features in CC: Tweaked 1.89.1
+
+* Fix crashes when rendering monitors of varying sizes.
+
+# New features in CC: Tweaked 1.89.0
+
+* Compress monitor data, reducing network traffic by a significant amount.
+* Allow limiting the bandwidth monitor updates use.
+* Several optimisations to monitor rendering (@Lignum)
+
+And several bug fixes:
+* Fix settings.load failing on defined settings.
+
+# New features in CC: Tweaked 1.88.0
+
+* Computers and turtles now preserve their ID when broken.
+* Add `peripheral.getName` - returns the name of a wrapped peripheral.
+* Reduce network overhead of monitors and terminals.
+* Add a TBO backend for monitors, with a significant performance boost.
+* The Lua REPL warns when declaring locals (lupus590, exerro)
+* Add config to allow using command computers in survival.
+* Add fs.isDriveRoot - checks if a path is the root of a drive.
+* `cc.pretty` can now display a function's arguments and where it was defined. The Lua REPL will show arguments by default.
+* Move the shell's `require`/`package` implementation to a separate `cc.require` module.
+
+And several bug fixes:
+* Fix io.lines not accepting arguments.
+* Fix settings.load using an unknown global (MCJack123).
+
 # New features in CC: Tweaked 1.87.0
 
 * Add documentation to many Lua functions. This is published online at https://tweaked.cc/.

src/main/resources/assets/computercraft/lua/rom/help/credits.txt

@@ -1,4 +1,3 @@
-
 ComputerCraft was created by Daniel "dan200" Ratcliffe, with additional code by Aaron "Cloudy" Mills.
 Thanks to nitrogenfingers, GopherATL and RamiLego for program contributions.
 Thanks to Mojang, the Forge team, and the MCP team.

src/main/resources/assets/computercraft/lua/rom/help/peripheral.txt

@@ -3,6 +3,7 @@ The peripheral API is for interacting with external peripheral devices. Type "he
 Functions in the peripheral API:
 peripheral.getNames()
 peripheral.isPresent( name )
+peripheral.getName( peripheral )
 peripheral.getType( name )
 peripheral.getMethods( name )
 peripheral.call( name, methodName, param1, param2, etc )

src/main/resources/assets/computercraft/lua/rom/help/whatsnew.txt

@@ -1,31 +1,5 @@
-New features in CC: Tweaked 1.87.0
+New features in CC: Tweaked 1.89.2
 
-* Add documentation to many Lua functions. This is published online at https://tweaked.cc/.
-* Replace to pretty-printer in the Lua REPL. It now supports displaying functions and recursive tables. This printer is may be used within your own code through the `cc.pretty` module.
-* Add `fs.getCapacity`. A complement to `fs.getFreeSpace`, this returns the capacity of the supplied drive.
-* Add `fs.getAttributes`. This provides file size and type, as well as creation and modification time.
-* Update Cobalt version. This backports several features from Lua 5.2 and 5.3:
-  - The `__len` metamethod may now be used by tables.
-  - Add `\z`, hexadecimal (`\x00`) and unicode (`\u0000`) string escape codes.
-  - Add `utf8` lib.
-  - Mirror Lua's behaviour of tail calls more closely. Native functions are no longer tail called, and tail calls are displayed in the stack trace.
-  - `table.unpack` now uses `__len` and `__index` metamethods.
-  - Parser errors now include the token where the error occured.
-* Add `textutils.unserializeJSON`. This can be used to decode standard JSON and stringified-NBT.
-* Switch the monitor renderer to use VBOs, providing a _significant_ performance boost in some cases. You can switch back to the display list renderer via the config.
-* The `settings` API now allows "defining" settings. This allows settings to specify a default value and description.
-* Enable the motd on non-pocket computers.
-* Allow using the menu with the mouse in edit and paint (JakobDev).
-* Add Danish and Korean translations (ChristianLW, mindy15963)
-* Fire `mouse_up` events in the monitor program.
-* Allow specifying a timeout to `websocket.receive`.
-* Increase the maximimum limit for websocket messages.
-* Optimise capacity checking of computer/disk folders.
-
-And several bug fixes:
-* Fix turtle texture being incorrectly oriented (magiczocker10).
-* Prevent copying folders into themselves.
-* Fix race condition within ID assignment.
-* Normalise file paths within shell.setDir (JakobDev)
+* Fix dupe bug when killing an entity with a turtle.
 
 Type "help changelog" to see the full version history.

src/main/resources/assets/computercraft/lua/rom/modules/main/cc/pretty.lua

@@ -19,8 +19,12 @@
 --     local pretty = require "cc.pretty"
 --     pretty.write(pretty.group(pretty.text("hello") .. pretty.space_line .. pretty.text("world")))
 
-local expect = require "cc.expect".expect
-local type, getmetatable, setmetatable, colours, str_write = type, getmetatable, setmetatable, colours, write
+local expect = require "cc.expect"
+local expect, field = expect.expect, expect.field
+
+local type, getmetatable, setmetatable, colours, str_write, tostring = type, getmetatable, setmetatable, colours, write, tostring
+local debug_info = type(debug) == "table" and type(debug.getinfo) == "function" and debug.getinfo
+local debug_local = type(debug) == "table" and type(debug.getlocal) == "function" and debug.getlocal
 
 --- @{table.insert} alternative, but with the length stored inline.
 local function append(out, value)
@@ -343,13 +347,38 @@ local function key_compare(a, b)
     return false
 end
 
-local function pretty_impl(obj, tracking)
+local function show_function(fn, options)
+    local info = debug_info and debug_info(fn, "Su")
+
+    -- Include function source position if available
+    local name
+    if options.function_source and info and info.short_src and info.linedefined and info.linedefined >= 1 then
+        name = "function<" .. info.short_src .. ":" .. info.linedefined .. ">"
+    else
+        name = tostring(fn)
+    end
+
+    -- Include arguments if a Lua function and if available. Lua will report "C"
+    -- functions as variadic.
+    if options.function_args and info and info.what == "Lua" and info.nparams and debug_local then
+        local args = {}
+        for i = 1, info.nparams do args[i] = debug_local(fn, i) or "?" end
+        if info.isvararg then args[#args + 1] = "..." end
+        name = name .. "(" .. table.concat(args, ", ") .. ")"
+    end
+
+    return name
+end
+
+local function pretty_impl(obj, options, tracking)
     local obj_type = type(obj)
     if obj_type == "string" then
         local formatted = ("%q"):format(obj):gsub("\\\n", "\\n")
         return text(formatted, colours.red)
     elseif obj_type == "number" then
         return text(tostring(obj), colours.magenta)
+    elseif obj_type == "function" then
+        return text(show_function(obj, options), colours.lightGrey)
     elseif obj_type ~= "table" or tracking[obj] then
         return text(tostring(obj), colours.lightGrey)
     elseif getmetatable(obj) ~= nil and getmetatable(obj).__tostring then
@@ -371,20 +400,20 @@ local function pretty_impl(obj, tracking)
             local v = obj[k]
             local ty = type(k)
             if ty == "number" and k % 1 == 0 and k >= 1 and k <= length then
-                append(doc, pretty_impl(v, tracking))
+                append(doc, pretty_impl(v, options, tracking))
             elseif ty == "string" and not keywords[k] and k:match("^[%a_][%a%d_]*$") then
                 append(doc, text(k .. " = "))
-                append(doc, pretty_impl(v, tracking))
+                append(doc, pretty_impl(v, options, tracking))
             else
                 append(doc, obracket)
-                append(doc, pretty_impl(k, tracking))
+                append(doc, pretty_impl(k, options, tracking))
                 append(doc, cbracket)
-                append(doc, pretty_impl(v, tracking))
+                append(doc, pretty_impl(v, options, tracking))
             end
         end
 
         tracking[obj] = nil
-        return group(concat(obrace, nest(2, concat(table.unpack(doc, 1, n))), space_line, cbrace))
+        return group(concat(obrace, nest(2, concat(table.unpack(doc, 1, doc.n))), space_line, cbrace))
     end
 end
 
@@ -393,12 +422,24 @@ end
 -- This can then be rendered with @{write} or @{print}.
 --
 -- @param obj The object to pretty-print.
+-- @tparam[opt] { function_args = boolean, function_source = boolean } options
+-- Controls how various properties are displayed.
+--  - `function_args`: Show the arguments to a function if known (`false` by default).
+--  - `function_source`: Show where the function was defined, instead of
+--    `function: xxxxxxxx` (`false` by default).
 -- @treturn Doc The object formatted as a document.
 -- @usage Display a table on the screen
 --     local pretty = require "cc.pretty"
 --     pretty.print(pretty.pretty({ 1, 2, 3 }))
-local function pretty(obj)
-    return pretty_impl(obj, {})
+local function pretty(obj, options)
+    expect(2, options, "table", "nil")
+    options = options or {}
+
+    local actual_options = {
+        function_source = field(options, "function_source", "boolean", "nil") or false,
+        function_args = field(options, "function_args", "boolean", "nil") or false,
+    }
+    return pretty_impl(obj, actual_options, {})
 end
 
 return {

src/main/resources/assets/computercraft/lua/rom/modules/main/cc/require.lua

@@ -0,0 +1,121 @@
+--- This provides a pure Lua implementation of the builtin @{require} function
+-- and @{package} library.
+--
+-- Generally you do not need to use this module - it is injected into the
+-- every program's environment. However, it may be useful when building a
+-- custom shell or when running programs yourself.
+--
+-- @module cc.require
+-- @usage Construct the package and require function, and insert them into a
+-- custom environment.
+--
+--     local env = setmetatable({}, { __index = _ENV })
+--     local r = require "cc.require"
+--     env.require, env.package = r.make(env, "/")
+
+local expect = require and require("cc.expect") or dofile("rom/modules/main/cc/expect.lua")
+local expect = expect.expect
+
+local function preload(package)
+    return function(name)
+        if package.preload[name] then
+            return package.preload[name]
+        else
+            return nil, "no field package.preload['" .. name .. "']"
+        end
+    end
+end
+
+local function from_file(package, env, dir)
+    return function(name)
+        local fname = string.gsub(name, "%.", "/")
+        local sError = ""
+        for pattern in string.gmatch(package.path, "[^;]+") do
+            local sPath = string.gsub(pattern, "%?", fname)
+            if sPath:sub(1, 1) ~= "/" then
+                sPath = fs.combine(dir, sPath)
+            end
+            if fs.exists(sPath) and not fs.isDir(sPath) then
+                local fnFile, sError = loadfile(sPath, nil, env)
+                if fnFile then
+                    return fnFile, sPath
+                else
+                    return nil, sError
+                end
+            else
+                if #sError > 0 then
+                    sError = sError .. "\n  "
+                end
+                sError = sError .. "no file '" .. sPath .. "'"
+            end
+        end
+        return nil, sError
+    end
+end
+
+local function make_require(package)
+    local sentinel = {}
+    return function(name)
+        expect(1, name, "string")
+
+        if package.loaded[name] == sentinel then
+            error("loop or previous error loading module '" .. name .. "'", 0)
+        end
+
+        if package.loaded[name] then
+            return package.loaded[name]
+        end
+
+        local sError = "module '" .. name .. "' not found:"
+        for _, searcher in ipairs(package.loaders) do
+            local loader = table.pack(searcher(name))
+            if loader[1] then
+                package.loaded[name] = sentinel
+                local result = loader[1](name, table.unpack(loader, 2, loader.n))
+                if result == nil then result = true end
+
+                package.loaded[name] = result
+                return result
+            else
+                sError = sError .. "\n  " .. loader[2]
+            end
+        end
+        error(sError, 2)
+    end
+end
+
+--- Build an implementation of Lua's @{package} library, and a @{require}
+-- function to load modules within it.
+--
+-- @tparam table env The environment to load packages into.
+-- @tparam string dir The directory that relative packages are loaded from.
+-- @treturn function The new @{require} function.
+-- @treturn table The new @{package} library.
+local function make_package(env, dir)
+    expect(1, env, "table")
+    expect(2, dir, "string")
+
+    local package = {}
+    package.loaded = {
+        _G = _G,
+        bit32 = bit32,
+        coroutine = coroutine,
+        math = math,
+        package = package,
+        string = string,
+        table = table,
+    }
+    package.path = "?;?.lua;?/init.lua;/rom/modules/main/?;/rom/modules/main/?.lua;/rom/modules/main/?/init.lua"
+    if turtle then
+        package.path = package.path .. ";/rom/modules/turtle/?;/rom/modules/turtle/?.lua;/rom/modules/turtle/?/init.lua"
+    elseif commands then
+        package.path = package.path .. ";/rom/modules/command/?;/rom/modules/command/?.lua;/rom/modules/command/?/init.lua"
+    end
+    package.config = "/\n;\n?\n!\n-"
+    package.preload = {}
+    package.loaders = { preload(package), from_file(package, env, dir) }
+
+    return make_require(package), package
+end
+
+return { make = make_package }

src/main/resources/assets/computercraft/lua/rom/modules/main/cc/shell/completion.lua

@@ -141,12 +141,12 @@ return {
     program = program,
 
     -- Re-export various other functions
-    help = wrap(help.completeTopic),
-    choice = wrap(completion.choice),
-    peripheral = wrap(completion.peripheral),
-    side = wrap(completion.side),
-    setting = wrap(completion.setting),
-    command = wrap(completion.command),
+    help = wrap(help.completeTopic), --- Wraps @{help.completeTopic} as a @{build} compatible function.
+    choice = wrap(completion.choice), --- Wraps @{cc.completion.choice} as a @{build} compatible function.
+    peripheral = wrap(completion.peripheral), --- Wraps @{cc.completion.peripheral} as a @{build} compatible function.
+    side = wrap(completion.side), --- Wraps @{cc.completion.side} as a @{build} compatible function.
+    setting = wrap(completion.setting), --- Wraps @{cc.completion.setting} as a @{build} compatible function.
+    command = wrap(completion.command), --- Wraps @{cc.completion.command} as a @{build} compatible function.
 
     build = build,
 }

src/main/resources/assets/computercraft/lua/rom/programs/advanced/bg.lua

@@ -1,4 +1,3 @@
-
 if not shell.openTab then
     printError("Requires multishell")
     return

src/main/resources/assets/computercraft/lua/rom/programs/advanced/fg.lua

@@ -1,4 +1,3 @@
-
 if not shell.openTab then
     printError("Requires multishell")
     return

src/main/resources/assets/computercraft/lua/rom/programs/alias.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 if #tArgs > 2 then
     print("Usage: alias <alias> <program>")

src/main/resources/assets/computercraft/lua/rom/programs/apis.lua

@@ -1,4 +1,3 @@
-
 local tApis = {}
 for k, v in pairs(_G) do
     if type(k) == "string" and type(v) == "table" and k ~= "_G" then

src/main/resources/assets/computercraft/lua/rom/programs/cd.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 if #tArgs < 1 then
     print("Usage: cd <path>")

src/main/resources/assets/computercraft/lua/rom/programs/command/commands.lua

@@ -1,4 +1,3 @@
-
 if not commands then
     printError("Requires a Command Computer.")
     return

src/main/resources/assets/computercraft/lua/rom/programs/command/exec.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 if not commands then
     printError("Requires a Command Computer.")

src/main/resources/assets/computercraft/lua/rom/programs/copy.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 if #tArgs < 2 then
     print("Usage: cp <source> <destination>")

src/main/resources/assets/computercraft/lua/rom/programs/delete.lua

@@ -9,9 +9,18 @@ for i = 1, args.n do
     local files = fs.find(shell.resolve(args[i]))
     if #files > 0 then
         for _, file in ipairs(files) do
-            local ok, err = pcall(fs.delete, file)
-            if not ok then
-                printError((err:gsub("^pcall: ", "")))
+            if fs.isReadOnly(file) then
+                printError("Cannot delete read-only file /" .. file)
+            elseif fs.isDriveRoot(file) then
+                printError("Cannot delete mount /" .. file)
+                if fs.isDir(file) then
+                    print("To delete its contents run rm /" .. fs.combine(file, "*"))
+                end
+            else
+                local ok, err = pcall(fs.delete, file)
+                if not ok then
+                    printError((err:gsub("^pcall: ", "")))
+                end
             end
         end
     else

src/main/resources/assets/computercraft/lua/rom/programs/eject.lua

@@ -1,4 +1,3 @@
-
 -- Get arguments
 local tArgs = { ... }
 if #tArgs == 0 then

src/main/resources/assets/computercraft/lua/rom/programs/fun/adventure.lua

@@ -1,4 +1,3 @@
-
 local tBiomes = {
     "in a forest",
     "in a pine forest",

src/main/resources/assets/computercraft/lua/rom/programs/fun/worm.lua

@@ -1,4 +1,3 @@
-
 -- Display the start screen
 local w, h = term.getSize()
 

src/main/resources/assets/computercraft/lua/rom/programs/gps.lua

@@ -1,4 +1,3 @@
-
 local function printUsage()
     print("Usages:")
     print("gps host")

src/main/resources/assets/computercraft/lua/rom/programs/http/pastebin.lua

@@ -1,4 +1,3 @@
-
 local function printUsage()
     print("Usages:")
     print("pastebin put <filename>")

src/main/resources/assets/computercraft/lua/rom/programs/http/wget.lua

@@ -1,4 +1,3 @@
-
 local function printUsage()
     print("Usage:")
     print("wget <url> [filename]")

src/main/resources/assets/computercraft/lua/rom/programs/id.lua

@@ -1,4 +1,3 @@
-
 local sDrive = nil
 local tArgs = { ... }
 if #tArgs > 0 then

src/main/resources/assets/computercraft/lua/rom/programs/label.lua

@@ -1,4 +1,3 @@
-
 local function printUsage()
     print("Usages:")
     print("label get")

src/main/resources/assets/computercraft/lua/rom/programs/list.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 
 -- Get all the files in the directory

src/main/resources/assets/computercraft/lua/rom/programs/lua.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 if #tArgs > 0 then
     print("This is an interactive Lua prompt.")
@@ -67,6 +66,13 @@ while bRunning do
     if s:match("%S") and tCommandHistory[#tCommandHistory] ~= s then
         table.insert(tCommandHistory, s)
     end
+    if settings.get("lua.warn_against_use_of_local") and s:match("^%s*local%s+") then
+        if term.isColour() then
+            term.setTextColour(colours.yellow)
+        end
+       print("To access local variables in later inputs, remove the local keyword.")
+       term.setTextColour(colours.white)
+    end
 
     local nForcePrint = 0
     local func, e = load(s, "=lua", "t", tEnv)
@@ -89,7 +95,10 @@ while bRunning do
             local n = 1
             while n < tResults.n or n <= nForcePrint do
                 local value = tResults[n + 1]
-                local ok, serialised = pcall(pretty.pretty, value)
+                local ok, serialised = pcall(pretty.pretty, value, {
+                    function_args = settings.get("lua.function_args"),
+                    function_source = settings.get("lua.function_source"),
+                })
                 if ok then
                     pretty.print(serialised)
                 else

src/main/resources/assets/computercraft/lua/rom/programs/monitor.lua

@@ -28,7 +28,7 @@ local monitor = peripheral.wrap(sName)
 local previousTerm = term.redirect(monitor)
 
 local co = coroutine.create(function()
-    shell.run(sProgram, table.unpack(tArgs, 3))
+    (shell.execute or shell.run)(sProgram, table.unpack(tArgs, 3))
 end)
 
 local function resume(...)

src/main/resources/assets/computercraft/lua/rom/programs/move.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 if #tArgs < 2 then
     print("Usage: mv <source> <destination>")
@@ -8,12 +7,35 @@ end
 local sSource = shell.resolve(tArgs[1])
 local sDest = shell.resolve(tArgs[2])
 local tFiles = fs.find(sSource)
+
+local function sanity_checks(source, dest)
+    if fs.exists(dest) then
+        printError("Destination exists")
+        return false
+    elseif fs.isReadOnly(dest) then
+        printError("Destination is read-only")
+        return false
+    elseif fs.isDriveRoot(source) then
+        printError("Cannot move mount /" .. source)
+        return false
+    elseif fs.isReadOnly(source) then
+        printError("Cannot move read-only file /" .. source)
+        return false
+    end
+    return true
+end
+
 if #tFiles > 0 then
     for _, sFile in ipairs(tFiles) do
         if fs.isDir(sDest) then
-            fs.move(sFile, fs.combine(sDest, fs.getName(sFile)))
+            local dest = fs.combine(sDest, fs.getName(sFile))
+            if sanity_checks(sFile, dest) then
+                fs.move(sFile, dest)
+            end
         elseif #tFiles == 1 then
-            fs.move(sFile, sDest)
+            if sanity_checks(sFile, sDest) then
+                fs.move(sFile, sDest)
+            end
         else
             printError("Cannot overwrite file multiple times")
             return

src/main/resources/assets/computercraft/lua/rom/programs/programs.lua

@@ -1,4 +1,3 @@
-
 local bAll = false
 local tArgs = { ... }
 if #tArgs > 0 and tArgs[1] == "all" then

src/main/resources/assets/computercraft/lua/rom/programs/rednet/chat.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 
 local function printUsage()

src/main/resources/assets/computercraft/lua/rom/programs/rednet/repeat.lua

@@ -1,4 +1,3 @@
-
 -- Find modems
 local tModems = {}
 for _, sModem in ipairs(peripheral.getNames()) do

src/main/resources/assets/computercraft/lua/rom/programs/redstone.lua

@@ -1,4 +1,3 @@
-
 local tArgs = { ... }
 
 local function printUsage()

src/main/resources/assets/computercraft/lua/rom/programs/rename.lua

@@ -10,6 +10,12 @@ local sDest = shell.resolve(tArgs[2])
 if not fs.exists(sSource) then
     printError("No matching files")
     return
+elseif fs.isDriveRoot(sSource) then
+    printError("Can't rename mounts")
+    return
+elseif fs.isReadOnly(sSource) then
+    printError("Source is read-only")
+    return
 elseif fs.exists(sDest) then
     printError("Destination exists")
     return

src/main/resources/assets/computercraft/lua/rom/programs/shell.lua

@@ -11,6 +11,7 @@
 -- @module[module] shell
 
 local expect = dofile("rom/modules/main/cc/expect.lua").expect
+local make_package = dofile("rom/modules/main/cc/require.lua").make
 
 local multishell = multishell
 local parentShell = shell
@@ -28,94 +29,10 @@ local tCompletionInfo = parentShell and parentShell.getCompletionInfo() or {}
 local tProgramStack = {}
 
 local shell = {} --- @export
-local function createShellEnv(sDir)
-    local tEnv = {}
-    tEnv.shell = shell
-    tEnv.multishell = multishell
-
-    local package = {}
-    package.loaded = {
-        _G = _G,
-        bit32 = bit32,
-        coroutine = coroutine,
-        math = math,
-        package = package,
-        string = string,
-        table = table,
-    }
-    package.path = "?;?.lua;?/init.lua;/rom/modules/main/?;/rom/modules/main/?.lua;/rom/modules/main/?/init.lua"
-    if turtle then
-        package.path = package.path .. ";/rom/modules/turtle/?;/rom/modules/turtle/?.lua;/rom/modules/turtle/?/init.lua"
-    elseif command then
-        package.path = package.path .. ";/rom/modules/command/?;/rom/modules/command/?.lua;/rom/modules/command/?/init.lua"
-    end
-    package.config = "/\n;\n?\n!\n-"
-    package.preload = {}
-    package.loaders = {
-        function(name)
-            if package.preload[name] then
-                return package.preload[name]
-            else
-                return nil, "no field package.preload['" .. name .. "']"
-            end
-        end,
-        function(name)
-            local fname = string.gsub(name, "%.", "/")
-            local sError = ""
-            for pattern in string.gmatch(package.path, "[^;]+") do
-                local sPath = string.gsub(pattern, "%?", fname)
-                if sPath:sub(1, 1) ~= "/" then
-                    sPath = fs.combine(sDir, sPath)
-                end
-                if fs.exists(sPath) and not fs.isDir(sPath) then
-                    local fnFile, sError = loadfile(sPath, nil, tEnv)
-                    if fnFile then
-                        return fnFile, sPath
-                    else
-                        return nil, sError
-                    end
-                else
-                    if #sError > 0 then
-                        sError = sError .. "\n  "
-                    end
-                    sError = sError .. "no file '" .. sPath .. "'"
-                end
-            end
-            return nil, sError
-        end,
-    }
-
-    local sentinel = {}
-    local function require(name)
-        expect(1, name, "string")
-        if package.loaded[name] == sentinel then
-            error("loop or previous error loading module '" .. name .. "'", 0)
-        end
-        if package.loaded[name] then
-            return package.loaded[name]
-        end
-
-        local sError = "module '" .. name .. "' not found:"
-        for _, searcher in ipairs(package.loaders) do
-            local loader = table.pack(searcher(name))
-            if loader[1] then
-                package.loaded[name] = sentinel
-                local result = loader[1](name, table.unpack(loader, 2, loader.n))
-                if result == nil then result = true end
-
-                package.loaded[name] = result
-                return result
-            else
-                sError = sError .. "\n  " .. loader[2]
-            end
-        end
-        error(sError, 2)
-    end
-
-    tEnv.package = package
-    tEnv.require = require
-
-    return tEnv
+local function createShellEnv(dir)
+    local env = { shell = shell, multishell = multishell }
+    env.require, env.package = make_package(env, dir)
+    return env
 end
 
 -- Colours
@@ -130,8 +47,25 @@ else
     bgColour = colours.black
 end
 
-local function run(_sCommand, ...)
-    local sPath = shell.resolveProgram(_sCommand)
+--- Run a program with the supplied arguments.
+--
+-- Unlike @{shell.run}, each argument is passed to the program verbatim. While
+-- `shell.run("echo", "b c")` runs `echo` with `b` and `c`,
+-- `shell.execute("echo", "b c")` runs `echo` with a single argument `b c`.
+--
+-- @tparam string command The program to execute.
+-- @tparam string ... Arguments to this program.
+-- @treturn boolean Whether the program exited successfully.
+-- @usage Run `paint my-image` from within your program:
+--
+--     shell.execute("paint", "my-image")
+function shell.execute(command, ...)
+    expect(1, command, "string")
+    for i = 1, select('#', ...) do
+        expect(i + 1, select(i, ...), "string")
+    end
+
+    local sPath = shell.resolveProgram(command)
     if sPath ~= nil then
         tProgramStack[#tProgramStack + 1] = sPath
         if multishell then
@@ -144,7 +78,7 @@ local function run(_sCommand, ...)
 
         local sDir = fs.getDir(sPath)
         local env = createShellEnv(sDir)
-        env.arg = { [0] = _sCommand, ... }
+        env.arg = { [0] = command, ... }
         local result = os.run(env, sPath, ...)
 
         tProgramStack[#tProgramStack] = nil
@@ -196,11 +130,12 @@ end
 -- @usage Run `paint my-image` from within your program:
 --
 --     shell.run("paint", "my-image")
+-- @see shell.execute Run a program directly without parsing the arguments.
 function shell.run(...)
     local tWords = tokenise(...)
     local sCommand = tWords[1]
     if sCommand then
-        return run(sCommand, table.unpack(tWords, 2))
+        return shell.execute(sCommand, table.unpack(tWords, 2))
     end
     return false
 end