diff --git a/history/feed.go b/history/feed.go
index b3a0bd4..3b05ede 100644
--- a/history/feed.go
+++ b/history/feed.go
@@ -1,7 +1,9 @@
 package history
 
 import (
+	"errors"
 	"fmt"
+	"net/url"
 	"strings"
 	"time"
 
@@ -10,9 +12,7 @@ import (
 	"github.com/gorilla/feeds"
 )
 
-var groupPeriod, _ = time.ParseDuration("30m")
-
-func recentChangesFeed() *feeds.Feed {
+func recentChangesFeed(opts FeedOptions) *feeds.Feed {
 	feed := &feeds.Feed{
 		Title:       "Recent changes",
 		Link:        &feeds.Link{Href: cfg.URL},
@@ -21,46 +21,101 @@ func recentChangesFeed() *feeds.Feed {
 		Updated:     time.Now(),
 	}
 	revs := RecentChanges(30)
-	groups := groupRevisionsByPeriod(revs, groupPeriod)
+	groups := opts.grouping.Group(revs)
 	for _, grp := range groups {
-		item := grp.feedItem()
+		item := grp.feedItem(opts)
 		feed.Add(&item)
 	}
 	return feed
 }
 
 // RecentChangesRSS creates recent changes feed in RSS format.
-func RecentChangesRSS() (string, error) {
-	return recentChangesFeed().ToRss()
+func RecentChangesRSS(opts FeedOptions) (string, error) {
+	return recentChangesFeed(opts).ToRss()
 }
 
 // RecentChangesAtom creates recent changes feed in Atom format.
-func RecentChangesAtom() (string, error) {
-	return recentChangesFeed().ToAtom()
+func RecentChangesAtom(opts FeedOptions) (string, error) {
+	return recentChangesFeed(opts).ToAtom()
 }
 
 // RecentChangesJSON creates recent changes feed in JSON format.
-func RecentChangesJSON() (string, error) {
-	return recentChangesFeed().ToJSON()
+func RecentChangesJSON(opts FeedOptions) (string, error) {
+	return recentChangesFeed(opts).ToJSON()
 }
 
-func (grp revisionGroup) feedItem() feeds.Item {
+type revisionGroup []Revision
+
+func newRevisionGroup(rev Revision) revisionGroup {
+	return revisionGroup([]Revision{rev})
+}
+
+func (grp *revisionGroup) addRevision(rev Revision) {
+	*grp = append(*grp, rev)
+}
+
+func groupRevisionsByMonth(revs []Revision) (res []revisionGroup) {
+	var (
+		currentYear  int
+		currentMonth time.Month
+	)
+	for _, rev := range revs {
+		if rev.Time.Month() != currentMonth || rev.Time.Year() != currentYear {
+			currentYear = rev.Time.Year()
+			currentMonth = rev.Time.Month()
+			res = append(res, newRevisionGroup(rev))
+		} else {
+			res[len(res)-1].addRevision(rev)
+		}
+	}
+	return res
+}
+
+// groupRevisionsByPeriodFromNow groups close-together revisions.
+// If two revisions happened within period of each other, they are put in the same group.
+func groupRevisionsByPeriod(revs []Revision, period time.Duration) (res []revisionGroup) {
+	if len(revs) == 0 {
+		return res
+	}
+
+	currTime := revs[0].Time
+	res = append(res, newRevisionGroup(revs[0]))
+	for _, rev := range revs[1:] {
+		if currTime.Sub(rev.Time) < period {
+			res[len(res)-1].addRevision(rev)
+		} else {
+			res = append(res, newRevisionGroup(rev))
+		}
+		currTime = rev.Time
+	}
+	return res
+}
+
+func (grp revisionGroup) feedItem(opts FeedOptions) feeds.Item {
 	return feeds.Item{
-		Title:       grp.title(),
+		Title:       grp.title(opts.groupOrder),
 		Author:      grp.author(),
-		Id:          grp[0].Hash,
-		Description: grp.descriptionForFeed(),
+		Id:          grp[len(grp)-1].Hash,
+		Description: grp.descriptionForFeed(opts.groupOrder),
 		Created:     grp[len(grp)-1].Time, // earliest revision
 		Updated:     grp[0].Time,          // latest revision
 		Link:        &feeds.Link{Href: cfg.URL + grp[0].bestLink()},
 	}
 }
 
-func (grp revisionGroup) title() string {
+func (grp revisionGroup) title(order FeedGroupOrder) string {
+	var message string
+	switch order {
+	case NewToOld:
+		message = grp[0].Message
+	case OldToNew:
+		message = grp[len(grp)-1].Message
+	}
+
 	if len(grp) == 1 {
-		return grp[0].Message
+		return message
 	} else {
-		return fmt.Sprintf("%d edits (%s, ...)", len(grp), grp[0].Message)
+		return fmt.Sprintf("%d edits (%s, ...)", len(grp), message)
 	}
 }
 
@@ -75,10 +130,85 @@ func (grp revisionGroup) author() *feeds.Author {
 	return &feeds.Author{Name: author}
 }
 
-func (grp revisionGroup) descriptionForFeed() string {
+func (grp revisionGroup) descriptionForFeed(order FeedGroupOrder) string {
 	builder := strings.Builder{}
-	for _, rev := range grp {
-		builder.WriteString(rev.descriptionForFeed())
+	switch order {
+	case NewToOld:
+		for _, rev := range grp {
+			builder.WriteString(rev.descriptionForFeed())
+		}
+	case OldToNew:
+		for i := len(grp) - 1; i >= 0; i-- {
+			builder.WriteString(grp[i].descriptionForFeed())
+		}
 	}
 	return builder.String()
 }
+
+type FeedOptions struct {
+	grouping   FeedGrouping
+	groupOrder FeedGroupOrder
+}
+
+func ParseFeedOptions(query url.Values) (FeedOptions, error) {
+	grouping, err := parseFeedGrouping(query)
+	if err != nil {
+		return FeedOptions{}, err
+	}
+	groupOrder, err := parseFeedGroupOrder(query)
+	if err != nil {
+		return FeedOptions{}, err
+	}
+	return FeedOptions{grouping, groupOrder}, nil
+}
+
+type FeedGrouping interface {
+	Group([]Revision) []revisionGroup
+}
+
+func parseFeedGrouping(query url.Values) (FeedGrouping, error) {
+	if query.Get("period") == "" {
+		return NormalFeedGrouping{}, nil
+	} else {
+		period, err := time.ParseDuration(query.Get("period"))
+		if err != nil {
+			return nil, err
+		}
+		return PeriodFeedGrouping{Period: period}, nil
+	}
+}
+
+type NormalFeedGrouping struct{}
+
+func (NormalFeedGrouping) Group(revs []Revision) (res []revisionGroup) {
+	for _, rev := range revs {
+		res = append(res, newRevisionGroup(rev))
+	}
+	return res
+}
+
+type PeriodFeedGrouping struct {
+	Period time.Duration
+}
+
+func (g PeriodFeedGrouping) Group(revs []Revision) (res []revisionGroup) {
+	return groupRevisionsByPeriod(revs, g.Period)
+}
+
+type FeedGroupOrder int
+
+const (
+	NewToOld FeedGroupOrder = iota
+	OldToNew FeedGroupOrder = iota
+)
+
+func parseFeedGroupOrder(query url.Values) (FeedGroupOrder, error) {
+	switch query.Get("order") {
+	case "oldtonew":
+		return OldToNew, nil
+	case "newtoold":
+	case "":
+		return NewToOld, nil
+	}
+	return 0, errors.New("unknown order")
+}
diff --git a/history/revision.go b/history/revision.go
index fd41849..b01d79b 100644
--- a/history/revision.go
+++ b/history/revision.go
@@ -209,47 +209,3 @@ func PrimitiveDiffAtRevision(filepath, hash string) (string, error) {
 	}
 	return out.String(), err
 }
-
-type revisionGroup []Revision
-
-func newRevisionGroup(rev Revision) revisionGroup {
-	return revisionGroup([]Revision{rev})
-}
-
-func (grp *revisionGroup) addRevision(rev Revision) {
-	*grp = append(*grp, rev)
-}
-
-func groupRevisionsByMonth(revs []Revision) (res []revisionGroup) {
-	var (
-		currentYear  int
-		currentMonth time.Month
-	)
-	for _, rev := range revs {
-		if rev.Time.Month() != currentMonth || rev.Time.Year() != currentYear {
-			currentYear = rev.Time.Year()
-			currentMonth = rev.Time.Month()
-			res = append(res, newRevisionGroup(rev))
-		} else {
-			res[len(res)-1].addRevision(rev)
-		}
-	}
-	return res
-}
-
-// groupRevisionsByPeriod groups revisions by how long ago they were.
-// Revisions less than one period ago are placed in one group, revisions between one and two periods are in another, and so on.
-func groupRevisionsByPeriod(revs []Revision, period time.Duration) (res []revisionGroup) {
-	now := time.Now()
-	currentPeriod := -1
-	for _, rev := range revs {
-		newPeriod := int(now.Sub(rev.Time).Seconds() / period.Seconds())
-		if newPeriod != currentPeriod {
-			currentPeriod = newPeriod
-			res = append(res, newRevisionGroup(rev))
-		} else {
-			res[len(res)-1].addRevision(rev)
-		}
-	}
-	return res
-}
diff --git a/history/view.qtpl b/history/view.qtpl
index b4ec298..2a87825 100644
--- a/history/view.qtpl
+++ b/history/view.qtpl
@@ -8,7 +8,7 @@ HyphaeLinksHTML returns a comma-separated list of hyphae that were affected by t
 		{% if i > 0 %}
 			<span aria-hidden="true">, </span>
 		{% endif %}
-		<a href="/hypha/{%s hyphaName %}">{%s hyphaName %}</a>
+		<a href="/primitive-diff/{%s rev.Hash %}/{%s hyphaName %}">{%s hyphaName %}</a>
 	{% endfor %}
 {% endstripspace %}
 {% endfunc %}
diff --git a/history/view.qtpl.go b/history/view.qtpl.go
index be51e18..65c5a71 100644
--- a/history/view.qtpl.go
+++ b/history/view.qtpl.go
@@ -39,7 +39,11 @@ func (rev Revision) StreamHyphaeLinksHTML(qw422016 *qt422016.Writer) {
 //line history/view.qtpl:10
 		}
 //line history/view.qtpl:10
-		qw422016.N().S(`<a href="/hypha/`)
+		qw422016.N().S(`<a href="/primitive-diff/`)
+//line history/view.qtpl:11
+		qw422016.E().S(rev.Hash)
+//line history/view.qtpl:11
+		qw422016.N().S(`/`)
 //line history/view.qtpl:11
 		qw422016.E().S(hyphaName)
 //line history/view.qtpl:11
diff --git a/web/history.go b/web/history.go
index 595d19f..9c84b28 100644
--- a/web/history.go
+++ b/web/history.go
@@ -61,8 +61,14 @@ func handlerRecentChanges(w http.ResponseWriter, rq *http.Request) {
 }
 
 // genericHandlerOfFeeds is a helper function for the web feed handlers.
-func genericHandlerOfFeeds(w http.ResponseWriter, rq *http.Request, f func() (string, error), name string, contentType string) {
-	if content, err := f(); err != nil {
+func genericHandlerOfFeeds(w http.ResponseWriter, rq *http.Request, f func(history.FeedOptions) (string, error), name string, contentType string) {
+	opts, err := history.ParseFeedOptions(rq.URL.Query())
+	var content string
+	if err == nil {
+		content, err = f(opts)
+	}
+
+	if err != nil {
 		w.Header().Set("Content-Type", "text/plain;charset=utf-8")
 		w.WriteHeader(http.StatusInternalServerError)
 		fmt.Fprint(w, "An error while generating "+name+": "+err.Error())