diff --git a/atrcopy/ataridos.py b/atrcopy/ataridos.py
index 1681def..ec2db9a 100644
--- a/atrcopy/ataridos.py
+++ b/atrcopy/ataridos.py
@@ -578,10 +578,22 @@ class AtariDosDiskImage(DiskImageBase):
         start, count = self.get_contiguous_sectors(self.first_vtoc, self.num_vtoc)
         segment = RawSectorsSegment(r[start:start+count], self.first_vtoc, self.num_vtoc, count, 128, 3, self.header.sector_size, name="VTOC")
         segment.style[:] = get_style_bits(data=True)
+        segment.set_comment_at(0x00, "Type code")
+        segment.set_comment_at(0x01, "Total number of sectors")
+        segment.set_comment_at(0x03, "Number of free sectors")
+        segment.set_comment_at(0x05, "reserved")
+        segment.set_comment_at(0x06, "unused")
+        segment.set_comment_at(0x0a, "Sector bit map")
+        segment.set_comment_at(0x64, "unused")
         segments.append(segment)
         if self.vtoc2 > 0:
             start, count = self.get_contiguous_sectors(self.vtoc2, 1)
             segment = RawSectorsSegment(r[start:start+count], self.vtoc2, 1, count, 128, 3, self.header.sector_size, name="VTOC2")
+            segment.style[:] = get_style_bits(data=True)
+            segment.set_comment_at(0x00, "Repeat of sectors 48-719")
+            segment.set_comment_at(0x44, "Sector bit map 720-1023")
+            segment.set_comment_at(0x7a, "Number of free sectors above 720")
+            segment.set_comment_at(0x7c, "unused")
             segments.append(segment)
         return segments
     
@@ -592,6 +604,14 @@ class AtariDosDiskImage(DiskImageBase):
         start, count = self.get_contiguous_sectors(361, 8)
         segment = RawSectorsSegment(r[start:start+count], 361, 8, count, 128, 3, self.header.sector_size, name="Directory")
         segment.style[:] = get_style_bits(data=True)
+        index = 0
+        for filenum in range(64):
+            segment.set_comment_at(index + 0x00, "FILE #%d: Flag" % filenum)
+            segment.set_comment_at(index + 0x01, "FILE #%d: Number of sectors in file" % filenum)
+            segment.set_comment_at(index + 0x03, "FILE #%d: Starting sector number" % filenum)
+            segment.set_comment_at(index + 0x05, "FILE #%d: Filename" % filenum)
+            segment.set_comment_at(index + 0x0d, "FILE #%d: Extension" % filenum)
+            index += 16
         segments.append(segment)
         return segments
     
diff --git a/atrcopy/dos33.py b/atrcopy/dos33.py
index 0e48dae..482df40 100644
--- a/atrcopy/dos33.py
+++ b/atrcopy/dos33.py
@@ -496,6 +496,25 @@ class Dos33DiskImage(DiskImageBase):
         start, count = self.get_contiguous_sectors(self.header.first_vtoc, 1)
         segment = RawTrackSectorSegment(r[start:start+count], self.header.first_vtoc, 1, count, 0, 0, self.header.sector_size, name="VTOC")
         segment.style[:] = get_style_bits(data=True)
+        segment.set_comment_at(0x00, "unused")
+        segment.set_comment_at(0x01, "Track number of next catalog sector")
+        segment.set_comment_at(0x02, "Sector number of next catalog sector")
+        segment.set_comment_at(0x03, "Release number of DOS used to format")
+        segment.set_comment_at(0x04, "unused")
+        segment.set_comment_at(0x06, "Volume number")
+        segment.set_comment_at(0x07, "unused")
+        segment.set_comment_at(0x27, "Number of track/sector pairs per t/s list sector")
+        segment.set_comment_at(0x28, "unused")
+        segment.set_comment_at(0x30, "Last track that sectors allocated")
+        segment.set_comment_at(0x31, "Track allocation direction")
+        segment.set_comment_at(0x32, "unused")
+        segment.set_comment_at(0x34, "Tracks per disk")
+        segment.set_comment_at(0x35, "Sectors per track")
+        segment.set_comment_at(0x36, "Bytes per sector")
+        index = 0x38
+        for track in range(35):
+            segment.set_comment_at(index, "Free sectors in track %d" % track)
+            index += 4
         segments.append(segment)
         return segments
     
@@ -513,6 +532,22 @@ class Dos33DiskImage(DiskImageBase):
         raw = self.rawdata.get_indexed(byte_order)
         segment = DefaultSegment(raw, name="Catalog")
         segment.style[:] = get_style_bits(data=True)
+        index = 0
+        filenum = 0
+        while index < len(segment):
+            segment.set_comment_at(index + 0x00, "unused")
+            segment.set_comment_at(index + 0x01, "Track number of next catalog sector")
+            segment.set_comment_at(index + 0x02, "Sector number of next catalog sector")
+            segment.set_comment_at(index + 0x03, "unused")
+            index += 0x0b
+            for i in range(7):
+                segment.set_comment_at(index + 0x00, "FILE #%d: Track number of next catalog sector" % filenum)
+                segment.set_comment_at(index + 0x01, "FILE #%d: Sector number of next catalog sector" % filenum)
+                segment.set_comment_at(index + 0x02, "FILE #%d: File type" % filenum)
+                segment.set_comment_at(index + 0x03, "FILE #%d: Filename" % filenum)
+                segment.set_comment_at(index + 0x21, "FILE #%d: Number of sectors in file" % filenum)
+                index += 0x23
+                filenum += 1
         segments.append(segment)
         return segments
 
diff --git a/atrcopy/segments.py b/atrcopy/segments.py
index cd7bbc0..992f8dd 100644
--- a/atrcopy/segments.py
+++ b/atrcopy/segments.py
@@ -804,11 +804,14 @@ class DefaultSegment(object):
             comments.append(comment)
         return has_comments, comments
 
+    def set_comment_at(self, index, text):
+        rawindex = self.get_raw_index(index)
+        self.rawdata.extra.comments[rawindex] = text
+
     def set_comment(self, ranges, text):
         self.set_style_ranges(ranges, comment=True)
         for start, end in ranges:
-            rawindex = self.get_raw_index(start)
-            self.rawdata.extra.comments[rawindex] = text
+            self.set_comment_at(start, text)
     
     def get_comment(self, index):
         rawindex = self.get_raw_index(index)