Commodore VIC-20 User Manual page 275

Chapter 8: Peripheral Devices
261
Look at Figure 8-2. You will see that the tracks on the diskette are not
all the same length. The ones nearest the outer edge of the diskette are longer
than the ones near the center. To make the most of the space available on the
diskette, the 1540 Disk Drive puts more sectors into each of the outer tracks.
The number of sectors per track varies from 17 on the inner tracks to 21 in
the outer tracks. This means that one 1540 diskette can hold 176,640 bytes.
Tracks
1-17 (21
sectors/track)
L----.. Tracks
18-24 (19
sectors/track)
L------Tracks
25-30 (18
sectors/track)
L------Tracks
31-35 (17
sectors/track)
FIGURl8.2. 1540 Diskette sectoring pattern
(by
tracks)