/
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NOTE
'\,
Not
to
scale
"-
"-
POINTER TO LINK
"-
~~~~H:~~L
BLOCKS "
Note: Tracks 36 to 70 refer to double-sided disks readable in
1571
mode.
SYNC I
08
CHECKSUM
SECTOR
TRACK
101,102
GAPI
SYNC 2
07
BYTEO, BYTEI
DATA
CHECKSUM 2
GAP 2
Figure
C·l.
GCR·Formatted Diskette
- 40 bits
of
ones (all I 's
is
the highest write frequency).
- Disk I.D. field identification mark.
- Checksum
of
101,102,
SECTOR, TRACK.
- The number
of
this sector
- Track which this sector resides on.
- 2 bytes (20 bits) indicating the diskette I.D. (the I.D.
is
specified
by
the user when the diskette
is
formatted).
- 72 bits
of
GCRO
or 01010101
(8
bit byte x 9)
- 40 bits
of
ones.
- Disk data field identification mark.
- Track and sector
of
next related block.
- 254 bytes (2540 bits)
of
data.
- Checksum
of
BYTEO,
BYTEI,
and DATA.
- Variable gap
of
OCR
O.
This gap
is
variable depending on the
speed
of
the disk during format. OAP 2 will be constant for all
sectors except for the tail gap (the gap between first and the
last sectors).
104
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