Register 0 to "01" indicating abnormal termination, sets
the ND bit in Status Register 1 to "1" indicating a sector
not found, and terminates the Read Data Command.
sector, the FDC checks the CRC bytes. If a CRC error
occurs in the ID or data field, the FDC sets the IC code in
Status Register 0 to "01" indicating abnormal termination,
sets the DE bit flag in Status Register 1 to "1", sets the
DD bit in Status Register 2 to "1" if CRC is incorrect in the
ID field, and terminates the Read Data Command. Table
22 describes the effect of the SK bit on the Read Data
command execution and results. Except where noted in
Table 22, the C or R value of the sector address is
automatically incremented (see Table 24).
After reading the ID and Data Fields in each
Table 21 - Effects of MT and N Bits
MAXIMUM TRANSFER
FINAL SECTOR READ
FROM DISK
CAPACITY
MT
N
0
1
0
1
0
1
1
1
2
2
3
3
256 x 26 = 6,656
256 x 52 = 13,312
512 x 15 = 7,680
512 x 30 = 15,360
1024 x 8 = 8,192
1024 x 16 = 16,384
26 at side 0 or 1
26 at side 1
15 at side 0 or 1
15 at side 1
8 at side 0 or 1
16 at side 1
Table 22 - Skip Bit vs Read Data Command
DATA ADDRESS
MARK TYPE
ENCOUNTERED
SK BIT
VALUE
RESULTS
SECTOR CM BIT OF DESCRIPTION OF
READ?
ST2 SET?
RESULTS
0
0
Normal Data
Deleted Data
Yes
No
Normal
termination.
Address not
incremented. Next
sector not
Yes
Yes
searched for.
Normal
termination.
Normal
1
1
Normal Data
Deleted Data
Yes
No
No
Yes
termination. Sector
not read
("skipped").
57
SMSC [ SMSC CORPORATION ]
