LPC47B37X View Datasheet(PDF) - SMSC -> Microchip
Part Name
Description
MFG CO.
LPC47B37X
SMSC -> Microchip
'LPC47B37X' PDF : 254 Pages View PDF
If the host terminates a read or write operation in the FDC, the ID information in the result phase is
dependent upon the state of the MT bit and EOT byte. Refer to Table 19.
At the completion of the Read Data command, the head is not unloaded until after the Head Unload Time
Interval (specified in the Specify command) has elapsed. If the host issues another command before the
head unloads, then the head settling time may be saved between subsequent reads.
If the FDC detects a pulse on the nINDEX pin twice without finding the specified sector (meaning that the
diskette's index hole passes through index detect logic in the drive twice), the FDC sets the IC code in
Status 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.
After reading the ID and Data Fields in each 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 21 describes the effect of
the SK bit on the Read Data command execution and results. Except where noted in Table 20, the C or R
value of the sector address is automatically incremented (see Table 22).
Table 19 - Effects of MT and N Bits
MAXIMUM TRANSFER FINAL SECTOR READ
MT N
CAPACITY
FROM DISK
0 1 256 x 26 = 6,656
26 at side 0 or 1
1 1 256 x 52 = 13,312
26 at side 1
0 2 512 x 15 = 7,680
15 at side 0 or 1
1 2 512 x 30 = 15,360
15 at side 1
0 3 1024 x 8 = 8,192
8 at side 0 or 1
1 3 1024 x 16 = 16,384
16 at side 1
SK BIT
VALUE
0
0
1
1
Table 20 - Skip Bit vs Read Data Command
DATA ADDRESS
MARK TYPE
RESULTS
ENCOUNTERED
SECTOR CM BIT OF DESCRIPTION OF
READ? ST2 SET?
RESULTS
Normal Data
Yes
No
Normal
termination.
Deleted Data
Yes
Yes
Address not
incremented. Next
sector not
searched for.
Normal Data
Yes
No
Normal
termination.
Deleted Data
No
Yes
Normal
termination.
Sector not read
("skipped").
56
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