FDC37B787-NS Standard Microsystems (SMSC), FDC37B787-NS Datasheet - Page 57

• Manufacturer Part Number: FDC37B787-NS
• Manufacturer: Standard Microsystems (SMSC)

Specifications of FDC37B787-NS

• Pin Count: 128
• Lead Free Status / RoHS Status: Compliant

The amount of data which can be handled with a
single command to the FDC depends upon MT
(multi-track) and N (number of bytes/sector).
The Multi-Track function (MT) allows the FDC to
read data from both sides of the diskette. For a
particular cylinder, data will be transferred starting
at Sector 1, Side 0 and completing the last sector
of the same track at Side 1.
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 24.
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.
MT
0
1
0
1
0
1
N
1
1
2
2
3
3
TABLE 24 - EFFECTS OF MT AND N BITS
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
MAXIMUM TRANSFER
CAPACITY
57
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
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 25
describes the effect of the SK bit on the Read
Data command execution and results. Except
where noted in Table 25, the C or R value of the
sector address is automatically incremented.
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
FINAL SECTOR READ
FROM DISK
"01" indicating