PC87303VUL Datasheet, PDF (53/114 Pages) National Semiconductor (TI) – PC87303VUL SuperI/OTM Sidewinder Lite Floppy Disk Controller, Keyboard Controller, Real-Time Clock, Dual UARTs, IEEE 1284 Parallel Port, and IDE Inter

4 0 FDC Command Set Description (Continued)
RELATIVE SEEK
Result Phase
Command Phase
1
DIR
0
0
1
1
1
1
X
X
X
X
X
HD
DR1
DR0
Execution Phase Disk drive head stepped in or out a pro-
grammable number of tracks
Result Phase None
SCAN EQUAL
Command Phase
MT MFM SK 1 0
0
0
1
IPS
X
X
X X HD DR1 DR0
Track Number
Drive Head Number
Sector Number
Bytes per Sector
End of Track Sector Number
Intersector Gap Length
Sector Step Size
Execution Phase Data transferred from system to control-
ler is compared to data read from disk
Result Phase
MT MFM SK 1 1
1
0
1
IPS
X
X
X X HD DR1 DR0
Status Register 0
Status Register 1
Status Register 2
Track Number
Head Number
Sector Number
Bytes per Sector
SCAN HIGH OR EQUAL
Status Register 0
Status Register 1
Status Register 2
Track Number
Head Number
Sector Number
Bytes per Sector
SCAN LOW OR EQUAL
Command Phase
MT MFM SK 1 1
0
0
1
IPS
X
X
X X HD DR1 DR0
Track Number
Drive Head Number
Sector Number
Bytes per Sector
End of Track Sector Number
Intersector Gap Length
Sector Step Size
Execution Phase Data transferred from system to control-
ler is compared to data read from disk
Result Phase
Status Register 0
Status Register 1
Status Register 2
Track Number
Head Number
Sector Number
Bytes per Sector
SEEK
Command Phase
Command Phase
MT MFM SK 1 1
1
0
IPS
X
X
X X HD DR1
Track Number
Drive Head Number
Sector Number
Bytes per Sector
End of Track Sector Number
Intersector Gap Length
Sector Step Size
1
DR0
0
0
0
0
1
1
X
X
X
X
X
HD
New Track Number
MSN of Track Number
0
0
1
DR1
1
DR0
0
0
Note The last Command Phase byte is required only if ETR is set in Mode
Command
Execution Phase Disk drive head is stepped in or out to a
programmed track
Result Phase None
Execution Phase Data transferred from system to control-
ler is compared to data read from disk
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