pc8477b National Semiconductor Corporation, pc8477b Datasheet - Page 16

• Manufacturer Part Number: pc8477b
• Description: Advanced Floppy Disk Controller
• Manufacturer: National Semiconductor Corporation

4 0 Command Set Description
READ DATA
Command Phase
Execution Phase Data read from disk drive is transferred
to system via DMA or Non-DMA modes
Result Phase
READ DELETED DATA
Command Phase
Execution Phase Data read from disk drive is transferred
to system via DMA or Non-DMA modes
Result Phase
READ ID
Command Phase
Execution Phase Controller reads first ID Field header
bytes it can find and reports these bytes to the system in the
result bytes
IPS
IPS
MT
MT
0
X
MFM
MFM
MFM
X
X
X
End of Track Sector Number
End of Track Sector Number
X
0
Intersector Gap Length
Intersector Gap Length
SK
SK
X
X
Drive Head Number
Drive Head Number
Status Register 0
Status Register 1
Status Register 2
Status Register 0
Status Register 1
Status Register 2
Bytes per Sector
Bytes per Sector
Bytes per Sector
Bytes per Sector
Sector Number
Sector Number
Sector Number
Sector Number
Track Number
Track Number
Track Number
Track Number
Head Number
Head Number
Data Length
Data Length
X
0
0
X
0
X
1
X
0
X
1
X
HD
0
HD
HD
1
1
DR1
DR1
DR1
1
1
0
(Continued)
DR0
DR0
DR0
0
0
0
16
Result Phase
READ A TRACK
Command Phase
Execution Phase Data read from disk drive is transferred
to system via DMA or Non-DMA modes
Result Phase
RECALIBRATE
Command Phase
Execution Phase Disk drive head is stepped out to
Track 0
No Result Phase
RELATIVE SEEK
Command Phase
Execution Phase Disk drive head stepped in or out a
programmable number of tracks
No Result Phase
IPS
1
X
0
0
0
DIR
0
0
X
MFM
X
End of Track Sector Number
0
0
0
X
Intersector Gap Length
Relative Track Number
X
0
Drive Head Number
Status Register 0
Status Register 1
Status Register 2
Status Register 0
Status Register 1
Status Register 2
Bytes per Sector
Bytes per Sector
Bytes per Sector
Sector Number
Sector Number
Sector Number
Track Number
Track Number
Track Number
0
0
Head Number
Head Number
X
0
Data Length
X
0
0
0
X
1
0
X
HD
1
0
HD
1
0
DR1
DR1
DR1
1
1
1
DR0
DR0
DR0
1
1
0