PHASE
Command
PERPENDICULAR MODE
DATA BUS
R/W D7 D6 D5 D4 D3 D2 D1
D0
REMARKS
W
0 00100
1
0 Command Codes
OW 0 D3 D2 D1 D0 GAP WGATE
PHASE
Command
Result
INVALID CODES
DATA BUS
R/W D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
W
----- Invalid Codes -----
Invalid Command Codes
(NoOp - FDC goes into
Standby State)
R
------- ST0 -------
ST0 = 80H
PHASE
Command
Result
LOCK
DATA BUS
R/W
D7
D6 D5
D4
D3 D2 D1 D0
REMARKS
W LOCK 0 0
1
0 1 0 0 Command Codes
R
0
0 0 LOCK 0 0 0 0
SC is returned if the last command that was issued was the Format command. EOT is returned if the
last command was a Read or Write.
Note: These bits are used internally only. They are not reflected in the Drive Select pins. It is the
user's responsibility to maintain correspondence between these bits and the Drive Select pins (DOR).
50