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).
57