IBM 5150 Hardware Reference Manual page 118

Command Summary (continued)
DATA BUS
PHASE RIW
07 06
05 04
03
02
01
DO
REMARKS
SCAN HIGH OR EQUAL
Command W MT
MF SK 1 1 1 0 1 Command Codes
W X X X X
X HD US1
usa
w
C Sector 10 information
W
H prior to command
W
R execution
W
N
W
EDT
W
GPL
W
STP
Execution
Data compared between
the FDD and main-system
Result R
ST 0 Status information after
R
ST 1 command execution
R
ST 2
R
C
Sector 10 information
R
H after command execution
R
R
R
N
RECALIBRATE
Command W
0
0
0 0 0
1 1 1
Command Codes
W X X
X X X 0 US1
usa
Execution
Head retracted to track 0
No Result
Phase
SENSE INTERRUPT STATUS
Command
W 0 0
0 0
1
0
0
0
Command Codes
Result R ST 0 Status information at
R
PCN the end of seek opera-
ti on about the F 0 C
SPECIFY
Command
W
0 0 0 0 0 0 1 1 Command Codes
W -SRT HUT­
W
--HLT
NO
No Result
Phase
SENSE DRIVE STATUS
Command W
0
0
0 0
0
1 0 0 Command Codes
W X X
X X X HD US1
usa
Result R
ST 3 Status information
about FDD
SEEK
Command W
0 0 0 0 1 1 1 1 Command Codes
W
X X X X X
HD US1
usa
w
NCN
Execution
Head is positioned
over proper cylinder
on diskette
No Result
Phase
INVALID
Command W
Invalid Codes
Invalid command codes
(NoDp - FDC goes into
standby state)
Result R
ST 0
STO=80
2-99