Tandy 1400LT Service Manual page 297

Instruction
Set (3)
-
Instruction Code
Phase R/W D, D, D, D, D, D,
D, Do
Remarks
Scan High or Equal
Command W MT MF SK 1 1 1 0 1 Command codes
W X X X X X H D US, US,
w +
C Sector I D information prior to command execution.
W + H
w +
R
W + N
+
w .
EOT
+
W + GPL +
w +
STP
+
Execution
Result R + STO
-+
Status information after command execution
Data compared between the FDD and main system
R +
ST 1
R + - ST2 +
R + C
+
Sector ID information after command execution
N
Recalibrate
Command W 0 0 0 0 0 1 1 1 Command codes
w x x x
x x
0
us, us,
Execution Head retracted to track 0
Sense Interrupt Status
Command W 0 0 0 0 1 0 0 0 Command codes
Result R + - STO Status information about the FDC at the end of seek operation
R
--
PCN
-+
Specify
Command
W
0 0 0 0 0 0 1 1 Command codes
W
+ -
SRT
- + -
HUT
-
w .
HLT ND
Sense Drive Status
Command
W
0 0 0 0 0 1 0 0 Command codes
W X X X X X H D US, US,
Result R i ST3 Status informatin about FDD
Seek
Command W 0 0 0 0 1 1 1 1 Command codes
W
X X X X X H D US, US,
W + - NCN
+
Execution
Invalid
Head is positioned over proper cylinder on diskette
Command W
t - - - - - - -
Invalid Codes
-
Result R i STO
+
STO=80H
Set Standby
Invalid Command codes (No op
-
FDC goes into standby
state)
Command W 0 0 1 1 0 1 0 1 Command codes
Execution Enter standby mode
Reset Standby
Command W 0 0 1 1 0 1 0 0 Command codes
Execution Disable standby mode
Software Reset
Command W 0 0 1 1
0 1
1 0 Command codes
Execution Same as hardware reset
F-28