ZiLOG System 8000 Hardware Reference Manual page 126

HRM 2ilog HRM
CM defines the current operation by the CMD code and several
command modifier flags.
CM:NR: no retries; use OF
CM:NE:
no error correction
CM:NO: no offsets during retries
CM:CMD:
0:
nop
1 :
write RAM
2 :
read RAM
3 :
select drive
4 : priority select
5 : release
6 : reset fault
7 :
position ( seek/rezero)
8: write format
9 :
write long
A: write
B: reserved
C: read format
D: read long
E: read
F: size disk
COMMANDS
NOP is provided for diagnostic purposes; IP is posted
immediately. The microcode revision is returned in CT.
WRITE RAM copies data from the specified host memory address
to the data buffer space of the controller from location 0
up to local variable and packet storage. Provided for diag-
nostic purposes.
READ RAM copies data from controller memory, starting at
location 0, to host memory. Provided for diagnostic pur-
poses.
SELECT causes the specified drive to be selected and its
status returned in DS.
PRIORITY SELECT is provided for dual access support.
RELEASE is provided for dual-access support.
RESET FAULT is provided for diagnostic and error recovery.
A RESET FAULT command is issued to the specified drive.
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Zilog
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