ZiLOG System 8000 - 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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