ZiLOG System 8000 Hardware Reference Manual

HRM 21
Zilog
HRM 21
/ WORD COUNT / The number of words to be written to the disk
is sent to the controller through the word count control
register pair, CP8 and cpg. A word count greater than a
single sector length is interpreted as a request for a mul-
tiple sector write.
/ ADDRESS / The 24-bit address of the host data buffer is
sent to the controller through a register triplet; CP10,
CP11, and CP12.
B.5. Read Detailed status / UNIT / ADDRESS /
The Read Detailed Status command transfers three words of
the detailed disk status for unit number UNIT to the host
system memory beginning at location ADDRESS. The act of
reading detailed status clears the operation error status
byte unless the read status command itself times out. In
this case the time-out error will be set. See Table 11 for
the error status byte definition.
/ UNIT / Unit is written to the controller through CP1. Any
value between a and 3 is valid.
/ ADDRESS / The 24-bit addre~s of the host data buffer is
sent to the controller through a register triplet; CP10,
CP11,
and CP12.
B.6. Restore / UNIT /
The Restore command recalibrates the drive seek circuitry by .
positioning the heads at track zero, and clears the fault
status bit in the drive. The restore operation executes at
a slower rate than a seek to track zero. Recalibrate should
only be used in response to a drive fault. The controller
automatically provides a restore and command retry when a
drive fault occurs unless that option has been reselected.
/ UNIT / Unit is written to the controller through CP1. Any
value between zero and three is valid.
B·.7., Null
The null command presents an operation ending status code
"operation completE~" and performs no disk or controller
operation.
B-3
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B-3

ZiLOG System 8000 Specifications

General

Brand	ZiLOG
Model	System 8000
Category	Desktop
Language	English