ZiLOG System 8000 Hardware Reference Manual

HRM
Zilog
HRM
AH
and
AL
form
the
'DMA
starting address
for
operations
involving a
data
transfer.
If
AL
is
odd the
command is
rejected.
UN
is the
SMD
unit number
0-15
to
be used for
the operation.
CY
is the starting cylinder number
O-n.
HD
is the
starting head
number
O-n.
VS contains control information for multi-volume drives.
For SMD it is set for O. VS:HB is ORed into the head ID
field during a format write.
VS:FS
VS:NW
VS:HB
force seek for volume select (CMD)
no wait for on-cylinder (MMD fixed heads)
head bias (volume select for CMD)
SC is the starting sector number O-n.
OF specifies four bits of head offset and strobe timing data
to be used if CM:NR(no retry) is set.
OF:O+
OF:O-
OF:SE
OF:SL
servo offset plus
servo offset minus
data strobe early
data strobe late
4.5.3.2 SHD Interface: The SMDC interface signals to the
SMD drives consist of the address and control functions that
are transferred on the Bit 0 through Bit 9 signals on the
SMDC A. The information on these lines is indicated by the
the individual CYLTAG,SELTAG, HEADTAG, and CONTAG tag lines
when true. CYLTAG- When true low, the ten bus lines carry
the cylinder address to the SMD. Since it is a direct
addressing device, the SMDC need only place the new address
on the lines and strobe the lines with CYLTAG-. The SMD must
be On Cylinder before CYLTAG- is sent. The bus lines should
be stable throughout the tag time.
HEADTAG- When true low, this signal is the head address
selected by the bits on the bus line.
4-40
Zilog
4-40

ZiLOG System 8000 Specifications

General

Brand	ZiLOG
Model	System 8000
Category	Desktop
Language	English