ZiLOG System 8000 Hardware Reference Manual page 113

HRM
Table 1t-13
SIGNAL NAME
Zilog
Disk Controller and Disk Drive, Interface
Signals, Connector P2/J23, Slot 3
FUNCTION
HRM
Control Bus
CB7 to CBO
DIRECTION\.
Control Words
o
and 1, CWDO
and CWD1
Attention : '
ATTN\
Cycle Acknowl-
edge CYAK\
Attention
Acknowledge
ATTACK
INDEX\
SECTOR\
SEEK END\
DRIVE FAULT\
These eight signal lines are bidirectional.
Control signals from the Controller to the
selected drive are transmitted on these lines.
The DIRECTION\ signal controls the direction
transfer.
This signal determines the direction of transfer
over the control bus (CB7 through CBO). When
DIRECTION\ is high, the controller reads st.atus
information from one of the four status registers.
When this line is low the controller is sending
commands to the selected drive.
These signals identify one of four bytes that
can be
0
nth e con t r
01
bus. Th e DI R
:E
CTI O.N \
signal identifies the current byte as a c6mmand
or :status byte.
The controller sends this signal to all drives
to initiate handshaking.
Each drive generates the CYAK\ signal in .
res)onse to the ATTACK signal.
The selected drive generates this active-high
signal in response to the ATTN\ signal from
the controller. ATTACK then causes the
selected drive to generate the CYACK signal.
The selected drive generates an index pulse
for each revolution of the disk. Each cylinder
produces a pulse which is 2.5 microseconds long
and which occurs every 16.67 milliseconds.
Sector 00 immediately follows the pulse.
The selected drive generates this 2.5 micro-
seconds signal.
The selected drive generates this signal at
the end of a seek operation.
The selected drive generates this signal to
indicate an error condition within the
drive itself.
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Zilog
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