ZiLOG System 8000 Hardware Reference Manual

HRM Zilog
Table 4-16 Disk Controller Jumper Settings for Memory
HRM
JUMPER
GROUP (E)
E1,E2,E3
E41,E42,E43
E4,E5,E6
E7,E8,E9
PURPOSE
Permit inserting
one watt state
whenever any
on-board memory is
accessed or whenever
only on-board EPROMs
are accessed.
Permit selecting
either 2716 or
2732 EPROMs.
CONNECTION AND RESULT
E2 to E3 and E42 to E43:
Inserts one wait state
during access of any
on-board memory.
E1 and E3 and E42 to E43:
Inserts one wait state
during access of EPROM
only.
E41 to E43:
No wait states for control-
ler on-board RAM or EPROM.
E4 to E6 and E7 to E9:
Use
2716 EPROMs.
E5 to E6 and E8 to E9:
Use 2732 EPROMs.
4.'5.2.3 Command and status Words: The disk drive control
bus contains a command word when the direction line is
activated, otherwise it contains a status word. The number
of the command or status words is determined by the coding
of CWDO and CWD1.
Command Word O--Command Word 0 is used to select one of fif-
teen.drives by a four bit unit address (uA).
Command Word 1--Command Word 1 is used,
two low-order bits of Command Word
binary address of the desired cylinder
Cylinder Address Register (CAR).
together with the
0, to establish the
specified by the
Command Word 2--Command Word 2 has three basic purposes:
(1) select forward or reverse offset, (2) select early or
late data strobe, and (3) select one of three possible head
positions by the HARD and HAR1 bit positions.
Command Word 3--Command Word 3 enters a Diagnostic mode,
Customer Engineering (CE) mode, Rezero (Return the heads to
cylinder zero), clears a fault, or establishes which heads
are to be write protected.
4-25
Zilog
4-25

ZiLOG System 8000 Specifications

General

Brand	ZiLOG
Model	System 8000
Category	Desktop
Language	English