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Model 64100A - Service
8-6.
INPUT/OUTPUT
(I/O).
The I/O PC board
contains the necessary circuits
for:
(1)
processing the various interrupt requests and informing the CPU that
an
interrupt
condition
exists,
(2)
providing
the· necessary
"hand-shake"
operations with RS-232C and HP-IB peripheral devices
(e.g.,
the mass storeage
disc,
line printer or teletype),
(3)
decoding instructions
from the CPU and
thereby
providing a means
by which
the CPU
can select specific
circuits or
peripheral devices to communicate with, and
(4)
providing an audible alarm to
indicate when certain events have occurred.
8-7.
DISPLAY CONTROLLER,
DRIVER
AND
CRT.
The display section of
the 64100A
system consists
of the Display Controller and Display Driver PC boards and the
CRT.
The Display
Controller provides
the
CPU with
"scratch-pad"
memory
capability via
an array of random-access
(RAM)
read/write memory chips.
In
addition,
it generates the various video control signals for displaying system
operation
on the
CRT display.
The
Display
Driver
PC board
develops
the
necessary sync, drive and high voltage signals for creating the CRT display.
8-8.
REAR PANEL.
The Rear Panel PC board contains:
(1)
operator-controlled
switches for controlling the mode of operation of the 64100A Mainframe, (2) two
RS-232 interface connectors; one for when the Mainframe is serving as a "modem"
and one for when it is serving as a "terminal",
(3)
two sets of RS-232 current
loop (i.e., teletype) input/output terminals, (4)
a HP-IB interface connector,
and (5) a "loop-back" circuit for testing the RS-232 circuits.
8-9.
KEYBOARD.
The
64100A Mainframe
uses
a
keyboard
that provides
the
operator with three basic means of communicating with the 64000 system:
(1)
a
77-character ASCI-II typewriter format basic keyboard,
(2) a set of edit keys.
and (3) a set of "softkeys"
for increasing
the versitility and "friendliness"
of the system during system development operations and Mainframe self-testing.
8-10. MAINFRAME SIGNAL DISTRIBUTION.
Two methods
are
used to distribute and
route
the
various power,
control
and data
signals
throughout
the
64100A
Mainframe:
(1)
a
printed circuit Motherboard and
(2)
a system
of
ribbon
cables.
The
Motherboard,
however,
is
the primary vehicle for distributing
power
and most of the
data
and control
signals to and
from the various
PC
boards in the Mainframe cardcage.
8-11. The
Mainframe Power
Supply is
mounted directly
to the Motherboard
by
means of 12 screws that also serve
as electrical connections between the power
supply and
the
Motherboard.
The screw pattern and the associated electrical
signals are shown below:
MF
8-2
-12 Vdc
0
+17 Vdc
0
GSEN
0
+40 Vdc
0
LINE SYNC
0
LPOP
0
LIR15
0
o
-3
Vdc
o
-5.2 Vdc
o +12 Vdc
o GND
o
+5 Vdc
Power Supply Connections (Bottom View)
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Troubleshooting
