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_ 9845B/C Mainframe Diagnostics .
9845B/C
Mainframe Diagnostics
Introduction
This chapter
will
help you diagnose the 9845B/C Mainframe. The method used relies
on
the
9845B/C Test
ROM
and Binary Test Cartridge to isolate a faulty computer section. Both
ROM
and cartridge must be of the same revision letter. I
This chapter
is
divided into the major mainframe sections. Each section consists of the descrip-
tion of the tests for that section. Use Table to find the tests and sections
in
this chapter.
9845B/C Mainframe Diagnostics are:
• Processor/Memory Addressing
• Memory
(ROM
and
ReadlWrite)
• Keyboard
• Cartridge Drive
• Printer
Before you get to the various sections, use the trouble isolation procedures described
in
the
qUick
check service procedure.
Quick Checks
From the keyboard you can perform three checks to determine the basic condition of the
computer.
Press the CONTROL
and
STOP keys, then run
one one
or
more of these three quick
checks.
Keyboard
Press random alpha keys on the keyboard (three or four X's should
do
it)
and
press
execute. This generates an
"improper expression"
or
an "improper character"
error
and
an audible beep. If a beep occurs, the processor and operating system
are probably working correctly. The CRT section may be defective.
Tape Here
is
a more demanding processor-memory test.
See
if
a program can be en-
tered into memory from tape. Install a tape
and
"GET" a data
file
from
it,
or
"LOAD" a program
file.
Printer If the printer
is
installed, execute the following lines:
PR
I
NTER
IS
0 press EXECUTE
PR
I
NT
"e
h a
rae
t e
rs"
press EXECUTE
If the characters are printed, the printer
is
baSically working
and
the processorl
memory addressing
is
baSically operating.
09845-90039, rev: 4184
Note
The keyboard bezel assembly may cause the computer to appear
inoperative. To eliminate this possibility exchange the complete
keyboard bezel assembly including tape logic, keyboard logic
and
keyswitch assembly.
I
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