Introduction; Quick Checks - HP 9845B/C CE Handbook

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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.
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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.
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