Zenith Z-100 PC series Service Manual page 108

Chapter S
Troubleshooting
Three hardware/software diagnostic aids are available for trouble­
shooting the CPU/memory card. These are the disk-based diagnostics
(CB-S063-28), the ROM-based diagnostics, and the LEDs on the card and
on the backplane board.
The LEDs can be used to isolate failures of major portions of the
computer system. The ROM-based diagnostics include the power-up test
(performed automatically each time the computer is turned on), and
several other tests which can be selected from a menu. The use of these
tests is explained in the service guide for Z-lSO PC Series computers. The
disk-based diagnostics are shipped automatically to service centers and
kit customers, and are more thorough than the ROM-based diagnostics.
NOTE: Servicing the CPU/memory card with an oscilloscope is difficult.
In order to obtain reliable information, it is necessary to write machine
language programs that exercise the hardware so that predictable,
repeatable results are obtained in desired locations. No such programs
are provided in this manual.