Zenith Z-100 PC series Service Manual page 111

Page
5-4
Troubleshooting
")
Table 5-1: Error Messages
+++ ERROR: CPU failure! +++
+++ ERROR: ROM checksum failure! +++
When either of these messages occur, the CPU circuitry has a fault.
Replace the CPU/memory card.
+++ ERROR: RAM failure! Address:XXXX:YYYY, Bit: n, Chip UXXX +++
+++ ERROR: Parity hardware failure! Address:XXXX:YYYY, Chip UXXX +++
+++ ERROR: Parity failure! Address: XXXX:YYYY, Chip: UXXX +++
These messages indicate that the CPU is unable to read from or write to
RAM or video memory. This may be caused by improper configuration
of the DIP switches or jumpers. Refer to Chapter 2 and make sure that
the appropriate DIP switches and jumpers are correctly set for the
amount of memory installed in the computer.
If the chip number displayed is a 200 number, such as U22?, the failure is
on the CPU/memory card. If the chip number is a 300 number, the
failure is on the video/floppy card. Replace the IC indicated in the
message.
+++ ERROR: Timer Interrupt failure! +++
This error message indicates the possible failure of the interrupt control
and/or timer logic in the CPU circuitry. Refer to Chapter 2 and make
sure all DIP switches and jumpers are correctly set for the options that
are connected to the computer. Also make sure all optional boards are set
up properly. If that does not correct the problem, replace the
CPU/memory card.
+++ ERROR: Invalid/No keyboard code received! +++
Normally this message is caused by the keyboard being unplugged. If the
keyboard is plugged in, the problem may be in the keyboard or keyboard
cable. Replace the keyboard and/or keyboard cable.
+++DISK ERROR: Drive not ready! +++
These error messages are usually caused when the system attempts to
boot the operating system from the disk and no disk is in the disk drive.
This may also be caused by a faulty disk or faulty disk controller
circuitry. Make sure there is a disk in the drive, that it is inserted
correctly, and that the drive latch is closed. If a disk is properly inserted
in the drive, try another disk or try booting from the other disk drive.
No system
This message occurs when a disk does not contain an operating system.
Make sure the disk is inserted properly and that it contains a valid
operating system.