Hello all, I have an old Zenith ďlaptopĒ that runs on an 80c88 processor, and apparently was manufactured around 1985. Itís quite a beast of a laptop - size and weight, rather than computing power!.

Unfortunately it fails at power-on with a Timer Interrupt Error.

Zenith laptop.jpg

Iíve started digging for any info that will help with a fix, with not much to find on the error or generally on the computer itself. The manuals have some basic hardware descriptions, but Iíve not found any schematics or technical fault finding manuals.
If anyone has any hints or tips, your advice would be much appreciated. Also, if there are any other online forums that are better for this kind of question, appreciate the info.

Iíve already posted on a retro computer forum on Facebook, with some good advice for fault finding, however the fix remains elusive, so looking to the experts on this forum for any further advice.

https://www.facebook.com/groups/retr...8720313491155/

see also:

https://retrocomputingforum.com/t/ze...irca-1985/1454

I've managed to abort the initial self tests by pressing the multi-key combination after power up, which then goes to the onboard Monitor, however that's where it ends. Any keypresses once in the monitor result in an error beep, and nothing else happening. Dead end.

any suggestions, or anyone with similar experience?

all the best,
Rob