Hi folks

My name is Rainer an I am a fan of old computers for over 20 years.
My primary interest now is in German computers or computers of German manufacturers but also computer history and historic computers in general.
(see also a part of my collection on my website http://horniger.de/computer/index.html )

My first touch with computers was the HP 97 of my father, when I was a teen. He used it to make simple calculations or just didn't wanted to do all the effort using the UNIVAC of the university for a calculation.
I was and still am fascinated by the red LED display, the sound of the printer and the stack base input (Reverse Polish notation).
Although HP computers were always interesting for me, I never put my focus on them - maybe cause they weren't easy to get.
I now have some in my collection, which found the way to me themselves:
the nice 486er EISA NetServer 4d/66 LM, which I got from a friend and the HP 9000 D Class server, which I got from the company, I worked for.

Then some years ago I was in the company, my girlfriend works for, to have a look at an interesting laboratory database system.
It was running on a HP 1000 A900 machine. A former colleague of my girlfriend was developer of this database system. He knows everything about using and programming the HP 1000 computers (RTE, assembler, fortran,...).
The company (frey) also developed a serial multiplexer for the HP 1000 to connect multiple serial terminals (or laboratory analyzers) to the parallel interface.

A bit of research and I was fascinated in the PDP-11 killer series of HP, which I didn't knew before.
I looked everything the HP 2000 and HP 2100 blinkenlight models from the beginning up to the A990.
A year later, the company wanted to get rid of all the remaining HP 1000 stuff, because the interest in their own history disappeared. This former colleague and now friend asked me and of course I took the rest, which was the A900, an A400, an HO2392A terminal, some external hard disks and two of these multiplexers.

Back then, the A900 had a problem while accessing the SCSI hard disk.
The A400 was setup to show the history of the companies' database system.

Last year, I persuaded this friend, to show the HP 1000 on the VCFB fair (Vintage Computing Festival Berlin), which he did:



I had my own exhibition on this fair, so he had to do all the preparation for the HP 1000 exhibition.

Because I still have little idea of RTE and the HP1000, my friend started to write down a great documentation, starting with the A400 system.
But the suddenly... the A400 CPU stopped working while doing a copy process on the hard disk.
On the next reboot the self-test stopped with all LEDs on, which means "Microcode test Failure" according to the manual.

Although I also want to reactivate the A900 (the complete laboratory database system needs the bigger CPU to have all features running), I now want to get the A400 back to life.

I have an idea of how a computers works and also some experience in repairing computers (soldering... up to logic analyzer - and yes here's another piece of HP equipment: HP 1650B), but no idea of the HP 1000 series in deep.

So here are my questions:
The manual says on teh "Microcode test Failure" error: CPU or powr suppy.
Do you have any tipps how to narrow down the problem?
What tests can I do for thsi?
What can I do for measurements?
How would you start to find the defect(s)?

thank you

Rainer

Thanks again for the tip with the PROMs. This could be a good start...

Are these PROM HP manufactured?
Or do you know which manufacturer and type/ model these PROMs are?

PROMMER/ READER I own are:
- DataIO System19
- Kontron EPP-80
- SUNSHINE EW-70x
- HI-LO systems ALL-11C

thanks

Rainer

Thanks for your help and the link. I already know the documents onbitsavers.

Unfortunately there's only a short description of this error, but not how to try to fix.
We checked the voltages, so it seems, that power supply is OK. (We haven't tried to check, if it's stable enogh --> old capacities...)
But how can we find a problem on the CPU board?
Or is it uncommon or not possibile to repair a CPU board instead of replacing?

thanks

Rainer