Quote:
Originally Posted by Slothie
The original "Basic 1" commodore PET (With the "*** Commodore Basic ***" banner rather than the "### Commodore Basic ###") had built in diagnostics that would activate by holding down a pin on the user port. Later versions apparently removed this feature rendering the LED on the main board redundant (possibly not fitted?). Commodore also made a cable loom that connected to the keyboard, cassette ports, user port & IEEE port and tested the ports - I believe the software came on cassette. I looked for a link to information on this, but ten or so minutes of searching yielded nothing but I did find the attached manual which might be interesting or give some clues/useful info. Looking through the archive sites on zimmer.net or 6502.org might prove fruitful.
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I hadn't seen before that Commodore had removed the Diagnostics (Only on PET 2001?, but it seems the 30xx replaced that) after BASIC-1 - Maybe they were short of space across the ROM's.
But I have now discovered in this book that I recently-found (which also covers 6502 assembly-language instructions & programming on the PET), it says that on the later firmware, pulling Diagnostic_Sense low firmware goes into a Monitor program instead - Where most of the diagnostics are still there? (See page 262 etc):
http://www.primrosebank.net/computer...Raeto_text.pdf
The loopback connections were listed in this text file:
http://www.zimmers.net/anonftp/pub/c...iagnostics.txt which was from the index of PET info, here:
http://www.zimmers.net/anonftp/pub/c...pet/index.html
There's also lots of various test utilities etc, here:
http://www.zimmers.net/anonftp/pub/cbm/pet/utilities/
I also discovered these seemed to have been used with a much more advanced original Commodore 6502-replacement Diagnostic-tester - which could have been rather useful to have - with details inc. reverse-engineering of it here:
http://www.6502.org/users/andre/peti...iag/index.html
Which I found from Commodore PET repair info page (which also has links to keyboard repair info):
http://www.6502.org/users/andre/petindex/repairs.html
There's some useful summaries of diagnostics in this:
https://www.classic-computing.org/wp...Bit_Repair.pdf
- Although website seems to be down, but can view a cache of it:
https://webcache.googleusercontent.c...&ct=clnk&gl=uk