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So my beloved PET has started to act strange... which is rather annoying as I'm trying to test some bits and pieces before sending them out to people... It won't reliably start unless I put my finger on pin 27 of the CPU... If I leave my finger there it performs perfectly. Could this be a...

I recently discovered the joy of HP Digital Signatures, i.e. to monitor a digital signal during a period of time and to generate a 'checksum' of the data in between as a way of characterising the signal you just observed. For microcomputer systems a good test set-up is to install a NOP adapter...

I would quite like to bodge PETTESTE2KV04 to work in the H7 slot of a 2001-8 with 6540 ROMs so the machine would only need a single ROM to start Has this been done before? I don't want to re-invent the wheel if it has... I was considering putting the following snippet at the top of the...

I have never used IEEE488 on my PET but am warming up to it... I thought I would like to test the functionality first at the PET end. Specifically I would like to test the PIA#2, the VIA and the MC3446 devices. Starting with data it seems the PIA#2 drives a pair of transceivers... is it...

Does anyone know which fonts were used for the disk drive labels? Are there reproductions available? The label on my drive is covered in drizzle from a poor paint spray job by a previous owner.

I'm sharing the gadget I built to get my PETunia working... Has 16 sets of ROMS (see PDF on github, link below, for contents), 32MB of RAM, Reset and EAzy NOP Generator. :cool: It's nothing mind blowing but I do have a few spare PCBs which can be hand assembled if people are interested. I...

Given the success over the summer with Petunia (my 2001 PET) I couldn't resist buying a very crusty not working 8050 dual floppy drive... this looks Very Challenging! I am wondering what the first step should be... Power supply? Should I replace the 0.1uF+2x2500pF Suppression Filter thing...

I have recently bought a Commodore PET 2001-8 in non-working state and am here to get some help on fixing it. My original experience with computing was a HP65 calculator, Cosmac ELF 1802, PET and the like and ICL1902 and PDP11 mainframes... that was a long time ago but I seem to have made a...

Hi, I'm new to this forum (although not new to computers ;) ) and have recently purchased a not working Commodore PET 2001 which I hope to repair... I have video which is good and characters are nicely formed so that is good I am working through the ROMs (these are 6540s)