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Good detective work. Let's hope that is the problem. If not, it could be something around the IC like a bad solder joint, faulty PCB via etc. Dave

The OP gave up I think... Dave

It looks like the on-board IC drives the connectors that are marked as /WRITE ENABLE on the rear of the little PCB. Assuming nothing is plugged into these 2*3 connectors, then it looks like the IC does nothing... If the PAICS toolkit is plugged into ROM socket UD11 (starting address $A000)...

I am a machine code programmer - so 20 hex passes! That is TIM - the machine code monitor (as I thought - see post #42). Go and hunt down the Commodore manual for TIM. As you have spotted - there are no buttons on a standard PET to reset it or to enter this useful machine code debug monitor...

The VIDEO signal looks healthy. The SYNC signal not. These "Pre Rnn" signals should be logic levels. The VIDEO signal is, but the SYNC signal is not. If I understand your oscilloscope display correctly, the settings are Y = 200 mV/div and X = 20 ns/div. This signal is way too low (in terms of...

A bit of an 'outfield' thought... There were digital cassette units around a long while ago. Fairly recently I found one and someone bought it and found it worked fine... The unit is a solid state (USB-type drive I think) that looks like a cassette. You load it digitally from a PC and it just...

As this is your first post, welcome to VCFED. How did you check that the 'old' disks were clean? Did you just 'peek' through the window of the disk, or rotate it with your fingers whilst looking at the surface for a full rotation? What does the 'old' disk look like now it has been in the...

Most of what I was reading made no sense at all (to be honest), so I am just as surprised as you now you have some sense out of it. All I can think of is that there is a bad connection, solder joint, or something else that was wrong (e.g. a reversible connector that was the wrong way round) -...

Is it possible you installed the cable connector at the PET end the wrong way round? The connector should have a plastic polarising key installed, but (9 times out of 10) this key is missing, giving you the 'opportunity' to install the connector the wrong way around. Dave

>>> How do you do a SCART lead on a BBC? I bought mine. It has a Beeb video DIN connector on one end and a SCART connector on the other. There are websites that detail the wiring if you want to purchase your own connectors and make up your own cable. EDIT: Check here...

That is an excellent idea! Dave

The IEEE 488 PET book agrees with the schematic. The test program for NRFD (Not Ready For Data) uses PEEK/POKE address 59456 (which is the VIA pins PB1 and PB6). There is something wrong somewhere. What is A9 pin 6 connected to then (the supposed NRFD MC3446 bus signal - mislabelled as NFRD)...

Happy birthday. Full marks to your wife :)! The semiconductor ICs must be BGAs. Dave

That 'feature' has been around for a while - until you are out of moderation. One more post and you should be as free as a bird! Dave

Welcome Matt. It is not that often the Daleks come out shooting new VCFED members down! Dave

That makes more sense... Have you tried pressing both buttons together then releasing the reset button first? There is a diagnostic signal that is read just after the machine is reset. This causes the ROM to drop into TIM (the machine code monitor). Dave

The ROM is the PAICS toolkit that adds additional commands to the PET's BASIC. See: https://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/other/toolkit-b000.txt However, either this ROM is in the wrong socket or it starts at a different address. The $B000 toolkit starts by entering...

Excellent! I would give it at least 20 passes for good measure. Did you check the ROM checksums from the previous PETTESTER screen for correctness? Oh well, it seems to run! Dave

Oh well, that answers my query then... Dave

>>> Hi Dave, thanks for the greeting ! No problem. I spent a little time (many years ago) in Portugal at Tapada do Outeiro power station in Medas, Porto. >>> I'm in Portugal. Is that solution still applicable ? I will send you a DM. Dave