The Sinclair QL Forum

Hi,

I can not find anything with regards to the PCML PAL code.

I have an old DOS based HiLo Systems ALL03A eprom programmer that will read and write to the PAL chip installed in the PCML board.

I have some newer USB eprom programmers, like: MINIPRO TL866CS, does not suopport the PAL chip.

If you want send me the PCML board with the working PAL chip, I will see if I can read the PAL code.

Derek_Stewart wrote: Thu Feb 20, 2025 7:12 pm Hi,

I can not find anything with regards to the PCML PAL code.

I have an old DOS based HiLo Systems ALL03A eprom programmer that will read and write to the PAL chip installed in the PCML board.

I have some newer USB eprom programmers, like: MINIPRO TL866CS, does not suopport the PAL chip.

If you want send me the PCML board with the working PAL chip, I will see if I can read the PAL code.

Thanks for the offer Derek, but I don’t want to risk loss/damage in the post. It would have been nice to read the PAL but it’s not essential. Will try re-instating the legs on the 0k and see what happens

Just noticed there’s an image of what seems to be a 0k disk only version (based on the ROM label) in this thread:

viewtopic.php?p=48471&hilit=Pcml#p48471

But it doesn’t look like any PAL pins are missing

I tried the PAL from a PCML RAM board just in case it was the same one, but it wasn’t of course

It may be posssible to reverse engineer the PAL by simply working out which pins are connected to where. This task is made slightly easier in the sense that some pins on the PAL can only be inputs - others can be both - but as an example if a pin is tied to a CS pin on the FDC chip - then that pin is an output for sure.

Totally off topic but I can’t find any pictures of the PCML RAM card online, is it rare?

t0nyt wrote: Thu Feb 20, 2025 8:35 pm Totally off topic but I can’t find any pictures of the PCML RAM card online, is it rare?

Wouldn't necessarily say it was rare. But relatively unpopular. It was one of the RAM expansion boards that didn't have a through-connector. So, if you wanted RAM and (the RAM needs to go in first because of the floppy connectors) keep the option open for floppy drives, you were at a dead end.

tofro wrote: Thu Feb 20, 2025 9:58 pm

t0nyt wrote: Thu Feb 20, 2025 8:35 pm Totally off topic but I can’t find any pictures of the PCML RAM card online, is it rare?

Wouldn't necessarily say it was rare. But relatively unpopular. It was one of the RAM expansion boards that didn't have a through-connector. So, if you wanted RAM and (the RAM needs to go in first because of the floppy connectors) keep the option open for floppy drives, you were at a dead end.

Ironically it’s probably of more use today, than it was then, with storage devices like Qimsi for the ROM port

Pr0f wrote: Thu Feb 20, 2025 8:35 pm It may be posssible to reverse engineer the PAL by simply working out which pins are connected to where. This task is made slightly easier in the sense that some pins on the PAL can only be inputs - others can be both - but as an example if a pin is tied to a CS pin on the FDC chip - then that pin is an output for sure.

Hi Prof,

I was just thinking the same idea, maybe work out the PAL equations to map the PCML 256K ram to the QL memory.

I have not much experience of writing PAL code, but I will see if there is any books or tutorials available.

From what I’ve read the R devices hold 4 internal states (can’t remember the technical term) so even if you read every state it can change

From the point of view of me getting my 0k board working I’ve come to the end of the journey for the time being as I’ve realised that after trying the PAL from the memory board the 0k isn’t even recognised as a floppy drive any more

It’s been consigned to the spare parts bin

Many thanks for all the suggestions/help everyone