The Sinclair QL Forum

Derek_Stewart wrote: Fri Feb 21, 2025 8:59 am

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.

I have a set of the old DOS programs - OPAL Junior - which handles PAL's and GALS - the logic programming is very similar - the hard part is remembering that PAL's are much more restrictive - in that they don't support too many clever things like a mix of registered and cominatorial on the same chip - at least that's been my experience - GALS can do pretty much anything a PAL can - as they were designed to replace them