Electronics > FPGA

Help with converting old PALs to GAL

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Emulator III:
Hi there,

I am trying to restore an old piece of audio hardware, which incidentally is the same model as my user name. It is a digital sampling keyboard which was made in the late 1980's

The trouble which I (and others) are having is that the unit is full of old custom PALs right through the logic and computer circuits. Some of these are failing.

I have been working with another user trying to read and write some of the PALs. We think we've been successful in reading some so far and have some JED files generated from them.

However I've been struggling with the next step, which is trying to write them back into newer GAL chips. I have the trusty TL866 II programmer which does seem to write the chips OK. I can read back the data and verify after writing. But I still can't get them to actually function in the host machine.

I was wondering if anyone could assist who has had some experience dealing with this sort of problem? Anyone here successfully ported old PAL22V10 over to GAL22V10? I can provide the JED files we have so far if anyone would be so kind to take a look at them?

Thanks for your time
Luke (EIII)

PAL22V10 and GAL22V10 should have the same Fuse Map, so the JED file matches both types.
However, first check that the chips are not read-protected. Then you will read JED but there will be no data in it.

Emulator III:
Hi up8051,

Great name by the way! Have had many years repairing circuits with the 8051 at the core!

Interesting as I thought there would have to be some process to port the JED over, such as the PALtoGAL.

Anyway it's looking like the JED files are no good, or the chips are protected. It's not reading only 1's but it looks pretty rubbish.

Can anyone advise on any other current methods to to read a PAL22V10?

Thank you for your input

Show the readout JED file.

Converting from PAL (for example PAL16L8  to GAL16V8)  do GAL path is:

1 Read JED file
2 Convert JED to equations (JED2EQN tools)
3. Recompile to GAL target

If PAL is protected that only path is reverse engineering.
Service manual for Emulator III is available so there may be a lot of useful information.

Emulator III:
Hi up8051,

Thanks for the prompt reply.

I see, so you do have to reverse to equation and then re-compile? I was trying to use PAL to GAL but no idea if I was using it correctly... I am completely new to this world but trying to learn to save our EMU's!

Please see the JED attached. Let me know if you need anything further.



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