This is a long shot...
I'm looking for the General Logic Unit (GLU) chip for the Apple IIc Plus.
It is labelled as part number 342-0243-A and is a PAL20X4 gate array chip, and is indicated on the IIc+ motherboard as UE9.
As shown here: http://www.applelogic.org/files/3420243A.png
If anyone can help either supplying a replacement or has the code to program the PAL20X4 with a programmer (assuming you can still get one of those blanks) I'd certainly be grateful.
The jdec file can be found here:
https://downloads.reactivemicro.com/Apple%20II%20Items/ROM_and_JEDEC/IIc+/GLU_Unit/
Unfortunately i do not know a modern replacement for the PAL20x4 ...?
Maybe RM can also supply you with a programmed replacement.
Good luck
I've seen PAL20x4 listed on eBay, but they aren't common. Modern GALs which are more readily available are mostly the GAL16V8 or GAL20V10 or similar like the Atmel ATF20V10. I'm not sure either of those could be used to replace a 20X4.
RM does not list the //c GLU on their store. They have the GAL for the //e listed so I am assuming if they had the //c GLU it would be for sale.
it seems they do ...
https://www.reactivemicro.com/product/upgrade-gal/
Thanks! That's a help and I'm embarassed I didn't dig any deeper.
My google-fu is slipping...
It is definitely not obvious, if you look under the //c category on their site it isn't listed. You kind of have to know exactly where to look. So definitely good it is posted here now. I find a lot of questions related to Apple II that I have get answered by google matches from this site. Over the years it has become kind of a treasure trove of info including a lot of pointers to things elsewhere.
The PAL20XRP4 was available from more sources, and it includes the 20X4 functionality.
The XOR array is not strictly required; it just reduces the number of product terms needed for each registered output. A PLD with enough product terms can replicate the same logic.
In any case, you would need the source equations in CUPL, etc., to compile for a different PLD. A .JED file can't be ported to a different PLD.