C64’s Programmable Logic Array [PLA chip] and how to make a replacement

I’m a geek, you’re a geek, we’re all geeks.

And geeks don’t always use stock parts when making their projects, even if said project is to build a commodore 64 from scratch.

One of the custom chips found on the C64 motherboard is a Programmable Logic Array (dubbed PLA) which contains combinatorial logic and is responsible for dictating the memorial map of the computer, enabling bank switching. The PLA is the glue logic that holds the Commodore 64 computer.

But the chip is no longer manufactured, so fixing up a broken C64 or building a brand new one require either to source a vintage (used) part, or to come up with a replacement.

Today’s article will explore such a replacement.

2023/05/222023/07/11 by wereallgeeks Categories: 100% Geek, C64PLA, Commodore 64, Computers and technology, Geekyness, Projects, RetrocomputingTags: C64, C64C, commodore, Commodore 64, Daniël Mantionne, Daniel Mantionne, DIY, drop-in replacement, electronics, gal20v8, GALPLA, modern equivalent, pcb, PCBway, PLA, PLA20V8, Programmable Logic Array, replacement, shared project, Simple Programmable Logic Device, soldering, SPLD 1 Comment

brand new Commodore 64 Complex Interface Adapter chip replacements (finally)

I’m a geek, you’re a geek, we’re all geeks.

And geeks fix up old computers. Or build them.

However, chips from the 80s are no longer in production. Sometimes there are modern replacement, such as EPROMs to replace ROM chips or FPGAs to replace old ICs. But sometimes such replacement doesn’t exit.

This was the case with the Commodore 64 (and Amiga) Complex Interface Adapter (CIA) chip. until now.

2023/04/192023/07/11 by wereallgeeks Categories: 100% Geek, C64CIA, Commodore 64, Computers and technology, Geekyness, Projects, RetrocomputingTags: 100% Geek, 1nt3r.net, Amiga, C128, C64, C64C, CIA chip, commodore, Commodore 128, Commodore 64, computer, drop-in, drop-in replacement, electronics, FPGA, Geek, Geekyness, j-cia, Jani Laatikainen, microchip, MOS-6526, Perifractic, replacement, retro recipe, Retrocomputing 1 Comment