The website 64HDD has plenty of information about mods and upgrades for Commodore C64 enthusiasts. They have an article explaining their exploration of using CPLDs in C64 hardware mods. Their first CPLD project, explained in the article, explores the build of a 256kB memory expansion board originally designed using TTL chips. The project uses the since discontinued 64-macrocell XCR3064 CPLD by Xilinx, largely because at the time he wrote the article the PLCC package was the easiest to work with. (Of course, you could use our CPLD Development Board for a project such as this!)
Whether you’re a C64 hobbyist or a cutting edge developer, you can get your own CPLD development board for $15 including worldwide shipping from Seeedstudio.