The pinouts of an FPGA are even *more* different. And programmable logic devices aren't really particularly good at replacing ROMs. The smaller ones don't have enough memory (or logic) to do it, and the larger ones are expensive and only are packaged in high-pin-count surface mount packages. If you get an EPROM or Flash memory chip in a PLCC or other small surface mount package, you should be able to make a small adapter board that plugs into the 2513 socket. Gateway Electronics closed their Denver store on December 31. Some of the other 6502 Group members and I organized a wake. We ordered a bunch of pizzas, and a good time was had by all, though we were certainly sorry to see them close. Apparently one of the founders died not too long ago, and his widow wanted to cash in her share of the business. Their main assets were the real estate, so they're selling that off. Apparently they're going to keep the Saint Louis store open, but in a new location. Anyhow, the reason I bring that up is that the last purchase I made there included their little plastic bin of 2513s, but judging by the markings they are all the common upper-case variant. I also bought some INS8073 and INS8070 parts, which are National Semiconductor microprocessors with and without a very tiny BASIC in ROM. The architecture is similar to the SC/MP, but not binary compatible. Now I need to find the data sheets and manual... I tried to buy their assembled demo unit of the "Animal Sounds Piano" kit, to give to my niece as a birthday gift and drive my sister insane. But they wouldn't sell it to me. They claimed it was going to be shipped back to headquarters in Saint Louis, but I think they really plan to smash it with a sledgehammer or take it to a shooting range. For any other sadists out there that want to drive family or (soon-to-be-former) friends crazy, you can buy the kit from Alltronics. or LNS Technologies.