One of the reasons there area couple of FPGAs in there is that some of the ICs that they really wanted to use aren't produced anymore. One of them is the FM syn

One of the reasons there area couple of FPGAs in there is that some of the ICs that they really wanted to use aren't produced anymore. One of them is the FM synthesis IC that he talked about in this video. Quickly looking at Mouser and Digi-Key suggests that nobody manufactures FM synth ICs any more. Same with video display ICs. FPGAs are used to emulate these 1980s-era ICs, which seems reasonable since there's no reliable source for the Real Thing.