I've only even seen this hardware twice. I doubt you'll find any docs or software for it online. Very little of Sega's arcade docs/hardware have been spotted in the public domain, probably because often titles were first party, or the gear needed to be returned to Sega afterwards. That said, I believe the STV Sophia is basically the same as a Saturn Sophia. It would make sense if the hardware was compatible with the same software. The programmable DRAM cartridge would have had software of course, but it'll be something simple that was written in an afternoon probably. Acclaim had a system that I saw surface, and Sega was doing pdf docs by that stage, so chances are what you're after is rotting away on those acclaim backup tapes in Kevin's garage....