I wrote free play/high score saves for all the Sega vector games, saving the data to the C000-CFFF memory location that is supported by VectorLabs multigame. Works in MAME but I never had the multigame kit to test it. I tried making standalone hardware to test on one of my games but haven't been able to work on it.
I know
@philmurr created a kit for Astro Blaster which uses the same hardware. Maybe we could collaborate to get this done finally.