Love the Super System research, will be following that very closely. So awesome to emulate things for the very first time.
Current emulation is blocked by a missing dump of the M50458 char ROM, I bet that it won't be dumpable hence we need to write a trojan on a real board. I also don't think that is currently putting any reasonable vram data yet, but we'll see once that we find a board ...
Current MAME driver is here, with my current discoveries:
http://mamedev.org/source/src/mame/drivers/nss.c.html