Paul Robson sent me the Battle Star Galactica Space Alert game- it has a Rockwell B6001, which is a modified calculator chip. I made a pretty nice die shot from it, but we could never find any documentation on the processor, so we didn't know where to start on the ROM dump or how to interpret it if we did. He even contacted the original programmer, but didn't get much info. There is a Rockwell patent (US4339134) with code for a calculator/blackjack game that probably uses a similar processor.
BSG:SA also only has a 512-byte ROM. My understanding of the 511-byte size is that the processor uses an LFSR like the TMS-1x00 chips, but doesn't have the extra circuitry to handle the all 1's state, so one byte can't be accessed. The Sharp SM51x processors are similar. TI must have had a patent on accessing the extra byte.