I inherited this 6800 Single Board Computer from my friend in the Cape Computer Club, Barney. I also got this SWTPC chassis with an MP-B SS-50 motherboard which he'd modified by adding an M68BSC-1 (Bus System Card) two-slot motherboard.

The SS-50 bus supplies 8V to all the slots, and the boards have 5V regulators on them (same as S-100). Barney added a transformer for +12V and -12V as well as regulators since the EXORciser-bus supplies regulated voltage to all the cards.

M68SAC1 datasheet from the 1979 microcomputer development systems and subsystems, from which you will also learn that the M68MEB1 is an M68SAC1 with MEC68MIN2 Minibug II fitted, and when also fitted with M68IOS1 firmware it is used in the M68ADS Autonomous Development System.

MEC68MIN2 is a 6830 Mask ROM with Minibug II -- here's the datasheet from the Motorola 1981/82 Memory Data Manual.

M68IOS1 is a complete kludge. It interfaces to a keyboard and display, and send / receives the characters via the one ACIA to the other ACIA where Minibug handles it. Keyboard -> IOS -> ACIA -> serial -> ACIA -> Minibug, Minibug -> ACIA -> serial -> ACIA -> IOS -> display.

Mask ROM part numbers

• SCM44506 is Minibug 2 at E000 for M68SAC1 (MEC68MIN2 / MCM6830)
• SCM44516 is IOS at DC00 for M68SAC1