SEGA PART #171-6885A

Demux Multi-megabit PCB - Date 1994

Originally, I thought this PCB must be for 24 Megabit 32X games, but the advertised size of Star Wars Arcade comes in at 20 Megabit.  It appears that whatever game needs the 2-4 line demultiplexer gets this particular PCB, no matter the size.  This solution may have been cheaper at the time than purchasing a single ROM with the size requirement they needed.  This PCB includes space for 2 ROMs & and a 2-to-4 line demultiplexer.  Each ROM is 42 PINs.  The PCB serial number can be located on the front upper-right corner.

Note:

The MPR number is unique to the game, almost like a serial number.  In multi-ROM games, the MPR numbers are usually one number apart from the other.  For example, DOOM's ROMs are numbered 17252 and 17253, Virtua Racing Deluxe is 17259 & 17260.  Star Wars Arcade is the first game I've seen that breaks this tradition, the ROM numbers are way apart from each other.