SEGA PART #171-5559-01D

4 Megabit PCB's - Date 1987

These are all 4 Megabit games tied to this PCB.  They are also combined with the 315-5235 Memory Controller (paging chip).  Most 1 and 2 Megabit games have this paging chip contained within the ROMs.  So far, Strider is the only game I've seen to have a 4 Megabit ROM with this controller built into it.  Considering that back when these games were made, mask ROM was very expensive.  To combine this controller chip with the ROM I'm sure adds to the cost.  It may have been cheaper to use the paging chip separately from the 4 Megabit ROM's since there were not a lot of 4 Megabit games made when compared to the number of 1 and 2 Megabit games.  Each ROM has 32 PINs.  The Serial Number can be found on the front, in the upper right-hand corner.