The PACER memory board has sockets for four MM5204 512×8 EPROMs. The MM5204 is somewhat hard to come by, so I’ve designed a small adapter board to plug into an MM5204 socket and accept a common 2716 EPROM. Only the lowest 1/4 of the 2716 is used.
The schematic and PCB layout of the current version can be seen in this PDF.
The board extends to the side of the MM5204 socket quite a ways, so it won’t be possible to use both pairs of sockets on the PACER memory board. I considered trying to lay it out so that the DIP header on the bottom for the MM5204 would mostly overlap the DIP socket on the top for the 2716, but I was too lazy. Maybe I’ll try that later.
Even better would be to use a surface-mount flash chip, and have some provision for in-circuit programming.