[sjt99]

Exactly, Steve. The board had enough space to put both chips (32Kx8 and E/A GROM) in positions that didn't interfere with the case or the battery holder. I'm still trying to figure out if there is enough real estate available in the right area to switch out the resistor/diode matrix for the battery with an 8-pin DIP that does an even better job at switchovers, but it may be a bridge too far on this one due to space limitations. The battery holder and the 32K chip each chew up a lot of space in that part of the cartridge case. I could probably do it by not socketing the 8-pin chip (a DS1210), but I am a bit loathe to go that route.

Jim,
I had an idea, how to "create" more real estate in the standard cartridge space.
Use the bottom of the board.

I took a quick look and found a holder that is close to 1/4" there may be more out there Mount it on the bottom of the board.

If it works, then there may be more space available to use an electronic switching idea for the different banks (4017 ?) instead of mechanical switches.

See attached