Hyperball is 3x2532 roms. I don't think it's easy to modify the system 7 board to use 2732's in all 3 positions though, it's actually what spurred me to acquire the 2532 eproms (and build an accompanying adapter for the tl866) as I needed to burn this for a project that needed the largest romspace available on system 7.

That's not to say it couldn't be done (you certainly could jumper for 3x2532 and put adapters on the eproms themselves to use 2732's) - but the factory jumpers don't have the 2732x3 config.

That's (and others from that site) are on my list of things to get and try. My stock of 2532/2732 are dwindling ... I guess I can't expect 40 year old eproms to be able to erase and reburn continuously, after all. Time to get adapters to go into my 30 year old 128 and 256 chips.

Yeah, no kidding. And I have the BK precision one that does like 40 at a time. Since going to the 512 eeprom I've been using those exclusively even when I'm putting it in a 128 or 256.... after I'm through hacking around I might burn it onto the eprom to get the 512 back. I have had a couple of the 512's go bad but when I say reuse.... I mean 100's of times. For flight 2000 I know I burned at least 1000 versions tweaking it, so those 512's got a real workout.

I would love adapter boards that fit into the original mpu's (system 11/9) that replace the 2 eproms with 1 512.... I played around with this a little bit but because my hardware skills suck, it didn't work. Should have been pretty straightforward I'd thought, using the existing chip enables on u26/27 into a gate to select the 512 on the adapter board, but nope.... no go.

Ditto with a system 7 kahout board, obviously something I'm missing. Only thing I've been able to do is hack the siegecraft system 6 adapter to work on bally/stern boards but your replacement mpu eliminated me requiring that.