2600 Flash Cart / Multi-Cart Comparison Matrix

[bigmessowires]

Right, that's why you need the OR circuit to drive some of the address bits onto the data bus.

 

EDIT: At any address, the 6507 will see the data byte 0 1 0 (A1 or A0) 1 1 0 0. So the memory map will look like this:

 

5C4C: 4C

5C4D: 5C

5C4E: 5C

...

5C5C: 4C

5C5D: 5C

5C5E: 5C

...

FFFC: 4C

FFFD: 5C

Edited January 28 by bigmessowires

[+batari]

5 hours ago, Ben_Larson said:

I've probably been staring at old arcade schematics for too long but it seems like something like this might be solvable in hardware by tying an address line to a bus transceiver to disconnect the ARM when the 6507 is accessing RAM/TIA space.

 

I'm not even sure if we're talking about existing hardware or new hardware at this point, though. 

I suggested something like that in another thread. It could work