Question about bank switching

[Astralix]

I want to hack some old test gear that uses 4x 27C020 for program space. Two EPROMs are in parallel to get a 16 bit bus. Two are set fixed to the lower ROM address range and the other two are addressed by a latch that select 1 out of for pages using A16 and A17.

Is there a way to make a OneROM 40 USB-C behave like all of those 4 chip at once? And if, what would be the biggest possible memory that could be emulated? Currently the unit "only" uses 4x 27c020 but it mentions optionally 27C080 as well.

[piersfinlayson]

No, I don't think you can do what you want to do with a single One ROM 40. You have 4 x 27C020s to replace = 1MB. One ROM 40 can only serve 512KB (27C400). So you'd need two.

[Astralix]

Thank you for clarifying! I'll order when returning from vacations.