We can put banked ROM from 0xC000-0xCFFF, and use that for storing sprite bitmap data.
That means we have two banked regions for graphics ROM: 0xC000-0xCFFF, and 0xE000-0xEFFF. We probably want to bank switch program code, too; so why don't we ignore the /ROML and /ROMH signals completely, decode the address bus directly, and stick "static" ROM from 0x2000-0x9FFF, and banked ROM from 0xA000-0xBFFF?
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