The Concept's boot PROM checks for the signature bytes that exist on the normal Apple II flat cable card (including specific 6502 opcodes, actually). As far as I can tell the one I already emulated for the II/II+/IIe will work fine once I hook up a2bus.
I'd love to read that book, incidentally. The Concept is in some ways a better "68000 Apple II" than Burrell Smith pulled off.
