Fully ROM/Flash PC-ish systems are/were pretty common in the embedded and industrial control space. Usually the boards emulate one or more floppy drives. I've

Fully ROM/Flash PC-ish systems are/were pretty common in the embedded and industrial control space. Usually the boards emulate one or more floppy drives. I've got a half dozen variations, including PROM, Flash and battery backed SRAM. Even one with bubble memory, which is pretty nifty. The first-gen PIX you mention had an 8M or 16M ISA flash card it booted from, containing the whole OS. The Novell netboot is called "RPL".