Do you know the chip numbers and/or specs for the ROMs
you wish to
emulate?
Personally, I'd like to have something with a ROM interface on one side
(and probably EEPROM onboard), with a serial interface so the contents
can be changed, preferably live. I built such a thing once on a
breadboard; I wired it in in place of the character-generator ROM of an
ascii terminal (a TVI955). The wiring was not up to the frequencies
required, but fortunately, it being just the character generator, all
that happened was snow on the screen. But it _was_ cool to be able to
download new character glyphs live. :-)
The devices I'd most want to do this with at the moment are 27256s. I
suppose I should just build/buy a conventional EPROM programmer; 27256s
(and even 28256s) are not all that scarce last I looked.
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