Help w/ EPROM emulator

[Barry Tisdale]

Does anybody know if there is a 'real-time' PROM emulator out there that I
can use w/ my 7749 ECU (Syclone)?

The emulator vendors I've contacted either have not replied, or not really
answered my questions.

The ECU *will* tolerate switching between PROMs while running via a
thumbwheel switch (Todd A./Brian G. 10/1 chip).

If there's no commercial unit out there that will work, I'd like to put
together a board that will have a 16k generic 'keep-it-running' PROM,
switchable w/ a 16k SRAM which can be loaded &/or modified thru a laptop
parallel port.  I only want to change one byte at a time.  Normally, the
ECU would run using the SRAM; when writing a new byte, it could switch to
the PROM for the few ms needed to write to the SRAM, then switch back to
the SRAM.

I'd rather not reinvent the wheel, so if anybody has done such, or knows of
a commercial unit that will do this, I'd *really* like to know about it.

Thanks - Barry