Max Sentry wrote:
> Gordon- Thanks for the reply. But actually, I have original 727 voice
> chips (pulled from 727)that I want to install along with the existing
> 707 ones. I have no prommer.
Ok, then you need a slightly different approach. Piggyback the ROMS
soldering all the legs together (maybe use a socket for this - spread
its legs a bit and solder it to the existing ROM). Now find the /CE pin
for the chip. Usually it will be held permanently low, to always enable
the output. disconnect it, fit a pull-up resistor as I described
before, and use the switch to pull it to ground to enable that ROM.
If you find that both /CE and /OE (output enable, another possibility)
are driven by other bits of clever circuitry, you'll need to use some
kind of gate to switch the enable pulses. I'll try and get a look at
the circuit diagram over the weekend and come up with a more detailed
description.
Gordon