10 Jun
2005
10 Jun
'05
4:48 p.m.
All:
With my two new machines I want to get a PROM monitor in them so
I can start really playing around with them. I have a single Vector RAM/PROM
III board, which uses 2704 or 2708 EPROMS. Most of the chips I have are 2732
or larger.
Before I go slogging through the manual to try to hammer a 4k
chip into a 1k socket, does anyone have any experience making this mod?
It's not that hard to do (I've done it on other boards). The main thing
to watch for is that the 2708 used 3 supply rails (+5, -5, +12), the
later EPROMs are single-supply. IF you don't disconnect the -5 and +12
rails, you'll ruin your 2732...
Most of the pins match up (the address and data pins, for example). It's
just a matter of fiddling about 4 pins between pin 18 and 21 IIRC. You
should probanly tie the A10 and A11 pins of your 2732 either high or low,
and burn the ROM image into the right quarter of the chip.
It's fairly easy, using a bit of stripboard, a couple of header plugs,
and a DIL socket, to make up an adapter board to do this without
modifying the original PCB.
-tony