So far, we've been able to find the device codes
for
updating the 7-segment LED displays on the front, turning on and off
relays, and setting some arbitrary open-collector outputs.
Do you mean the seven segment displays on the paper tape reader?
There are three 512-by-4 bipolar (configured as
512-by-12) PROMs that seem
to override the core memory at the top of the 4k field. If the PROM's value
is 7777 octal, the core memory is accessible. Otherwise, you're stuck with
ROM, best I can tell.
So if you jam the PROMs output to 7777 for any address, you can get to
all the core (and make the machine useful)?
The source for the PROM may be with that CD I gave to Al.
--
Will