19 Jan
2015
19 Jan
'15
3:22 p.m.
On 19/01/2015 21:45, Diane Bruce wrote:
I'd suspect RAM since the ROM is (I assume) masked
ROM.
The masked ROM could be faulty. My VT100 character generator ROM failed
with one of the data lines floating because (I think) one of the
internal wires had became detached from the die. I replaced it with an
EPROM but had to add a few jumper wires to the legs of the chip to get
the select lines in the right combination.
Matt