30 Jun
1999
30 Jun
'99
3:26 p.m.
They're not equivalent, though they share the same
pinout and
function with the old National Semiconductor 8097. The 8T97
has greater current source/sink capability, hence it is faster
in some applications and can drive a pretty stubstantial load.
It was very common as a bus driver, which was it's intended
purpose. For normal TTL fanout, either part will work.
Well, an 8T97 was specified for U24 on the CP-A. U24 had been
socketed and replaced with a 74367. I "undid" the mods around
U24/U25 and populated U24 with an 8T97. A bunch of work, no
change in behavior. Arg!
I also looked at the MPU-A. Sure enough, on the 16 pin header
to the front panel, pins 1-8 are connected to pins D0-D7 on
the 8080, in order (pin1-D0, pin2-D1, etc). They also go a
bunch of other places I have not tried to figure out yet. It's
probably just going to the data lines on the S-100 connector.
Given the C3 instruction, I don't see why everything goes so
wacky when I reverse the header.
I've looked through the docs I got with it and don't have
anything on the MPU-A.