Tony Duell wrote:
Silly random thought. IIRC, there's an empty 40 pin
DIL socket on the ACW
coprocessor board, and I think it's on the 32016 sencond processor board
too (I must come and collect that from you). Wasn't that for an MMU chip?
Yep, you're right (about there being empty sockets on both versions of
the board). I suppose it's logical it'd be an MMU chip given that
there's no other connectors to the board (e.g. it's not for an optional
serial chip or whatever).
I've checked my ACW schematics, and it is for an 32082 MMU chip.
Funnily enough, mention of that socket just cropped up on the BBC list,
and someone remembers their father working on one of these boards with a
floating point unit fitted into that socket via a small daughtercard.
They're willing to admit that they may be misremembering though!
Would that be a possibility though, or is it definitely an MMU socket?
The scoket is certainly for an MMU chip (32082). It's the right pinout
for that. I seem to rememebr there's some timing-fix PROM/PAL that goes
with it, but I can't be sure (and I certainly don't have the contents of
said device)
That said, I think it would have been possible to make a daughterboard
with the FPU chip (32081 IIRC) on it. There may have been the odd extra
signal you'd have to pick up with a kludgewire, but most of the ones you
need are on that socket. So the story you heard might well have been true.
-tony