) writes:
Interesting, it is a Hitachi 40 pin PIA chip and maybe the Motorolla
part might be easier to source. I have yet to find some place willing
to see just one.

Okay, I risked my neck to get down the Hitachi databook.

The HD6321 is cmos, versus nmos of the 6821. It's supposed to be compatible,
but there might be some cases where it causes a problem. The 6821 should
be easier to get, so it is worth trying.


Michael