Michael Rathbun wrote :

> I know the potential issues with the I/O read/modify/write 
> mechanism in general; I would not have expected it to
> come into play in this situation.

Well, if the code "works" at 4Mhz, but not at 20 Mhz, and you
are using bcf/bsf, I'd say that r-m-w problems would be (at least
one of) the first things to look at.

> In that I found this issue (a visually good but electrically 
> bad connection to VSS at the processor dip socket)...

I'm not sure I've read about *that* problem, but I might have
missed it...

> I'm relatively new to the PIC family, and freely admit to
> being surprised to see a seven-segment LED controller module 
> continue to operate, a bit more dimly, after power was removed.

Getting parasitic power through the protection diodes on the ports.
Can be a *BIG* problem, since you aren't sure that the PIC has
powered down enough to reset properly.

Jan-Erik.



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