Hi Erik,

I don't read the data sheet the same way, especially when looking at the diagram for the WDT. The interrupt should be independent of the reset, both activated by the timer overflowing (reset activated 512 clocks later than interrupt).

From Dallas DS80C320 Ap Note #80:

The reset and interrupt are completely discrete functions that may be acknowledged or ignored, together or separately for various applications.

At this time I have two pieces of test code, one works, the other doesn't, and the only difference (at the source level) is a data structure that isn't used. After a line-by-line comparison of the listing and map files from my compiler, the only difference is the X_UDATA size and some variable addresses. It's looking like the compiler's startup code isn't running right, like it's depending on some ram to be at a state it isn't on a WDT reset.

So now I'll check out that code real close. If I have to, I'll update the 8051 simulator I wrote awhile back to include the WDT and see where it's actually going.

Erik, I thank you for your time and suggestions!

Dennis