Hi Craig,

I use this simulator with great success:

http://www.specs.de/~danni/tools/sim51.zip


And I found never any fault or unstable working.

Its also very fast. On my old 100MHz AMD-K5 it works like a real 8051 with the standard 12MHz crystal.

The only disadvantage, the additional SFRs of 8051 derivates can not be simulated.
Also on simulating the Dallas DS80C320 you get not the real count of machine cycles (no way to select an instruction set with different execution time).


Peter