I have found a problem with this DLL. I am using the M8051EW. In the debug tab under the options for target menu, the parameters for this dll are -mex -m8051EW. When I have this option selected and I start the debugging process no code shows up in the disassembled window. It is as though there was no code compiled, it is all blank. I have acquired S8051.DLL v3.3.0.1 and that works just fine for me.