I contacted the author directly ...

The ASEM51 is integrated with a pretty full-featured simulator/disassembler and an editor that's simple and straightforward, not to mention pretty clearly documented. Unfortunately, it is only capable of simulating 2kB of object code, which means you may have to reallocate the memory you use for a given module under test, but it works well, and has the parameters to simulate quite a wide range of 805x's.

As I mentioned, JSIM, which also works in the MIDE51 IDE, may offer more/better features, but I haven't found 'em necessary.

The doc's are integrated into MIDE51 too, BTW. IF you can get KEIL to work for you, then, now that you've started with it, I'd recommend you stick with it. That's one reason, of many, that I stick with MIDE51 and ASEM-51.

RE