Thanks for your help, but I meant a FREE Simulator

You get what you pay for. The simulator mentioned by Steve is free up to 2k. If you need the full 64k a $25 investment is all it takes. I can understand some hesitance in purchasing multi-thousand dollar development systems, but $25 is only about, what, 5 microcontrollers when purchased individually? Hardly a large investment.

Open source is great. But sometimes the best tool for the job costs some money and you're going to lose more money (i.e. time) by insisting on a "free" alternative than just spending a few bucks and being done with.

Just my opinion.

Regards,
Craig Steiner