Blinding fast PDP-11 Simulator

I found another PDP-11 simulator on the web that is orders of magnitudes faster than Bob Supnik's simulator. You can find it at http://www.dbit.com (it's called ersatz11). They sell it commercially, but it is free for personal use. It runs under DOS and Windows 95. This simulator runs on my 200 Mhz Pentium as fast as a real PDP-11/70, possibly faster. It also has some nice features, such as it picks up the date and time automatically from DOS. So when you boot RSTS you don't need to keep entering the date and time. It also seems to recognize more memory than Bob's simulator. RSTS never seems to recognize more than 124K under Bob's simulator, but on ersatz11 RSTS recognized up to 300K. I think it also use real-time clock interrupts to generate the simulated interrupts.