[Simh] SLowing up simh

[Sterling Garwood]

is there a way to slow down the simulation? I am running PDP11  
simulations using RSTS and RT-11 and the simulator never seems to  
drop into a real wait state (my real processor stays pegged out even  
if nothing is going on in RT-11). Since I am running on Mac OS X on  
an iBook I'd like to trade off simulation speed for battery life and  
less heat. I have a 1.3 GHz laptop so a bit of a slow up of simh  
wouldn't be too bad :-). My assumption is that either (or both) RSTS  
and RT-11 actually use a wait state.
I looked at the code and thought about putting a nanosleep just  
before IFetch but I thought I'd ask before I do that.