digital circuit simulator

[Marty Billingsley]

Hi --

Anyone know of a digital circuit simulator implemented in RR?  I'd  
like my students to be able to drag logic gates around, hook them to  
inputs, put power to the inputs, and see what the output is.  An  
applet example of what I'm looking for can be found at <http:// 
math.hws.edu/TMCM/java/labs/xLogicCircuitsLab1.html>

If one doesn't exist in RR, I may try writing one....but it won't be  
in time for this year's students to use. :-)

Any pointers, either to an existing program, or to how I might  
approach this using RR?

Thanks,
   - marty

--
Marty Billingsley
The University of Chicago Laboratory Schools