I made a couple changes to the drawing. Stacks and register structures are now a bit more conceptual -- it is much easier to see how they work.
See <http://www.msen.com/~fox/parrotguts.png> for the latest. Keep in mind that the light blue "frame" stuff at the bottom is experimental. Anybody interested in a version useful for hand simulation? I'm pretty sure that gluing a picture to foam core board would be a pretty good tool for simulating Parrot. Gotta love low tech push pins and string... ;) - Ken
