Another retro graphics demo added

[Bill E]

This one's the classic bouncing ball. It turned out to be far simpler than the cubes, one simple x,y coordinate update per frame, no multiplies, just shifts. And, you can vary gravity via the test switches. It does real acceleration and simulates the elastic rebound with loss, that's a fixed factor but maybe I'll allow changing that also. Another Type340 prog, makes display so much easier (and far faster).

Next up, maybe Sutherland's sketchpad from the tx-2 (I think that's correct). I don't have full details. so I'll have to research that one.

Bill

https://github.com/wjenh/pidp1-mods.git

[Win Heagy]

These graphics demos are very cool and are a great way to show off the machine.  Thanks for the efforts Bill!

Win