zlacker

>>fs_sof+(OP)
Sutherland figured out how graphic interaction ought to work, with the computer recognizing near points and connecting them. What we now call "snap". He had the key idea of CAD - you can draw with more accuracy if the computer helps.

That demo is running on the MIT TX-0, a transistorized version of Whirlwind and the predecessor of the PDP-1. It was somewhat obsolete at that point, so projects like this could get time on it.

>>Animat+phb
Constraints as well, you can hear him talking about them at 8:20, this is fundamental to CAD programs.

>>ulnark+bOb
The company I worked for in the early 80’s was in the market for a CAD system, and they all had constraint systems in the UI, and showed them in the demos.