Sketchpad
A program that allowed users to draw on a screen with a {light
pen}. It supported constraints (e.g. drawing a constrained
ellipse produced a circle). It also had some {computer aided
design} features (e.g. computing loads on beams).
Sketchpad was the subject of {Ivan E. Sutherland}'s 1963 {MIT}
PhD thesis, which opened the field of {computer graphics}. It
was the progenitor of computer drawing packages like {MacDraw}
or {Adobe Illustrator}. There is a film of Sketchpad in
action.
It solved {constraints} using {value inference} and introduced
the "{ring}" list structure.
["Sketchpad: A Man-Machine Graphical Communication System",
I.e. Sutherland, MIT Lincoln Lab, TR 296 (Jan 1963)].
[Sammet 1969, p. 678].
(1995-02-14)