A program that allowed users to draw on a screen with a
lightpen. It supported constraints (e.g. drawing a constrained
ellipse produced a circle). It also had some
computer aideddesign features (e.g. computing loads on beams).
was the progenitor of computer drawing packages like
MacDrawaction.
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)