Sutherland, I. E. (1963). Sketchpad: A man-machine graphical communication system. MIT.

What matters in this thesis is not the specific system or its implementation but the general mechanisms and paradigms discovered, which influenced so many subsequent systems.

Another key output from this thesis is in distilling the situations where the insights apply: repetitive drawings, as an input device for graph operations (circuit simulations), etc.

Sketchpad makes a key distinction between on-screen objects and the constraints/definitions which are applied to them. (I don’t yet understand the distinction between constraints and definitions, though Sutherland says that “copying definitions” (along with “recursive merging”) are the most important contributions of his system).

Q. When was the Sketchpad thesis published?
A. 1963.

Q. How might you make a hexagon in Sketchpad?
A. Make six lines with attached vertices, attach each vertex to a circle, copy one line’s definition to the others to make them the same length.

Q. How long did Sutherland take to get an initial prototype of Sketchpad running?
A. About 3 months.

Q. How long did Sutherland take between starting on Sketchpad and implementing the final iteration?
A. About a year.