Sketchpad

Sketchpad was Ivan Sutherland’s interactive computer graphics system, developed as his 1963 doctoral project. It let users draw and manipulate geometric figures directly on a computer display.

Light pen: A photosensitive input device that detects its position on a display when the display’s beam illuminates it. Sutherland used this pointing device to let users select and draw directly on the screen.
Ivan Sutherland: An American computer scientist whose work helped establish computer graphics and interactive computing. He designed and implemented Sketchpad as his doctoral research project.
Computer graphics: The creation, representation, and manipulation of visual images using computers. Sketchpad demonstrated interactive graphical computing and helped shape the field’s development.
Batch processing: A computing method in which jobs are collected and executed with little or no user interaction during processing. Sketchpad contrasted with batch workflows by letting users change graphics while working.
Constraint-based modeling: A modeling approach in which relationships among geometric objects are specified as constraints. Sketchpad’s constraints let changes to one part of a drawing preserve specified geometric relationships.
Massachusetts Institute of Technology: A private research university in Cambridge, Massachusetts, founded in 1861. Sutherland developed Sketchpad at MIT while completing his doctoral work.
Graphical user interface: A user interface that presents information and controls through visual elements such as windows, icons, and pointers. Sketchpad showed how visual pointing and manipulation could serve as a mode of computer interaction.
Plotter: An output device that draws vector graphics on paper or another physical medium. Unlike a plotter’s fixed paper output, Sketchpad let users inspect and edit drawings on a screen.
Geometric constraint solving: The computation of geometric configurations that satisfy a set of equations or relationships. Sketchpad solved constraints to adjust linked figures after a user changed the drawing.
TX-2: An experimental transistorized computer built at MIT Lincoln Laboratory and operational from 1958. Sketchpad ran on the TX-2, whose display and input hardware supported direct interaction.

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