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This tape is from the very
first movie of Sketchpad

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taken in the summer of 1962.

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So this is 25 years old.

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Rubber bands, you're
familiar with.

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But look at what he's doing.

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He's pointing at the
edges and saying,

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I want them to be all
mutually perpendicular.

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And Sketchpad just figured
out how to do that.

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Sketchpad is the first
system to ever have a window.

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He's actually drawing on
a virtual sheet of paper

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about a third of
a mile on a side.

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And, again, to get
something he wants,

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he simply sketches it in
roughly and then gives rules

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like be parallel
and perpendicular,

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and Sketchpad figures out
and solves the problems.

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Here the rule is co-linearity
so that the dashes lie directly

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over the guidelines below.

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Sketchpad was able to solve
very complicated problems

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in real time involving
both linear and nonlinear

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systems of constraints.

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So it was the first
non-procedural programming

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system and considerably
more powerful

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in the spreadsheets of today.

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So he's made a hole in the
flange, continuously zooms

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back.

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Now he wants to make
a rivet, and, again,

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we see why it's
called Sketchpad.

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He just draws a rough shape,
uses the center of the crossbar

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there as the center of the arc.

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And then points to
the edges and says,

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I want these to be mutually
perpendicular again.

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Solving that forces
the crossbar to change

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which forces the arc to
change which gives you

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a perfectly symmetrical rivet.