This tape is from the very first movie of Sketchpad
taken in the summer of 1962.
So this is 25 years old.
Rubber bands, you're familiar with.
But look at what he's doing.
He's pointing at the edges and saying,
I want them to be all mutually perpendicular.
And Sketchpad just figured out how to do that.
Sketchpad is the first system to ever have a window.
He's actually drawing on a virtual sheet of paper
about a third of a mile on a side.
And, again, to get something he wants,
he simply sketches it in roughly and then gives rules
like be parallel and perpendicular,
and Sketchpad figures out and solves the problems.
Here the rule is co-linearity so that the dashes lie directly
over the guidelines below.
Sketchpad was able to solve very complicated problems
in real time involving both linear and nonlinear
systems of constraints.
So it was the first non-procedural programming
system and considerably more powerful
in the spreadsheets of today.
So he's made a hole in the flange, continuously zooms
back.
Now he wants to make a rivet, and, again,
we see why it's called Sketchpad.
He just draws a rough shape, uses the center of the crossbar
there as the center of the arc.
And then points to the edges and says,
I want these to be mutually perpendicular again.
Solving that forces the crossbar to change
which forces the arc to change which gives you
a perfectly symmetrical rivet.