Engines of Our Ingenuity

No. 675: ABACUS II

by John H. Lienhard

Click here for audio of Episode 675.

Tomorrow, I go to honor a change in our way of life. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Tomorrow afternoon I fly up to Dallas. I'm representing The American Society of Mechanical Engineers at a dedication ceremony. We designate historic engineering works as Landmarks.

Last year we dedicated the first windmill in Texas and the first fully air-conditioned building in America. These ceremonies are fun. They remind me how engineering touches our lives.

You expect things like the first windmill and the first air-conditioned building. But many of these machines you might never notice. Tomorrow we dedicate one like that. It's called Abacus II.

That has little to do with the ancient abacus. It's not a gadget that lets you do arithmetic by moving beads on wires. Instead, this is the first machine that automatically made integrated circuits -- the great-grandchildren of the old abacus.

The circuitry for a pocket calculator, or for a computer, is printed out on a chip. It's so small. The calculator on my wrist watch would've filled a room in the radio-tube days of 1950.

The trouble is, you have to connect tiny wires to that tiny circuit chip. You have to communicate with it. How do you weld the wires in place? The wires are gold, only a thousandth of an inch in diameter. You have to place them within a 4000th of an inch. Then you have to melt the gold and bond it in place.

Texas Instruments Company made Abacus to do that in 1970. Abacus used its own computer to weld wires onto an array of chips, automatically.

Two years later, TI made the Abacus II production model. It could weld 375 chips an hour. Later versions did 800 an hour. TI kept making Abacus II for ten years. Then they replaced it with fancier machines.

Abacus II
Abacus II. Image courtesy ASME History & Heritage Committee

Now we go to Dallas to honor a thing that looks like a desk with a computer screen and a microscope on it. You could pass it in the hall without seeing it.

But this Abacus II carries Serial Number One. TI put it to work in Sherman, Texas. Then they sent it to Taiwan -- then Brazil. They did a little upgrading. It has a newer alignment mechanism. But this is where our age of affordable computers began.

It stayed in use for 13 years. This one machine has produced more than fifty million integrated circuits -- fifty million computer brains -- fifty million agents of change. Add the thousand Abacus IIs that followed, and you've completely changed our civilization. Tomorrow, in Dallas, we'll celebrate the way a team of thirteen design engineers altered human history.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


You may read more about the Abacus II, International ASME Landmark in the brochure for the dedication ceremony, March 31, 1992. (write to TI Artifacts Program, MS-233, P.O. Box 655474, Dallas, Texas 75265.)


Scan of this chip courtesy of Special Collections, UH Library

Here is what Abacus II had to attach wires to.
This silicon microchip is 5/16 inch wide, and
it contains over 16 million memory cells.


The Engines of Our Ingenuity is Copyright © 1988-1997 by John H. Lienhard.

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