Simple Simon, world's smallest mechanical brain, visits Seattle on June 20, 1950.

  • By David Wilma
  • Posted 3/22/2000
  • Essay 2490

On June 20, 1950, Simple Simon, the world's smallest "mechanical brain" visits Seattle as part of the American Society of Engineering Education convention at the University of Washington. Weighing 39 pounds and measuring 24 inches long, 15 inches wide, and 6 inches tall, Simple Simon is more "feeble minded" than its larger relatives. Simple Simon can use four digits and can hold 16 numbers at a time. It cost $540 to build this ancestor of today's computers.

Dr. Ned L. Reglein transported the device from Harvard University to demonstrate "giant computers" which can handle 5,000 problems a second involving figures up to 351,000,000 digits.

Wrestling With Addition

The Seattle Times described Simon in action:

"Here's how it works: Reglein feeds a perforated tape containing a mathematical problem into Simon's "mouth."

The problem today was to first add 2 and 1, then find the negative of 3, which is 1. Next, find which of these two results is the greater. (1.) After that, select "2" if the first result is greater than the second. (2.) Simple, what?"

In went the tape. Simon's life blood, 24 volts of A.C. current, flooded through his insulated veins. The brain's mechanism made a ratchety sound as it wrestled with the addition of "2 and 1." Finally, Simon blinked his lights to indicate "3" and relief swept over Dr. Reglein's features.

"Right!" he shouted exultantly.


The Seattle Times, June 20, 1950, p. 8.

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