“We shall now consider how we can design a very simple machine that will think..”

Simon was the first personal computer.

Edmund Berkeley developed it and presented it for educational purposes in a series of thirteen construction articles in Radio-Electronics magazine, from October 1950. There were far more advanced machines at the time, but the Simon was the first automatic simple digital computer that average individuals could afford. In 1950, it sold for US$600.

giant brains

Giant Brains, or Machines That Think .1949.

“We shall now consider how we can design a very simple machine that will think.. Let us call it Simon, because of its predecessor, Simple Simon… Simon is so simple and so small in fact that it could be built to fill up less space than a grocery-store box; about four cubic feet….It may seem that a simple model of a mechanical brain like Simon is of no great practical use. On the contrary, Simon has the same use in instruction as a set of simple chemical experiments has: to stimulate thinking and understanding, and to produce training and skill. A training course on mechanical brains could very well include the construction of a simple model mechanical brain, as an exercise.”


Simple Simon for Scientific American magazine. November 1950

“possessed the two unique properties that define any true mechanical brain: it can transfer information automatically from any one of its “registers” to any other, and it can perform reasoning operations of indefinite length.” pag 40


“Some day we may even have small computers in our homes, drawing their energy from electric-power lines like refrigerators or radios … They may recall facts for us that we would have trouble remembering. They may calculate accounts and income taxes. Schoolboys with homework may seek their help. They may even run through and list combinations of possibilities that we need to consider in making important decisions. We may find the future full of mechanical brains working about us..”

The Simon’s architecture was based on relays.

The programs ran from a standard paper tape, with five rows of holes for data.

The registers and ALU stored only 2 bits.

The user entered data via punched paper, or by five keys on the front panel.

The machine output data through five lamps.

The punched tape served not only for data entry, but also as memory storage.

The machine executed instructions in sequence, as it read them from the tape.

It could perform four operations: addition, negation, greater than, and selection.


In 1950 Berkeley founded, published and edited a journal, which was developed in 1951 to the Computers and Automation, thought to be the first computer magazine.

Later Berkeley designed and sold several other simple calculating devices—Geniac (Genius Almost-Automatic Computer) (see the lower image), Tyniac (Tiny Almost-Automatic Computer), Weeniac (Weeny Almost-Automatic Computer), Brainiac (Brain-Imitating Almost-Automatic Computer). ( from http://history-computer.com/ModernComputer/Personal/Simon.html)

World’s Smallest Electric Brain

Small Robots Report