The Stored Program

Manchester Small Scale Experimental Machine ("Baby")

This groundbreaking demonstration machine was the first computer to execute a program from memory. Parts of the "Baby" were later incorporated into a larger machine, the Manchester Mark I. The "Baby" was not preserved, but in 1998 a working replica was built and demonstrated for the 50th anniversary of that historic event.

The Stored Program

Even early computers juggled computations with unprecedented speed, but only after a laborious process of setting up programs. This frustrating speed bump became obvious during construction of ENIAC.

Nobody knows who came up with the breakthrough solution: storing in a computer’s memory the instructions that tell it what to do. It was the birth of software, used by every computer since.

The Manchester Baby Breaks New Ground

Fifty-two minutes. That’s how long the experimental Manchester “Baby” ran a 17-instruction program using a “memory tube” devised by Freddy Williams and Tom Kilburn. On June 21st, 1948, the stored-program computer had been born.

By 1949, the Manchester University team had developed a full-scale version: the Manchester Mark I.

Williams-Kilburn Tube - Manchester Mark I

This was one of two storage tubes forming the memory of the Ferranti Mark I computer, successor to the “Baby.” Each tube stored 2,560 bits of information. Such tubes were the first form of electronic random access memory for computers.

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A Universe of Numbers: What is the Stored Program?

This excerpt is taken from the film "A Universe of Numbers," part of the KTEH Public Radio series "The Computer and the Mind of Man." The film is an introduction to data processing, focusing on its role in modern life. Funded by a grant from IBM, it featured the IBM 1620.

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Kilburn Highest Factor Routine

This is the oldest existing documented program for a stored-program computer. It is a version of Tom Kilburn’s highest factor routine that first ran on the Manchester “Baby” on June 21, 1948.

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Tom Kilburn discusses the Manchester Electronic Brain

Chapter Menu

1. The Manchester Electronic Brain
2. Demo Of Baby Replica

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