The First Generation (1945-55) Vacuum Tubes

The First Generation (1945-55) Vacuum Tubes

After Babbage's fruitless efforts, little progress was made in constructing digital computers until World War II, which motivated an explosion of activity. Prof. John Atanasoff and his graduate student Clifford Berry built what is now regarded as the first functioning digital computer at Iowa State University. It used 300 vacuum tubes. At about the same time, Komad Zuse in Berlin built the Z3 computer out of relays. In 1944, the Colossus was built by a group at Bletchley Park, England, the Mark I was built by Howard Aiken at Harvard, and the ENIAC was built by William Mauchley and his graduate student J. Presper Eckert at the University of Pennsylvania. Some were binary, some used vacuum tubes, some were programmable, but all were very primal and took seconds to perform even the simplest calculation.

In these early days, a single group of people (normally engineers) designed, built, programmed, operated, and maintained each machine. All programming was done in absolute machine language, or even worse yet, by wiring up electrical circuits by connecting thousands of cables to plugboards to control the machine's basic functions. Programming languages were unknown (even assembly language was unknown). Operating systems were unheard of. The common mode of operation was for the programmer to sign up for a block of time using the signup sheet on the wall, then come down to the machine room, put in his or her plugboard into the computer, and spend the next few hours hoping that none of the 20,000 or so vacuum tubes would burn out during the run. Almost all the problems were simple straightforward numerical calculations, such as grinding out tables of sines, cosines, and logarithms.

By the early 1950s, the routine had improved to some extent with the introduction of punched cards. It was now possible to write programs on cards and read them in instead of using plugboards; otherwise, the procedure was the same.


operating system, vacuum tubes, digital computer