The Computer Revolution: From Room-Sized to Pocket-Sized

By Sophia Maddox | January 11, 2024

World's First Electronic General-Purpose Computer Constructed at the University of Pennsylvania

Computers are an integral part of life. People use them to communicate with people who are important to them at work and home. Many people look up information that they want to learn on a computer. Others watch movies, play games or entertain themselves using computers. From early morning to late night, people rely on computer systems to help them stay organized.

While it is hard for most people to imagine life without computers, it hasn't always been that way. Here's a look at how people developed computers and their operating programs. Along the way, meet some people who influenced their development. You'll discover how computers went from filling entire rooms to being small enough to fit in your pocket.


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computer history museum

The United States military commissioned John Mauchly and John Presper Eckert to build a new type of computer in 1943. The pair designed the Electrical Numerical Integrator and Calculator (ENIAC). The computer, constructed at the Moore School at the University of Pennsylvania, was housed in 40 9-foot-tall cabinets. It covered over 1,800 square feet and weighed more than 30 tons, thanks to its 70,000 resistors, 10,000 capacitors, 1,500 relays, 6,000 manual switches and 5 million soldered joints. The university installed two 20-horsepower blowers that constantly blew cold air to keep the machine from melting. It could do 5,000 additions, 357 multiplications, or 38 divisions in one second, but reprogramming the computer to work on a different problem took weeks. In addition, it often needed to be repaired.

University workers eventually dismantled the massive machine, but visitors can see parts of it on the University of Pennsylvania campus and another part at the Smithsonian.

John Backus and Team Forge the First High-Level Programming Language, FORTRAN

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According to John Backus, before his team developed FORTRAN, a computer programmer "had to employ every trick that he could think of to make the program run fast enough to justify the rather enormous cost of running it. And he had to do all of that by his own ingenuity because the only information he really had was the problem at hand, and the machine manual." He also pointed out that, sometimes, there was not even a manual. In addition, many computer programmers considered the information they had amassed highly guarded secrets that they would not share willingly.

In 1957, John Backus was working for IBM when he proposed to his superiors that the company develop a more practical alternative to assembly language that told computers what you wanted them to do. The development of FORTRAN eliminated the need to hand-code computer programs, helping to reduce startup costs. The program became widely accepted and was considered the standard for many decades.