50th anniversary of the UNIVAC I

UNIVAC I was the first computer to be widely used for commercial purposes -- 46 machines were built, for about $1 million each

BLUE BELL, Pennsylvania (CNN) -- Fifty years ago -- on June 14, 1951 -- the U.S. Census Bureau officially put into service what it calls the world's first commercial computer, known as UNIVAC I.

UNIVAC stands for Universal Automatic Computer. The first model was built by the Eckert-Mauchly Computer Corp., which was purchased by Remington Rand shortly before the UNIVAC went on sale.

Rights to the UNIVAC name are currently held by Unisys.

Unisys spokesmen Guy Isnous and Ron Smith say other early users of UNIVACs included the U.S. Air Force, the U.S. Army, the Atomic Energy Commission, General Electric, Metropolitan Life, US Steel, and DuPont.

The UNIVAC was not the first computer ever built. A host of companies, including Eckert-Mauchly, Remington Rand, IBM, and others, all were developing computers for commercial applications at the same time.

Perhaps the most famous computer of the era was the ENIAC, a computer developed for the U.S. military during World War II. Other computers developed in the 1940s were mostly used by academia.

But the UNIVAC I was the first computer to be widely used for commercial purposes -- 46 machines were built, for about $1 million each.

Compared to other computers of the era, the UNIVAC I machines were small -- about the size of a one-car garage. Each contained about 5,000 vacuum tubes, all of which had to be easily accessible for replacement because they burned out frequently.

Keeping all those vacuum tubes cool was also a major design challenge. The machines were riddled with pipes that circulated cold water to keep the temperature down.

Each unit was so bulky and needed so much maintenance that some of the companies that bought them never moved them to their own facility, instead leaving them on-site at Remington Rand.

UNIVAC I came to the public's attention in 1952, when CBS used one to predict the outcome of the presidential election. The computer correctly predicted the Eisenhower victory, but CBS did not release that information until after the election because the race was thought to be close.