Fifty years ago saw the birth of the world's first commercial computer. The 15-ton behemoth, called Univac 1 and built by the predecessor of Unisys, has watched over the explosive growth of the ubiquitous beige box.

Univac 1 (Universal Automatic Computer) celebrated its 50th birthday on Thursday. On June 14, 1951, Univac 1 made its debut at the US Census Bureau, the first enterprise customer in an industry that has grown to become a multibillion dollar market. It was shown off back then during a ceremony to celebrate "the fact that it was installed and ready to go", said Steve Holzman, a Unisys spokesman.

For a hefty price tag of $1.6m the Census Bureau invested in the computer, which could hold a maximum 12MB of data, had a processing speed of 0.008MHz and required 952 cubic feet of space in which to live, about the size of a Land Rover.

In comparison, Unisys' latest enterprise computer, the ES 7000, holds thousands of gigabytes of data, has 32 processors running at 900Mhz each and is no bigger than an average-sized refrigerator.

The original machine was so big, in fact, a door opened up to its core where engineers would often install a desk and chair inside to enjoy the computer's air-conditioned centre.

Despite its size, the machine soon became a sought-after device for computing thousands of equations per second. One of its earliest customers, General Electric, used the Univac to do its payroll. In its first few years in production, 46 customers from the US Army to DuPont employed the lumbering giant to run their own systems.

Univac's creators also built the Eniac (Electrical Numerical Integrator And Calculator) in the late 1940s as the predecessor to the Univac. The Eniac was developed by John Mauchly and John Presper Eckert for a US military project known as Project PX to calculate the trajectory of artillery shells during the second World War. The machine they built was twice as large and possessed half the calculating speed of the Univac, Unisys said.

"There were a lot of electromechanical technologies that did faster computations than you could do with a piece of paper," Holzman said of the time. "The Eniac was the first fully electronic machine."

But Eniac's creators quickly improved the performance of their first machine and by 1951 created a computer that would be sold to corporate customers besides the US government. Over the years, through a maze of corporate buyouts and acquisitions, the Univac found a home at Unisys in 1986.

The company now has a lot to reminisce about. Unisys issued an "apology" on Thursday for introducing the Univac to the enterprise market. The company said it was sorry for "giving Spam a bad name", jokingly referring to the meat product whose name came also to mean unsolicited commercial email.

Unisys further offered a tongue-in-cheek apology for paving the way for the dotcom bubble, its subsequent burst and the elimination of the concept of regular working hours.

But what the machine might be best remembered for is the first computation that gave it widespread public attention. In 1952 the Univac correctly predicted that Dwight D Eisenhower would be victorious in the US presidential election.

Guardedly, CBS's evening news show chose not to air the Univac prediction, instead waiting for an official count. Soon after the polls closed, CBS anchor Walter Cronkite acknowledged its accuracy.

If only reporters had shared a similar scepticism for early predictions in the last US presidential election, George W Bush... no, Al Gore... no, George W Bush could have been more comfortable celebrating an early victory.