Ferranti Mercury facts for kids

The Mercury was an important early computer built by a company called Ferranti in the mid-1950s. It was designed to be better than their previous computer, the Ferranti Mark 1. The Mercury was faster and more dependable.

It got faster by adding a special part called a floating point unit, which is great for math. It became more reliable by using a new type of memory called core memory instead of older Williams tubes. It also used more modern electronic parts. The Mercury computer had about 2,000 vacuum tubes and 2,000 germanium diodes. Ferranti sold 19 of these computers before making even newer designs.

The Mark I: Mercury's Older Sibling

The Ferranti Mark 1 computer started working in 1951. But it often had problems. Its main memory system, which used a drum memory, broke down a lot. Also, the Mark 1 used 4,200 vacuum tubes, which are like old-fashioned light bulbs. These tubes often stopped working and needed to be replaced all the time.

Another part, called Williams tubes, was used for temporary memory. These also needed constant care to keep them running. Because of these issues, engineers quickly started looking for ways to make computers more reliable.

One group of engineers tried to build a much smaller and cheaper computer. They wanted to use new parts called transistors instead of tubes. Their first transistor computer ran in 1953. It was one of the very first computers made completely with transistors.

Meet Meg: The Test Computer

Another team of engineers, who helped design the Mark 1, started working on a new computer. It was similar to the Mark 1 but used solid-state diodes instead of vacuum tubes for some parts. These new diodes were much cheaper than transistors. Using them made the computer simpler and more reliable.

At that time, computers were mostly used for science. So, the team decided to add a floating-point unit. This part made the computer much better at handling complex numbers and calculations. They also wanted the new machine to run much faster. It was designed to be eight times quicker than the Mark 1. Because it ran at 1 MHz (one million cycles per second), they called it the "megacycle machine," which later became "Meg."

The Meg computer first worked in May 1954. By using solid-state diodes, they cut the number of vacuum tubes by more than half. This also meant the computer used much less power. The Mark 1 used 25,000 watts, but Meg only used 12,000 watts.

Meg could multiply two numbers in about 60 microseconds. Its floating-point unit could add two numbers in about 180 microseconds and multiply them in about 360 microseconds. That was very fast for the 1950s!

Mercury: Ready for Business

Ferranti, the company that built the Mark 1, kept working on the Meg prototype to create the Mercury computer. The biggest change was replacing the Williams tubes with core memory. Core memory was a bit slower, but it hardly needed any maintenance. This was very important for businesses and universities using the computers every day.

The first of 19 Mercury computers was delivered in August 1957. The University of Manchester received one in February 1958. They even leased it out to other companies through Ferranti. Big science organizations like CERN in Switzerland and the Atomic Energy Research Establishment in the UK also got Mercury computers in 1958. The UK's weather office, the Met Office, bought a Mercury in 1959. Even the University of Buenos Aires in Argentina received one in 1960.

The Mercury could run a special coding system called Mercury Autocode. This was a simpler way to write computer programs, much like the high-level programming languages we use today. The Mercury computer weighed about 2,500 pounds (1,134 kilograms).

See also

• Manchester computers
• List of vacuum tube computers