The UK’s national museum of computing has restored a 61-year-old computer to full clacking, blinking, and punch-card-reading working order. It’s noisy and, as you can see in the video below, it’s awesome.

The computational machine is a 5500-pound monstrosity with 828 Dekatron valves — think old-fashioned RAM in which you can actually see the process of memory storage — 480 relays, which are electromagnetic switches, and 199 lamps, which blink on and off as the computer runs its calculations. Programs are input via punch cards, and results are outputted to a teleprinter — sort of like an old-fashioned typewriter.

Above: A dekatron valve

Image Credit: The National Museum of Computing

The Harwell Dekatron computer was used for atomic energy research, automating calculations that previously had to be performed by hand. Interestingly, it was a decimal computer, not binary.

Although very slow — it took five to ten seconds to multiply two numbers — it was also very reliable, running an average of 80 hours a week and once, according to Wikipedia, running for ten days straight over a Christmas/New Year’s holiday.

“In 1951 the Harwell Dekatron was one of perhaps a dozen computers in the world, and since then it has led a charmed life surviving intact while its contemporaries were recycled or destroyed,” museum trustee Kevin Murrell said.

Check out this 50-second video — the Dekatron sounds more like a printing press than a computer:

The Harwell Dekatron was used until 1957, at which point it was given to the Wolverhampton and Staffordshire Technical College, which used it to help educate students until 1973. After going on display temporarily in a museum, being dismantled, and stored, it was discovered by volunteers from the National Museum of Computing four years ago.

The machine is now on display at the museum.

Image credits: The National Museum of Computing