The WITCH is back . Of course , if you 're a computer historian , you already know that WITCH refers to the Wolverhampton Instrument for Teaching Computation from Harwell . If not , here 's the story : The 2.5-ton machine , first constructed in the 1950s as part of an atomic research program , became the `` world 's oldest original working digital computer '' after a museum in the UK restored and then rebooted it on Tuesday . Unlike today 's nearly mute devices , the massive computer clicks , clacks and flashes like something out of an old sci-fi movie . `` In 1951 the Harwell Dekatron ( the other , less-amazing name for the WITCH ) 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 , '' Kevin Murrell , a trustee at the UK 's National Museum of Computing , said in a news release . The computer outlived its usefulness in atomic research by 1957 and was used as a teaching device until 1973 . It went on display briefly before being dismantled , the museum says , and then was `` rediscovered '' by volunteers at the museum in 2008 or 2009 . The computer 's `` flashing lights and clattering printers and readers provides an awe-inspiring display for visiting school groups and the general public keen to learn about our rich computer heritage , '' the museum says . It 's also a healthy reminder that not all gadgets have to die after a single product cycle . At a time when iPhones are swapped out every 12 months , the TI-83 calculator and this computer are among the only pieces of technological machinery that have survived for decades . The WITCH , however , does n't serve much of a practical purpose at this point . `` All together , the machine can store 90 numbers . The closest analogy is a man with a pocket calculator , '' Delwyn Holroyd , who led the restoration effort , tells the BBC in a video about the restoration ( you should watch the video , by the way , if for no other reason that to see this thing in action ; it sounds like a broken typewriter as it works ) . `` However , unlike the man with a pocket calculator , this machine can carry on day and night , and it does n't make mistakes . '' Modern computers store information in binary code , or a system of 1s and 0s . The WITCH , by contrast , features walls of dekatron valves , which are little light-bulb-looking things . It counts on a 10-digit decimal system . `` All told , the WITCH had 40 banks of 8 dekatrons , meaning it could store up to 40 8-digit numbers , '' Sebastian Anthony writes for the website ExtremeTech . `` The computational processes themselves , carried out by relays , was very slow -- somewhere on the order of 5 or 10 seconds to multiply two numbers . '' Another drawback : The WITCH reads computer programs from paper tape with holes punched in it . The computer `` does n't have a keyboard or a monitor like a modern machine , '' Holroyd explains in an ITV video . Perhaps the machine is so mesmerizing because , in a way , you can see how it works . Modern computers -- much less the Internet or smartphones -- are largely silent , glowing devices . They seem powered by wizardry . The WITCH , by contrast , is a clacking , blinking , ticking mess of mechanical parts . `` To see it in action is to watch the inner workings of a computer -- something that is impossible on the machines of today , '' Murrell , from the museum , says in the news release . `` The restoration has been in full public view and even before it was working again the interest from the public was enormous . '' If you want to see the machine for yourself , it 's on display at the National Museum of Computing in Buckinghamshire , north of London . It 's located on the Bletchley Park estate , which was home to England 's codebreakers during World War II .
The `` world 's oldest original working digital computer '' gets a reboot . The WITCH is now operational at a museum in the UK . The computer , created for atomic research , was restored over three years . It has the computing power of `` a man with a pocket calculator ''