William Shockley, John Bardeen and Walter Brattain at Bell Labs invented the first working transistor, the point-contact transistor, in 1947, followed by the bipolar junction transistor in 1948. At the University of Manchester in 1953, a team under the leadership of Tom Kilburn designed and built the first transistorized computer, called the Transistor Computer, a machine using the newly developed transistors instead of valves. The first stored-program transistor computer was the ETL Mark III, developed by Japan's Electrotechnical Laboratory from 1954 to 1956. However, early junction transistors were relatively bulky devices that were difficult to manufacture on a mass-production basis, which limited them to a number of specialised applications.