Johnniac mainframe computer, housed at the Computer History Museum, California, USA. The Johnniac, based on a machine by John von Neumann, was built at the Institute for Advanced Study, Princeton, USA. It went into operation in 1953, using Selectron tubes (valves) as its storage method. In 1955, the Selectron tubes were replaced by the first commercially built core storage. Johnniac was decommissioned in 1966, having logged 50,000 operational hours. The Computer History Museum's collection includes over 3000 artefacts from 1945 to 1990. It was established in 1996 and is due to be relocated, becoming part of the NASA Research Park, California, USA, in 2005.