Selectron tubes. Computer information storage tubes (valves) on the Johnniac mainframe computer, which is housed at the Computer History Museum, California, USA. The Johnniac was based on a design by John von Neumann at the Institute for Advanced Study, Princeton, USA. It went into operation in 1953, using 80 Selectron tubes that held 256 bits of data and cost $500 each. In 1955, the tubes were replaced by the first commercially built core storage. Johnniac was decommissioned in 1966, having logged 50,000 operational hours. The museum has over 3000 artefacts from 1945 to 1990. It is due to be relocated, becoming part of the NASA Research Park, California, USA, in 2005.