Editing Selectron tube (section)

== Development ==
Development of Selectron started in 1946 at the behest of [[John von Neumann]] of the [[Institute for Advanced Study]],<ref>Metropolis N, Rajchman, JA (1980) Early Research on Computers at RCA ''A History of Computing in the Twentieth Century'' pp 465-469, {{ISBN|0-12-491650-3}}</ref> who was in the midst of designing the [[IAS machine]] and was looking for a new form of high-speed memory.

RCA's original design concept had a capacity of 4096 [[Bit|bits]], with a planned production of 200 by the end of 1946. They found the device to be much more difficult to build than expected, and they were still not available by the middle of 1948. As development dragged on, the IAS machine was forced to switch to Williams tubes for storage, and the primary customer for Selectron disappeared. RCA lost interest in the design and assigned its engineers to improve televisions<ref name=history/> 

A contract from the [[US Air Force]] led to a re-examination of the device in a 256-bit form. [[Rand Corporation]] took advantage of this project to switch their own IAS machine, the [[JOHNNIAC]], to this new version of the Selectron, using 80 of them to provide 512 40-bit words of main memory. They signed a development contract with RCA to produce enough tubes for their machine at a projected cost of $500 per tube (${{inflation|US|500|1950}} in {{inflation/year|US}}).<ref name=history>Greuenberger JF (1968) [http://www.rand.org/pubs/research_memoranda/RM5654/ ''The History of the JOHNNIAC''] pp 25-27</ref>

Around this time [[IBM]] expressed an interest in the Selectron as well, but this did not lead to additional production. As a result, RCA assigned their engineers to [[color television]] development, and put the Selectron in the hands of "the mothers-in-law of two deserving employees (the Chairman of the Board and the President)."<ref name=history/>

Both the Selectron and the Williams tube were superseded in the market by the compact and cost-effective magnetic-core memory, in the early 1950s. The JOHNNIAC developers had decided to switch to core even before the first Selectron-based version had been completed.<ref name=history/>