Selectron tube

Jan Rajchman started work at RCA in 1946 on a tube that held charge at individually addressed points rather than as spots on a swept raster image. On paper it was the better technology: addressing was direct instead of positional, and the design was meant to hold 4096 bits per tube. On the strength of that promise, von Neumann specified forty Selectrons for the IAS machine.

The promise did not survive manufacturing. The large version could not be produced at any acceptable yield, and when RCA finally shipped in 1948 it was a 256-bit part at roughly $500 apiece. Princeton gave up and took Williams tubes instead, which were built from ordinary oscilloscope tubes available off the shelf.

The only machine that ever ran on Selectrons was RAND's JOHNNIAC, with eighty of them. Magnetic core memory then arrived and made the entire electrostatic family obsolete within a couple of years — the standard cause of death for technology that is somewhat better and several years late.