Page "Computer memory" Paragraph 7

Two alternatives to the delay line, the Williams tube and Selectron tube, originated in 1946, both using electron beams in glass tubes as means of storage.

Using cathode ray tubes, Fred Williams would invent the Williams tube, which would be the first random access computer memory.

The Williams tube would prove more capacious than the Selectron tube ( the Selectron was limited to 256 bits, while the Williams tube could store thousands ) and less expensive.

The Williams tube would nevertheless prove to be frustratingly sensitive to environmental disturbances.