Ultrasonic memory
Maurice Vincent Wilkes · Encyclopedia of Computer Science · 2003
Ultrasonic memories played an important role in the early development of digital computers, but are now only of historical interest. The report on the EDVAC drafted by von Neumann in June 1945 on behalf of the group at the Moore School of Electrical Engineering, Philadelphia, clearly envisaged this type of memory, although it did not describe the physical principles on which it operated. Of the early machines, the EDSAC, SEAC, Pilot ACE, EDVAC, and UNIVAC I all had ultrasonic memories.