Magnetic drum memory

Along with the Williams_Tube, another early approach to RAM used in 1950s-1960s era of computing.

A magnetic drum was a metal cylinder coated with a magnetic material. Data was stored by magnetising small regions on the drum’s surface. The drum would rotate at high speeds and read/write heads were positioned along the length of the drum to access data.

Seen as a improvement on Williams Tubes and delay line memory but superseded by magnetic core memory later. It’s concept lived on in harddisk drives which became the dominant form of secondary storage.

It had a larger capacity than the technologies that preceded it and it was also non-volatile - the data would remain intact when the power was turned off.

It was used in the IBM 650 (1953) and Ferranti Mark I (1951)