Magnetic drum computers of the 1950s

We were cataloging text materials recently at the Computer History Museum and came across documents describing some early computers from the 1950s. These machines were being sold during the time when “small” machines used magnetic drums as memory. A few years later this type of memory was replaced in the market with core memories.

Elecom 120 computer
Elecom 120 computer

The Elecom 120 computer was sold by Underwood. Its magnetic drum memory contained storage for 1000 words of memory with an access time of 20 milliseconds. Programs for the machine were written in machine language. The Elecom could also attach paper tape and magnetic tape devices.

Another machine from the same era was the National Cash Register model 102-D. It was similar to the Elecom and also used drum memory.

National Cash Register 102-D computer