【Electrotechnical Laboratory】 High-speed Magnetic Drum for ETL Mark IV

The Electrotechnical Laboratory planned the development of a magnetic drum unit for the internal memory of the ETL Mark IV transistor computer by studying a high-speed magnetic drum unit from the Ferranti Corporation (Canada). In 1956, the mechanical part was contracted to Hokushin Electric (which later became Yokogawa Hokushin Electric, and today is known as Yokogawa Electric), a company with experience manufacturing gyrocompasses, and the magnetic part was contracted to Tokyo Tsushin Kogyo (later known as Sony), a firm with experience in the area of tape recorders. In 1957, a high-speed magnetic drum was completed, with a rotation speed of 18,000rpm, an average access time of 1.65ms and a memory capacity of 1,000 words.

High-speed Magnetic Drum for ETL Mark IV