FACOM 621 Magnetic Drum Unit

Completed in 1960, the FACOM 621 was a magnetic drum unit used as auxiliary memory for the FACOM 222 large computer from Fujitsu. A magnetic core and magnetic drum unit were used as the main memory unit for the FACOM222P prototype, but the FACOM 621 was newly developed as an auxiliary memory unit for the commercial FACOM 222A, based on the technology of the D101 magnetic drum unit.