Model 801 Magnetic Disk Unit

After developing the Model 101 magnetic disk pack unit, the Electrical Communication Laboratories (ECL) of Nippon Telegraph and Telephone Public Corporation (now NTT) set a goal of achieving a linear recording density of 1,000 bit/mm (6 times the practical recording density at the time). They began full-scale research development in 1974 on issues such as magnetic disks incorporating thin-film, electromagnetic conversion in magnetic heads, recording/playback circuits, head floating mechanisms, positioner mechanisms, and packaging.