Model 101 Magnetic Disk Pack Unit

In 1971, the Electrical Communication Laboratories (ECL) of Nippon Telegraph and Telephone Public Corporation (now NTT) began work to develop magnetic disk units for DIPS, and in 1973 they achieved practical application of the Model 101 (JS4360) magnetic disk pack unit with a memory capacity of 100 MB/spindle. For the Model 101, they developed various technologies, including a floating magnetic head with a float gap of approximately 1μm, a head-positioning mechanism with a voice-coil type positioner and control circuit, and a record/playback circuit with a write correction function and AGC function. The unit achieved a linear recording density of 159 bit/mm, track density of 8 tr/mm, average seek time of 30 ms, and data transfer speed of 0.806 MB/s.