1973: "Winchester" pioneers key HDD technology

IBM 3340 employs new low-cost, low-load, landing read/write heads

In 1969, IBM charged San Jose project manager Kenneth E. Haughton with developing a “direct access storage facility” that matched the performance of the high-end IBM 3330 system at a price attractive to low-end System/370 computer customers. The IBM3340 hard disk drive (HDD) that began shipping in November 1973 pioneered new low-cost, low-load, landing read/write heads with lubricated disks, and established what became the dominant HDD technology. Al Shugart identified this new “Winchester head” as one of the four most significant developments in mass storage.

Derived from the original specification of a system having two spindles each with a disk capacity of 30 MB, Haughton is reported to have said: "If it's a 30-30, then it must be a Winchester" after the .30-30 Winchester rifle cartridge. With a load of less than 20 grams, the ferrite read/write head patented by team member Mike Warner started and stopped in contact with the disk on a dedicated landing zone but flew over the disk on an air bearing 18 microinches thick between the magnetic head and spinning disk. The disks, spindle and bearings, head-positioning carriage and head-arm assemblies were all incorporated into a removable sealed cartridge called the IBM 3348 Data Module, invented by Richard B. Mulvany and Rudolf W. Lissner, with capacities of 35 and 70 MB. A track density of 300 tracks per inch and an access time of 25 milliseconds were achieved. The IBM Model 3350 (1975) turned the data module into a non-removable head disk assembly of 317 MB capacity that some observers have called “the real Winchester” and that has remained the fundamental HDD packaging concept to the present day.

  • Warner, M. “Flying magnetic transducer assembly having three rails” U.S. Patent 3,823,416 (Filed: Mar. 1, 1973 Issued: Jul 9 1974)
  • Frush, Donald Irwin. “Apparatus and method for avoiding defects in the recording medium within a peripheral storage system” U.S. Patent 3,997,876 (Filed: May 6, 1975, 1973 Issued: Dec 14, 1976)
  • “The IBM 3340 . . . ahead of the pack” IBM Marketing Brochure (May 1973)
  • Mulvany, R. B. “Engineering Design of a Disk Storage Facility with Data Modules” IBM Journal of Research and Development (Vol. 18 1974)

Rev: 11.15.15