IBM 3370 direct access storage device


IBM 3370 Direct Access Storage Device
  • Models A1, B1, A11, and B11 announced January 30, 1979 and withdrawn August 5, 1986
  • Models A2, B2, A12 and B12 announced September 15, 1983
The IBM 3370 of 1979 introduced thin-film head technology to large disk files. Work on thin-film head structures was started in IBM's Thomas J. Watson Research Center in Yorktown Heights, N.Y., in the late-1960s.
The 3370 direct access storage device (DASD) was an advanced fixed-media disk unit that initially provided 571.3 megabytes of auxiliary storage for IBM's 4331 and 4341 processors and the IBM System/38 midrange computer. Up to four 3370 devices could be attached to any System/38 Model 5 for an additional 2,285.5 megabytes of auxiliary storage.
Average seek time was 20 milliseconds and the nominal data rate was 1.859 megabytes per second.
Two 3370s were available in February 1980 for attachment to System/38: Model A11 attached to the IBM 5381 System Unit Model 5, and up to three Model B11s could be connected through an A11 unit.
At announcement, a Model A11 could be leased for $900 a month, rented for $1,058 a month or purchased for $35,100. Corresponding charges for each B11 unit were $600, $705 and $23,400.

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