IBM 2841

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The IBM 2841 Storage Control Unit was a Direct Access Storage Device (DASD) control unit introduced with System/360 in 1964.

The 2841 was a microprogrammed control unit "intended for use in controlling access to a disk or strip file or a slow-speed drum storage unit." It attached to a standard System/360 channel,[1] or could also be attached to an IBM 1130 or IBM 1800 Data Acquisition and Control System to add support for 2311 disks.

The 2841 was capable of attaching the following devices:

  • IBM 1302 Disk Storage – up to four modules for a total of 448 mB. A special feature on the 2841 allowed attachment of an additional four modules.
  • IBM 2311 Disk Storage Drive model 1 – up to eight disk drives for a total of 58 mB.
  • IBM 2321 Data Cell – up to eight 2321s for a total of 3.2 gB.
  • IBM 7320 Drum Storage – up to eight units for a total of 6.6 mB.

By December 1969 the IBM 7320 had been replaced by the much faster IBM 2303, which permitted up to two units for a total of 7.8 mB.

Besides the expansion feature for additional 1302s, the 2841 offered two-channel switch, scan, and record overflow special features.[2]

DASD devices introduced after those mentioned did not use the 2841. For example the IBM 2314, the successor to the 2311, featured an integrated controller.[3]

See also[edit]

Further Reading[edit]


  1. ^ Thoburn, F. J. (November 1970). "A Transmission Control Unit for High-speed Computer-to-computer Communication". IBM Journal of Research and Development: 614–619. CiteSeerX: 
  2. ^ IBM Corporation (1964). IBM System/360 System Summary (PDF). p. 27. 
  3. ^ IBM Corporation (1969). IBM System/360 Component Description 2314 Direct Access Storage Facility and 2844 Auxiliary Storage Control (PDF).