IBM 7320

The IBM 7320 is a discontinued magnetic drum, count key data storage unit manufactured by IBM. It was announced on December 10, 1962[1] for the IBM 7090 and 7094 computer systems, was retained for the earliest System/360 systems, and was discontinued in 1965. The 7320 is a vertically-mounted head-per-track device with 449 tracks, 400 data tracks, 40 alternate tracks, and 9 clock/format tracks. The rotational speed is 3490 rpm, so the average rotational delay is 8.6 milliseconds.[2]

Attachment to a 709x system is through an IBM 7631 File Control unit, which can attach up to five random-access storage units, a mix of 7320 and 1301 DASD. One or two 7631 controllers can attach to a computer system, but the system can still attach only a total of five DASD. When used with a 709x, a track holds 2796 six-bit characters, and a 7320 unit holds 1,118,400 characters. Data transfer rate is 202,800 characters per second.[2]

The 7320 attaches to a System/360 through a 2841 Storage Control unit. Each 2841 can attach up to eight 7320 devices. When used with System/360, a track holds 2081 eight-bit bytes, and a 7320 unit holds 878,000 bytes. Data transfer rate is 135,000 bytes per second.[3]

The 7320 was superseded by the IBM 2301 in mid-1966.[4] [5]

References
  1. IBM Corporation. "DPD chronology". IBM Archives. Retrieved Dec 6, 2019.
  2. IBM Corporation (1962). IBM 7320 Drum Storage (PDF). Retrieved Dec 6, 2019.
  3. IBM Corporation. IBM System/360 Component descriptions-2841 Storage Control Unit 2302 Disk Storage Models 3 and 4 2311 Disk Storage Drive 2321 Data Cell Drive Model 1 7320 Drum Storage (PDF). p. 41. Retrieved Dec 6, 2019.
  4. Pugh, Emerson W.; Johnson, Lyle R.; Palmer, John H. (1991). IBM's 360 and Early 370 Systems. MIT Press. p. 272. ISBN 0-262-16123-0.
  5. Office of Naval Research (1961). "Digital Computer Newsletter". 13 (1, 2): 7–8. Retrieved Dec 6, 2019. Cite journal requires |journal= (help)
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