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 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.
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.
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.
The 7320 was superseded by the IBM 2301 in mid-1966.
