IBM 2321 Data Cell
| Company type | Product |
|---|---|
| Industry | Computer storage |
| Founded | April 1964 |
| Defunct | January 1975 |
| Products | Direct access storage device (DASD) |
The IBM 2321 Data Cell was a direct access storage device (DASD) developed for the IBM System/360 and introduced in April 1964. This unit provided a storage capacity of up to 400 megabytes, with access durations varying between 95 and 600 milliseconds, contingent upon the selected strip and data configuration. Data was recorded on short segments of magnetic tape, which led to its informal designation as the "noodle picker" because of the strips' resemblance to pasta. The product was discontinued and removed from the market in January 1975.
Characteristics
The system featured up to ten detachable data cells, each capable of storing 40 megabytes. Every cell contained 200 strips of magnetic tape, measuring wide by long. The aggregate storage capacity amounted to 400 megabytes or 800 million decimal digits. By linking up to eight IBM 2321 units through an IBM 2841 Control Unit, users could achieve more than three gigabytes of total storage space.
When compared to the contemporaneous IBM 2311 Disk Device, the IBM 2321 delivered approximately 55 times greater capacity but operated at roughly one-seventh the speed (85ms versus as much as 600ms access time). A fully configured IBM 2841 hosting eight IBM 2321 drives equated in capacity to 441 IBM 2311 devices, which would otherwise necessitate seven separate data channels and multiple control units.
The mechanism incorporated three simultaneous seeking subsystems: a servo-hydraulic assembly rotated bins to select among subcells; two solenoid-driven components identified the correct strip tab (one of ten per subcell) and determined one of five head positions for the 20-element read/write head, covering 100 tracks per strip. The hydraulic system utilized Mobil DTE Light oil pressurized at 1500 psi; despite initial concerns, oil leaks were infrequent. The device contained an oil reservoir holding .
Although it employed tape as its storage medium, the IBM 2321 is classified as direct access storage because it could retrieve records directly without sequential scanning typical of standard tape drives. Within IBM_System/360 architecture, it was addressed as a DASD using a six-byte seek address (ØBBSCH hex), specifying Bin, Strip, Cylinder, and Head locations.
See also
External links
- The IBM 2321 Data Cell Drive at Columbia University
- The IBM 2321 Data Cell Drive (partial IBM manual)
- Close-up photo of Data Cell drive
- IBM System/360 Component Descriptions - IBM 2841 and Associated DASD (pages 65–72 cover the IBM 2321)
