******************************EXCERPT*************************
IBM 3850 Mass Storage System
- IBM 3850 Mass Storage System announced October 9, 1974
- IBM 3851 Mass Storage Facility Models A1-A4 and B1-B4 announced October 9, 1974 and withdrawn August 5, 1986
- IBM 3851 Mass Storage Facility Models B11-B13, B21, B22 and B31 announced March 6, 1980 and withdrawn August 5, 1986
Beginning in the late-1960s, IBM engineers in Boulder, Colorado, began development of a low-cost mass storage system based on magnetic tape in cartridges. By 1970, the proposed device was code named "Comanche" and described as an online tape library to provide computer-controlled access to stored information. Numerous marketing studies and design changes were made during the early 1970s, and finally Comanche was announced as the IBM 3850 Mass Storage System (MSS) in October 1974.
The components of the 3850 were new data cartridges, one or two units of the IBM 3851 Mass Storage Facility, the new IBM 3830 Storage Control Model 3, and the widely-used 3330-series disk subsystem.
The data cartridges were circular cylinders, two inches in diameter and four inches long, each holding a spool holding 770 inches of tape. Cartridges were stored in a two-dimensional array of bins, which were hexagonal, rather than square, to save space.
The 3850's honeycomb storage compartments
During its development, Comanche evolved in concept and design from a tape library to a means for storing infrequently-used information that otherwise would reside on disk storage. Information under control of the MSS was stored in Direct Access Storage Device (DASD) format images on the low-cost cartridge tape.