Remarkable mass storage devices


IBM 2321 Data Cell

cell cell_top
Top left: components of the data cell drive (reproduced from Pugh, Johnson and Palmer: "IBM's 360 and early 370 systems", MIT Press 1991). The rightmost picture shows a single data cell's top with protruding strips. Below: the cell in its storage container. The measuring tape is divided in centimeters.
cell_doos
The IBM 2321 Data Cell Drive was introduced in 1964, after years of development work, as a very large capacity storage system. The total storage capacity was about 400 Mb.
The drive accomodated 10 removable and interchangeable data cells like the one shown above. Each data cell contained 200 2.25" by 13" magnetic strips. After selection a strip was taken from the cell and wrapped around a drum. Average access times: selection of a strip from a cell 400 ms; rotational delay once a strip is on the drum 25 ms; selecting a track 95 milliseconds. Reportedly the device worked not very reliably.

IBM 3850 Mass Storage System

This tape cartridge, 1.65" in diameter, 3.5" long and containing 770 inches of 2.75" wide magnetic tape, held about about 50 Mbytes. Cartridges of this type were used in the IBM 3850 Mass Storage System, a tape robot avant la lettre accomodating up to almost 10000 cartridges sitting in hexagonal pigeon holes.
Like modern video tape, the 3850 tapes were read and written by helical scanning. The 3850 was designed to store images of the Model 3330 Disk File. Two cartridges would contain the image of a 3336 disk pack. The 3850 MSS was introduced in 1974.

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