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September 13, 2013 AT 11:26 am

IBM intros 1st computer disk storage unit, September 13, 1956


IBM intros 1st computer disk storage unit, September 13, 1956

Weighing in at more than a ton and storing 5MB of data, the IBM 305 RAMAC was the first super computer with a hard disk drive (HDD).

Introduced by IBM on September 13, 1956, RAMAC stood for “Random Access Method of Accounting and Control” and used a moving head hard disk drive (magnetic disk storage) for secondary storage.

So large that it had to be moved by forklift and transported by plane, the original 305 RAMAC computer system could be housed in a room of about 9 meters by 15 meters. The 350 disk storage unit, itself, measured around 1.5 square meters.

The machine stored 5 million 8-bit (7 data bits plus 1 parity bit) characters, the equivalent of 64,000 punch cards, on 50 24-inch magnetic disks.


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