RAMAC
(Random Access Method of Accounting and Control) The first hard disk computer, introduced by IBM in 1956. All 50 of its 24" platters held a total of five million characters! RAMAC was half computer, half tabulator. It had a drum memory for program storage, but its I/O was wired by plugboard. The machine was a major breakthrough as all computer storage prior to the RAMAC used magnetic tape. See tabulator.
A World of Difference in Four Decades!
In 1994, nearly four decades later, IBM resurrected the RAMAC name as new brand of high-capacity disk storage systems. The differences between the 1956 and 1994 RAMACs were rather dramatic. Areal density rose from 2,000 bits per square inch to 260,000,000 bits per square inch, increasing total storage capacity from five million bytes to 90 billion bytes. Access times were reduced from more than a half second to less than a hundredth of a second (600 ms to 9.5 ms).
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| The RAMAC, 1956 |
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| Part computer, part tabulator, IBM's RAMAC was the first machine with a hard disk, an extraordinary technology of the times. Each of the 24" diameter platters held a whopping 100,000 characters (they weren't called bytes then) for a total of five million characters. (Images courtesy of International Business Machines Corporation. Unauthorized use not permitted.) |
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| RAMAC Resurrected |
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| In 1994, IBM reinstated the RAMAC name for its new hard disk arrays. In the ensuing 38 years, areal density grew from 2,000 to 259,500,000 bits per square inch and access time decreased from 600 milliseconds to 9.5. The first RAMAC held 5MB compared to this one which holds 90,000MB (90GB). Subsequent storage arrays from IBM hold terabytes in this much space. (Image courtesy of International Business Machines Corporation. Unauthorized use not permitted.) |