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(Random Access Method of Accounting and Control) The first hard disk computer, introduced by IBM in 1956. All 50 of its 24" platters together held a total of five million 8-bit alphanumeric characters (5MB). Weighing more than a ton, RAMAC was half computer, half tabulator, and more than a thousand units were built until production ceased in 1961. The RAMAC had a drum memory for program storage, but its I/O was wired by plugboard. The machine was a major breakthrough as all prior computer storage used magnetic tape.

RAMAC leased for USD $38,400 per year, equivalent to roughly $300,000 in 2016 dollars. About a third of the cost was RAMAC's "huge" disk system. However, 60 years later, that same amount of storage cost less than one thousandth of one cent on a multi-terabyte hard drive. See tabulator.

The RAMAC, 1956
At 2,000 magnetic bits per square inch, IBM's RAMAC was an amazing technology in the 1950s. Each 24" platter held a whopping 100,000 characters (no bytes then) for a total of five million characters. (Images courtesy of IBM.)

RAMAC Resurrected
In 1994, IBM reinstated the RAMAC name for its hard disk arrays. In 38 years, areal density vaulted from 2,000 to 259,500,000 bits per square inch, and access time decreased from 600 milliseconds to 9.5. (Image courtesy of IBM.)


A machine that added up numerical data in punch cards. Tabulators were used to prepare invoices, checks and "green-striped" reports as late as the 1970s. Invented by Herman Hollerith in 1890, his tabulator displayed the totals on dials. Subsequent models were able to perform additional arithmetic operations as well as print the results. See Hollerith machine, punch card and continuous forms.

First Tabulator - 1890 U.S. Census
After placing the punch card in the reader and pulling the handle down, the dials incremented, and the card was dropped into the sorting box that opened. (Image courtesy of The Computer History Museum,

A Tabulator in the 1960s
Tabulating machines such as the IBM 407 (left) were used to print millions of reports, invoices and checks. Hollerith's company evolved into IBM, and IBM was always the leading tabulating equipment vendor (see Hollerith machine). (Image courtesy of IBM.)

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