Ancestors

Written by Ken Shirriff on 2025-02-01 at 18:56

What is the origin of the word "mainframe"? Digging through archives, I traced it back to 1953. The IBM 701 computer was built from "frames": power frames, a storage frame, a drum frame, and the main frame. This 1953 drawing from the Installation Manual shows the dimensions of the "main frame". 1/n

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Written by Ken Shirriff on 2025-02-01 at 18:56

IBM's construction of computers from frames was a major innovation: the frames fit through doors and were transportable. Earlier computers were often constructed in place and difficult to move. Photo shows an IBM 701 at GE with frames for power and drum storage, and main frame in the center.

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Written by Ken Shirriff on 2025-02-01 at 18:58

IBM's engineering documentation extensively used the term "main frame". The documentation described the location of each tube in the system. The abbreviation "MF" indicated the tube was in the main frame, as in the schematic diagram. 3/n

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Written by Ken Shirriff on 2025-02-01 at 18:59

From the 1950s to the 1980s, the word "mainframe" indicated the physical box or cabinet that held the computer. Even a personal computer had a "mainframe". 4/n

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Written by Ken Shirriff on 2025-02-01 at 18:59

At the same time, "mainframe" took on a different but related meaning: a computer's CPU (central processing unit). By the 1980s, however, this definition faded away: a book stated: "According to the official definition, 'mainframe' and 'CPU' are synonyms. Nobody uses the word mainframe that way."

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Written by Ken Shirriff on 2025-02-01 at 19:00

With the development of the minicomputer and the microcomputer in the 1970s, "mainframe" moved towards its modern meaning, with computers partitioned into micros, minis, and mainframes. IBM started using "mainframe" as a marketing term in the mid-1980s; e.g. calling the S/390 "mainframe class". 6/n

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Written by Ken Shirriff on 2025-02-01 at 19:00

Analyzing newspapers shows the rise and fall of the term "mainframe". The term became popular during the 1980s. At the end of the 1990s, as the popularity of mainframe computers dropped, usage of the term steeply dropped too. 7/n

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Written by Ken Shirriff on 2025-02-01 at 19:01

For more on the history of the word "mainframe", see my latest article: https://www.righto.com/2025/02/origin-of-mainframe-term.html

Thanks to the Computer History Museum for letting me examine their archives.

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Toot

Written by Vertigo #$FF on 2025-02-01 at 19:46

@kenshirriff Tagging #mainframe (see up-thread)

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Descendants