How The Main Frame Became The Mainframe: An Etymological Dissertation

In his most recent article, [Ken Shirriff] takes a break from putting ASICs under a microscope, and instead does the same in a proverbial manner with the word ‘mainframe’. Although these days the word ‘mainframe’ brings to mind a lumbering behemoth of a system that probably handles things like finances and other business things, but originally the ‘main frame’ was just one of many ‘frames’. Which brings us to the early computer systems.

We have all seen the photos of early computer systems, which not only filled rooms, but which also tended to consist of multiple units. This was something which the designers of the IBM 701 computer seem to have come up with, to make it possible to transport and install computer systems without cranes and the breaking out of walls. Within the IBM 701 system’s internal documentation, the unit containing the core logic was referred to as the ‘main frame’, alongside the ‘power frame’, the ‘core frame’, etc.

From this [Ken] then traces how the word ‘main frame’ got reused over the years, eventually making it outside of the IBM world, with a 1978 Radio Electronics magazine defining the ‘mainframe’ as the enclosure for the computer, separating it seemingly from peripherals. This definition seems to have stuck, with BYTE and other magazines using this definition.

By the 1960s the two words ‘main frame’ had already seen itself hyphenated and smushed together into a singular word  before the 1980s redefined it as ‘a large computer’. Naturally marketing at IBM and elsewhere leaned into the word ‘mainframe’ as a token of power and reliability, as well as a way to distinguish it from the dinky little computers that people had at home or on their office desk.

Truly, after three-quarters of a century, the word ‘mainframe’ has become a reflection of computing history itself.

12 thoughts on “How The Main Frame Became The Mainframe: An Etymological Dissertation

  1. I’m going to engage in some wild speculation here from this side of the pond; Colossus was built by Tommy Flowers, a GPO / British Telecom engineer, using most parts from the extant telephone exchange equipment parts bin.

    Every telephone exchange has frames – typically at the very least the Main Distribution Frame – for physically cross-connecting all the incoming lines to available slots on the equipment. I’m wondering if frames entered the computing nomenclature from early cross-pollination with the telecomms engineers who would be very familiar with almost everything in early computers.

    Usagi Electric’s restoration of the Bendix shows just how much similarity there is – racks of wire-wrapped connections to slot-in modules or cards, relays and tubes – all this stuff could have been picked straight out of the catalogue of standard exchange components back then. Presumably that could extend to equipment racks / frames and other ancillaries.

    1. I think this topic came up on Ken Shirriff’s footnotes too. Footnote#1 – The phrase “main frame” in non-computer contexts has a very old but irrelevant history, describing many things that have a frame. For example, it appears in thousands of patents from the 1800s, including drills, saws, a meat cutter, a cider mill, printing presses, and corn planters. This shows that it was natural to use the phrase “main frame” when describing something constructed from frames. Telephony uses a Main distribution frame or “main frame” for wiring, going back to 1902. Some people claim that the computer use of “mainframe” is related to the telephony use, but I don’t think they are related. In particular, a telephone main distribution frame looks nothing like a computer mainframe. Moreover, the computer use and the telephony use developed separately; if the computer use started in, say, Bell Labs, a connection would be more plausible.

      1. A telephone cabling MDF is not like an equipment frame or rack but I would almost guarantee there’s a large overlap between folks who working on exchange switching & transmission equipment and folks working on early computers and other such machines as telephony equipment was by far the main consumer of such electronics up until it got overtaken by computing some decades later.

  2. Say “Mainframe” like in “your new IBM OS system should run better with that IBM system memory extension beside your mainframe”, as the IBM commercial engineer did…

    Then came the Memorex commercial engineer…

  3. Economies of scale. At the time it was cheaper to have centralized processing with distributed terminals. Compuserve made bank on it. Then the mainframes got smaller with “mini’s” and saw more widespread adoption. Then PC’s happened and it was over… for a time. We still have “mainframes”, but we call them “server farms” for “cloud computing”. Back to centralized information storage and processing with distribution to users.

    1. Oh, we still have actual mainframes that are not just server farms. They’re used for LOTS of core functions of our banking and government systems. IBM continues to sell Z series machines for a lot of money. Of course, they’ve got some new tricks up their sleeves (they’ve been doing virtualization for a lot longer than anyone else), but it’s clear lineage. Back in the early 2000’s I did an analysis of running Weblogic Server on the Z9000 for a big financial firm. They ended up going with Websphere…

  4. We had an interesting discussion over @ one of the stack exchange sites recently (probably retrocomputing) about the etymology and origin of the term “card” as it applies to computer components. It was all speculative and we didn’t really dig up anything concrete, which was sort of an interesting result in its own right. (Tho admittedly it may have been more for lack of effort, than lack of available information.)

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