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Thread: Mainframe definition

  1. #1

    Default Mainframe definition

    My (tongue-in-cheek) concept of a "mainframe" is any computer system which weighed so much that it required a truck/tractor/forklift to move it into the computer room! In several pieces.

    For example, an IBM S34 is NOT a mainframe, nor is a UNIVAC 1004. However a UNIVAC I or an IBM 705 II most assuredly are. The aforementioned systems are history and most current desktops can easily out perform them all, (In fact, I suppose my iPaq could!) but they were the mainframes which started the computer field. Put the US on the moon.

    The old UNIVAC I, II and III were gigantic! Some, you could actually walk into. The IBM 705s the 7080, both were huge. The IBM 705 vacuum tube filaments alone probably consumed more power per day than my household per month! I sometimes dream (too much pasta and vino?) I'm troubleshooting one of these old systems again, with a trusty Tektronic 310 or a 545. Staring into a small green CRT, trying to find the sneak pulse or the non-kosher level. These tube computers could shock the crap out of you! (B+ could mean Brown and Served!) Maybe the dream was a nightmare?

  2. #2
    Join Date
    Apr 2003
    Saginaw, MI, USA 48601
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    I often refer to smaller (desktop) systems as mainframes, i.e. 'S-100 mainframe', but a quick google reveals that the term is usually reserved for large and/or multi-user systems by the computer community as a whole.

    Teach your children how to think, not what, and hold 'em close, not tight.

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  3. #3

    Default Mainframe, continued

    To be serious, the term mainframe is somewhat dated. When I left the "mainframe" arena, (the nineties)the IBM 30xx systems were the big mainframes with the Enterprise 390 just appearing. I haven't a clue how many such systems remain.

    I was fortunate enough to work on every kind of calculating device from mechanical calculators, thru tubes, descrete solid state computers and on into modern VLSI systems. Fortysome years in field service.

    IBM had a series of Mini-s called the System 36 There was a 5361, 5362, a 5363 and a 5364 The 5364 was termed the baby 36 and had a much modified AT desktop as part of the two box system. Even though it ran a stupid RPG, It was far more capable than the huge room filling mainframes of yesteryear. It used ESDI hard drives. Various printers, and a late appearing 8 inch Floppy drive.

  4. #4


    Yep, in 1968 I would use a Bendix G15 to warm up the room. The tubes were on huge hinges and you could swing them out. Reminded me of a large bathroom radiant heater. That "rotating drum RAM(?)" was very cute also.

  5. #5


    Quote Originally Posted by Woodym1 View Post
    My (tongue-in-cheek) concept of a "mainframe" is any computer system which weighed so much that it required a truck/tractor/forklift to move it into the computer room! In several pieces.

    For example, an IBM S34 is NOT a mainframe...
    Actually IBM's definition of the difference between a mainframe and "minicomputer" (which were mostly the System/34, 36, 38, AS400 level) was the *price*. If anyone wants to see a few S/34s & a couple of their printers being moved I have a group of photos from a few years back: . Still have them sitting around where the picture set ends.

  6. #6


    For the record...I consider an IBM Series 1 system to be a minicomputer system, even though each component is so heavy that I'd need a car jack to position them onto the rack shelves. These were IBM systems built in the late 70's early 80's.

  7. #7

    Default Series 1

    I had not thought of the Series 1 in years! It was out of IBM's GSD. Even the USMC had a small ruggedized OD one. I always figured that under hostile fire, I might save my butt prior to worrying about my computer! Talk about a "luggable"... Two or more heavy pieces. (Wait sergeant! We can't advance our position yet, I just started payroll!)

    I recall they ran AIX, or some flavor of UNIX, or IBM's EDX. It did have a large selection of I/O options.

    Series 1; still a mini, although big blue may have categorized it otherwise.

  8. #8


    I made a living (well, sort of) working on a Series/1 from 1984 to 1992. First one was in Las Vegas where I did accounting type programs in EDL (Event Driven Language) for the Hilton hotel chain. Then a few years at Baxter International in Glendale CA where they used it for production control and plasma accounting (blood plasma, that yellow liquid when you break open a burn). Baxter would pay donors (if you pay them, are they still a donor?) and make very expensive biological products out of the plasma. The Series/1 computers were still going strong in 1992 when Baxter sold the Plasma business to someone else. Out which point, I became a Novell Certified Network Engineer doing network crud.

  9. #9

    Default Mini/mainframe continued

    Hey, I also was a Novell CNE! I am particularly proud of ace-ing the "Service and Support" exam. In the mid-90s.
    I never took any of the the 4.X exams, I was too busy making a living after accepting "early retirement" from the big stuff. Minis and PCs were fun. I even slipped into some weird stuff such as ATMs, Banking, Industrial, Gas Analysis.

    Thank God I'm retired!

  10. #10


    Hmmm...I used to figure that if you were supporting hundreds of users, it was a midrange (mini) system, but if you had a thousand or more users, it would be a mainframe. Of course that mentality follows the world of "dumb" terminals from the earliest days. I'm not sure that even applies to modern systems. As an example, our AS/400 will support about 600 users. That is, about 600 directly connected Twinax devices--terminals & printers. On the other hand, thousands of people can connect to it over a conventional network in a client-server environment. So is it a Mainframe? Gut tells me no...

    Yet, a system/390 (IBM) might be considered a Mainframe. Is it jus raw processing power? Or size? Even the 390 isn't a very big machine compared to a Univac I...

    In the AS/400 (now I-Series) machines, a lot of tedious processing is pushed off to intelligen peripheral devices such as work station controllers and communication controllers. Does this architecture perhaps lead to the differentiation?
    Windows: worst operating system in the world, almost two decades running!


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