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Thread: Tube computer size: ENIAC vs Bendix G15

  1. #11
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    The first miniature tubes that I encountered were as a young tech in the Navy, late 50' and early 60's. The AN/ARN-21 TACAN (Tactical Air Navigation), manufactured by the Collins Radio Corporation, had state of the art interchangable "books" which could be easily removed and replaced in the chassis. These books consisted of various miniature tubes and you needed to demonstrate a good soldering technique. The ARN-21, with its mini-tubes, remained in military use even after being upgraded to the ARN-158 solid state version during the early 70's. As a note, those tubes were durable and highly reliable as they withstood countless carrier launches and landings.

  2. #12

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    Alright, this makes a lot of sense. I suppose with ENIAC, they built and tested it in pieces. It still seems crazy to build such a huge machine as your 'first computer.' But, now that I think if it, it's probably easier to lay the whole thing out with large, bulky, parallel logic, than it is to figure out how to serialize the operations down to something small like the Bendix. I read some more about how it works, with the long and short serial tracks on a spinning drum. Very fascinating.
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  3. #13
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    The earlier ABC was much smaller than ENIAC.

  4. #14

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    Now that was more like what I would expect for a first electronic computer. It's not stored program, but neither was ENIAC when it was first used.
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  5. #15
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    It's always struck me that Antanasoff would likely have added a third drum whose function was to push the right buttons if he'd had the time and resources.

  6. #16

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    Quote Originally Posted by carangil View Post
    Now that was more like what I would expect for a first electronic computer. It's not stored program, but neither was ENIAC when it was first used.
    But the whole point of the ENIAC was to not be what those earlier machines were. It was fully electronic, not partly mechanical.
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  7. #17
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    On Antanasoff's machine, pretty much only the I/O was mechanical. Yes, it used rotating capacitive drums for storage, but that's not a big thing--computers still use rotating magnetic disks.

    On most computers of the last 70 years, I/O is still mechanical, be it a punch, reader, tape drive, disk drive, printer, keyboard, or whatnot. ENIAC was no different. The ABC had an all-electronic core, unlike, say, Konrad Zuse's Z3 of about the same time period, which used relays for computation.

  8. #18

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    As to the G-15 being small relative to ENIAC, ENIAC was in essence a research machine. Whirlwind, the worlds first "real-time" computer intended to be part of a feedback control loop was as well, designed as more or less a large breadboard layout so as they discovered problems it would be easy to modify. Although I never saw Whirlwind in operation, I did as a new college student in the mid 1960's spend a little time writing ALGO on a G-15 (attached a photo to prove it :-) I also have both a G-15 flip-flop module and a Whirlwind module (register driver type 1 serial number 3) in my collection (I hang the G-15 module from my Christmas tree each year as an ornament along with several PDP-8 R202's and DDP-516 modules :-). I recall reading in one of the trade magazines (maybe Datamation or EDN) in the mid 70's celebrating the 20th anniversary of the G-15 and mentioning that it was the worlds first personal computer :-) Behind the IBM 650, the G-15 and the LGP-30 shared second place as the most produced vacuum tube computers, all drum machines.
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