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Old Computers

  1. Oct 23, 2005 #1
    I'm trying to find a picture of a pre-transistor computer that I can compare to my iPod. Any help would be appreciated.
     
  2. jcsd
  3. Oct 23, 2005 #2
    I found this:
    (emphasis added)

    What is meant by 300 calculations/s?
     
  4. Oct 23, 2005 #3

    dduardo

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  5. Oct 23, 2005 #4
  6. Oct 23, 2005 #5

    dduardo

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    The ipod uses two ARM 7TDMI processors. Each is capable of 130MIPS => 130 million instructions per second.

    http://en.wikipedia.org/wiki/ARM7TDMI
     
    Last edited: Oct 23, 2005
  7. Oct 23, 2005 #6
    Thanks a lot!
     
  8. Oct 23, 2005 #7

    Ouabache

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    Too bad the images only show the front end.. The business end (tube circuitry) would be of interest to me. I hear that is where they had to debug. Yes physically clean bugs out from between the tube circuits.
     
  9. Oct 23, 2005 #8

    Pengwuino

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    That's where the term "computer bug" came from!
     
  10. Oct 23, 2005 #9

    Ouabache

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    You're catchin' on.. :wink:
     
  11. Oct 23, 2005 #10

    James R

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    Here's one of the very early computers built in Australia in 1947, called "CSIRAC". It was the 5th stored-program electronic computer ever built.

    http://www.cs.mu.oz.au/csirac/

    Click on the link to "Vital statistics" to compare the old and the new.
     
  12. Oct 24, 2005 #11

    russ_watters

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    It is also worth pointing out that those are either 16 or 32bit instructions. Eniac was probably 8bit (not sure, but it can't be less, can it?).
     
  13. Nov 1, 2005 #12

    -Job-

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    It would be hard to have it less than 8 bits, seeing as the next power of two is 4, how would that work? The first bit for the instruction and three bits for the data/memory location? :smile: A whopping two different instructions!! Of course it's actually feasible, since the logical AND and NOT are all you need to do anything really, but you need more bits for the data/memory-location. The number of bits doesn't have to be a power of 2 either but it's more optimizable. I wonder if they were using bits and bytes by then though or if that came later.
     
  14. Nov 1, 2005 #13

    robphy

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  15. Nov 1, 2005 #14

    jtbell

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  16. Nov 1, 2005 #15

    Integral

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    I am not sure how common this was, Grace Hopper tells of finding a moth caught in a relay, which caused a failure and hence the term "bug" was born. I'll bet it more of a unique event that a common occurrence.
     
  17. Nov 1, 2005 #16

    Ouabache

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    I first heard it mentioned in one of my computer design classes. I recall the prof handing out copies showing the working end (circuit side) of an ENIAC or similar machine . He told us that bugs had to be periodically cleaned from the tubes, coining the expression, debugging the system.

    Here is an online description:
    "Because the tubes actually glowed and gave off heat, they attracted moths and other bugs, which caused short circuits. Scientists would have to periodically "debug," which literally meant shutting down the computer and cleaning out the dead bugs (which is why still to this day, fixing computer problems is called debugging)." ref
     
  18. Nov 2, 2005 #17

    Integral

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    As the name implies, vacuum tubes are sealed, I am not sure how, even if the computer were running in the middle of a field, that a moth would cause the failure of a vacuum tube. I would consider that story a urban legend until proven otherwise. I leaned electronics in the vacuum tube days, so I am quite familiar with them. The filament glow of a vacuum tube is simply not bright enough to draw moths or any other bug. The computers of this era had to be ran in well cooled rooms, this generally implies some level of environmental control ie, limited access to bugs. While I tend to believe Grace Hoppers story (I heard her tell on a TV show a few years back) which involved a single bug (not stated what kind) caught in the contacts of a mechanical relay. I am skeptical of stories of many bugs immolating them selfs from the heat of a vacuum tube.

    Here is Grace Hoppers verision, including a picture of the moth taped to the lab book.
     
    Last edited: Nov 2, 2005
  19. Nov 2, 2005 #18

    Ouabache

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    The mechanism of failure for a tube circuit is analogous to a modern circuit. Since you are familiar with tube circuits, let me describe for our PF readership, tubes are plugged into sockets. Those sockets are wired to the rest of the circuit (i.e. to other tubes and various components resistors, capacitors, etc...) When bugs get too close to a hot tube, or between high voltage connections, they will fry and accumulate. As bugs are composed of organic compounds and charged salts, they can cause a short between two points that are not supposed to be connected, potentially causing errors to develop in the program.
    Here I differ with your thoughts. I’m also familiar with vacuum tube circuits and observed them glowing plenty bright, to attract insects. And the infrared radiation (heat) of a vacuum tube will also attract bugs. (For those curious about vacuum tube circuits, you can find good working broadcast tube-radios and older amateur radio transmitters and recievers, that work as well today as they did in their heyday. Enthusiasts affectionately refer to the tubes as bottles that glow in the dark).
    Yes jtbell also posted the same reference on this thread. In my last post you will see, I quoted a reference, from the physics department at UCLA. I give them more credibility than describing their information as urban legend.:smile:
     
    Last edited: Nov 2, 2005
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