Punched card system

Discussion in 'General Electronics Chat' started by Robin Mitchell, Nov 19, 2009.

  1. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
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    Hi guys!!!

    Ok, before you go charging at me at full speed you must know something, I LOVE THE PAST. Because of this I want magenetic memory and punched paper.

    So, what would be the best way to make a device that can read the punched card. Metal contacts? LDR's?
    If you want to know, the card (paper really) would be a long strip that is "threaded" through

    Thanks
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,766
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    Optical, light beams and photo transistors (or LDR, AKA photocell, AKA electric eye). The next step (and I've used these devices in the 80's (built in the early 70's) is paper tape.
     
  3. russ_hensel

    Well-Known Member

    Jan 11, 2009
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    I would go optical, a photo transistor would be the first device I would look at. Use say an Arduino ( or any similar uC ) to interpert the data.
     
  4. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
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    That sounds good but im worried that the LDR's may pick up other light sources like the light entering a diffrent hole. How could i prevent this?
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    The past may seem romantic to you, but wait until you have spent a few hours adjusting drive currents through core memory, or rebuilding a paper tape bunch before waxing overly rhapsodic.

    If you want the reader to be a real blast from the past, use phototubes (925's) instead of phototransistors.
     
  6. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
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    What do you mean :

    "but wait until you have spent a few hours adjusting drive currents through core memory, or rebuilding a paper tape bunch before waxing overly rhapsodic.
    "

    Oh, WHAT IS IT WITH TUBES? why are they special? is it because of the vacuum?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Fun project. ;) It may be a tad frustrating, though.

    Here's an idea for a data tape format:

    [​IMG]

    The left column are holes representing a clock. The holes are smaller than other holes in the tape; this helps to ensure that the other bits will be unambiguous.

    Every time a clock is detected, the data on the tape should be latched into a memory location, and the memory location counter advanced.

    Columns 7 through 0 are bits 7 through 0 of an 8-bit byte.
    The rightmost column is parity. This will help to guard against a single missing bit, but won't help if even multiples of bits are missing. You could use even or odd parity.

    It would be better to have the clock holes in the center of the tape; this will help to ensure alignment of the data/parity bits.
     
    Last edited: Nov 19, 2009
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    Here's a few links to illustrate a bit of the past.

    Core memory - http://www.yesterdaystechnology.com/html/core_memory.html

    Paper tape - http://www.yesterdaystechnology.com/html/paper_tape.html

    A Hollerith punch card - http://www.yesterdaystechnology.com/html/punched_cards.html

    If you want very old technology - http://ed-thelen.org/comp-hist/SEAC-Williams-tube-desc.html

    Or delay line memory - http://ed-thelen.org/comp-hist/vs-univac-mercury-memory.html

    Don't forget the magnetic tape deck and printers - http://www.dvq.com/ads/potter_dm_2_63.jpg

    Look a bit further and found the stuff I worked on - http://www.dvq.com/ads/univac_1206_dm_11_61.jpg
     
    Last edited: Nov 19, 2009
  9. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
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    :( I love you guys sooo much, especially Beenthere. I have searched and searched for this kind of infomation, thanks sooooo much :)

    Oh, Sgt. Here are two paper memory cards I designed. Im going for the one with 4 bits in a row because its easier to punch and read than the single line.
     
  10. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
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    Standard punch tape equipment is still often available at computer junk sales and on ebay.

    Search for 'paper tape reader'

    Also keep an eye out for a Teletype model ASR-33
    This is a combined Keyboard - Printer - Paper tape Punch & Reader.
    Example:
    http://www.vintage-computer.com/asr33.shtml

    These were one of the commonest I/O devices on minicomputers and also used for dial-up access to mainframes.

    Another old input system that may be practical is 'Mark Sense Cards'

    These have faint outline frames in a grid, plus black index marks along one edge to show the centre or dividel line line of each grid row.
    You just fill in the appropriate outline marks with pencil and feed them through an optical reader.
    Some examples:
    http://www.cs.uiowa.edu/~jones/cards/collection/i-optical.html

    Some electronics companies used a form of these many years ago to allow customers to submit programs to be burnt into one-shot PROM chips.
     
  11. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
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    Provide your own illumination, perhaps inside a box, do not let the photo transistor see any ambient light with or without a hole or a tape.
     
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