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    TSOP the Keyboard scanning glitch.

    • Started by sorenk
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    19-Aug-2007 19:51:27#1 TSOP the Keyboard scanning glitch.

    I've noticed that sometimes a few letters will get turned around despite my confidence that I hit the keys in the correct order.

    Type 'st' really fast. If you type st fast enough, you will get 'ts'. But no matter how fast you type 'ts' you will never get 'st'

    After a bunch of primitive tests (manually hitting two keys in rapid succession), my observation is that at three keyboards on three machines (two laptops (internal and usb), one tower (ps/2) all junked up on Microsoft) consistently render specific keys typed in rapid succession in reverse order.

    For example, the left index home key (Colemak-T) registers before the left middle finger home key (Colemak-S).

    E-R is another combination that gets mixed up. If you type 'er' fast enough you will get 're.'

    My theory is that, this glitch is related to the way keys are scanned (as a matrix) and the frequency of the scan. And that a keyboard that scans more quickly, or better, directly records  the key presses might not have the problem. I haven't tested this glitch on a Macintosh system.

    Please share any information you have with this glitch (experiences, causes, solutions).

    If this your keyboard does not have the glitch, PLEASE post make and motel.

    Last edited by sorenk (19-Aug-2007 19:59:47)

    "Things will get better despite our efforts to improve them" - Will Rogers
    "...even the dog doesn't think I'm a monster." - Humphrey Bogart in The Caine Mutiny (1954)

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    • Shai
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    19-Aug-2007 21:41:05#2 Re: TSOP the Keyboard scanning glitch.

    The short version is that keys are arranged electrically into a set of rows and columns. When you press more than one key at the same time, the keyboard may not be able to uniquely identify each key or the order that they were pressed.

    You can find a more detailed explanation here. And if you want all the gory details, see what happens when you press multiple keys at the same time.

    You can especially notice it when typing keys in the same column, such as "zaq1" (at least on my keyboard).

    I believe that keyboards that support hitting multiple keys at the same time, will also handle better the order in which the keys are pressed. The best keyboards in this aspect will likely be gaming keyboards. See What's a brand of keyboard that allow multiple keys to be pressed?.

    I've also experienced that problem quite often when I achieved high typing speeds. In the end I had to modify my typing technique a bit, so instead of using bursts of fast typing, I just tried to maintain a constant typing rhythm. Maintaining a constant typing rhythm minimizes the chance of that problem occurring, and is probably a good idea anyway because it helps to reduce typing errors.

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    • From: Köln, Germany
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    19-Aug-2007 22:48:39#3 Re: TSOP the Keyboard scanning glitch.

    How can keys be pressed simultaniously consecutive?!

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    10-Sep-2007 02:00:21#4 Re: TSOP the Keyboard scanning glitch.
    vilem said:

    How can keys be pressed simultaniously consecutive?!

    Ok, true simultaneity only exists for light cones. But as Shai elaborated on the matrix. And there is a notable time delay between scans. So if multiple keys are pressed between scans, then the keyboard can not determine which was pressed first.

    "Things will get better despite our efforts to improve them" - Will Rogers
    "...even the dog doesn't think I'm a monster." - Humphrey Bogart in The Caine Mutiny (1954)

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    10-Sep-2007 02:17:24#5 Re: TSOP the Keyboard scanning glitch.
    Shai said:

    I believe that keyboards that support hitting multiple keys at the same time, will also handle better the order in which the keys are pressed. The best keyboards in this aspect will likely be gaming keyboards. See What's a brand of keyboard that allow multiple keys to be pressed?.

    Right now I'm using a Logitech G15, which is a gaming board capable of registering six letter keys pressed together. But it will always render the keys in the same order. I think the trouble is that gaming boards (at lest the one I'm using) use diodes in the matrix to recognize multiple keys pressed between scans. Unfortunatly they don't (at lest my G15 doesn't) seem to increase the scanning rate or read keys directly.

    Shai said:

    I've also experienced that problem quite often when I achieved high typing speeds. In the end I had to modify my typing technique a bit, so instead of using bursts of fast typing, I just tried to maintain a constant typing rhythm. Maintaining a constant typing rhythm minimizes the chance of that problem occurring, and is probably a good idea anyway because it helps to reduce typing errors.

    Your approach is a good work around. But it must sting a bit to know that some those "errors" are the fault of the keyboard manufacturers. And you typed the letters in the proper sequence.

    "Things will get better despite our efforts to improve them" - Will Rogers
    "...even the dog doesn't think I'm a monster." - Humphrey Bogart in The Caine Mutiny (1954)

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    02-Dec-2007 07:34:10#6 Re: TSOP the Keyboard scanning glitch.

    Razer put out two keyboards, the Lycosa and Tarantula that have a scanning rate about 8 times faster than a standard keyboard. It's not quite as good as direct key response, but 8 times faster is scanning makes a huge difference.

    I bought the Tarantula and it's definitely better at getting keys in the correct order (in the order that the keys were pressed). But it's still possible to hit a pair of keys quickly enough to get them out of order.

    Another advantage is that the keys are very easy to move (the board comes with a tool for moving the keys). And it can store 5 keymaps on the built in memory(so you can take your layout with you).

    Note: the software that comes with the board is buggy, so make sure to download driver version 2.10 from their site if you get the board.

    Last edited by sorenk (03-Dec-2007 07:39:42)

    "Things will get better despite our efforts to improve them" - Will Rogers
    "...even the dog doesn't think I'm a monster." - Humphrey Bogart in The Caine Mutiny (1954)

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