Messages in this thread | | | Date | Mon, 11 Aug 1997 14:35:38 +1000 (EST) | From | Marcus Berglund <> | Subject | Re: Keyboard error |
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On 11 Aug 1997, Linus Torvalds wrote:
[...SNIP...] >The keyboard signals the error, and there is nothing the driver can do >about it. So yes, the answer is "don't do that, then". > >The deeper reason for the error can be found in how the keyboard >physcially scans which keys are pressed. For reasons of economy, most >keyboards have a simple "scanning array" where a keypress shorts one >array corner (*). Depending on how the array is set up, pressing >multiple keys will not always work - and the exact keys that result in >breakage depend on the topology of the scanning array. > >Many multi-key-presses will create a "shadow key press" (so when you >press three keys, the keyboard controller will actually think that >you're pressing four keys, and I suspect that the keyboard controller >just notices that two keys changed simulataneously and will consider >this an error. > >The keyboard array is usually set up in such a way that the "normal" >keys that are often pressed together (alt, shift, cursor keys etc) >create as few of these shadows as possible, but you've obviously found >one of them. I suspect that you'll easily find more by just pressing >lots of keys at the same time.. [...SNIP...] > > Linus >
Linus is on the right track here, basically some more expensive keyboards can take upto 7 keypresses (or more) at once, I found this out on a friends keyboard, two players on one computer/keyboard setup, and generally on cheap keboards you can get away 3 keypresses before you get a keyboard "lock", does anybody remember how DOS/BIOS complains: <bleep><bleep><bleep><bleep>....
My keyboard does 6 keys bofore it stops sending anything (no errors, about AUS$100)
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