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#1
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N-Key Rollover keyboard
What's the opposite of N-Key Rollover? -- @~@ Remain silent. Nothing from soldiers and magicians is real! / v \ Simplicity is Beauty! May the Force and farces be with you! /( _ )\ (Fedora 17 i686) Linux 3.6.10-2.fc17.i686 ^ ^ 18:21:01 up 2 days 12:34 0 users load average: 0.00 0.01 0.05 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa |
#2
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N-Key Rollover keyboard
On 3/01/2013 9:38 PM, Man-wai Chang wrote:
What's the opposite of N-Key Rollover? I meant the name for that... -- @~@ Remain silent. Nothing from soldiers and magicians is real! / v \ Simplicity is Beauty! May the Force and farces be with you! /( _ )\ (Fedora 17 i686) Linux 3.6.10-2.fc17.i686 ^ ^ 18:21:01 up 2 days 12:34 0 users load average: 0.00 0.01 0.05 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa |
#3
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N-Key Rollover keyboard
On Jan 3, 8:38*am, Man-wai Chang wrote:
What's the opposite of N-Key Rollover? If you go to a keyboard forum (like geekhack.org), they will use terms like 2-key rollover or 6-key rollover, to refer to non-N-key (aka, 10-key) rollover scenarios. Nearly all membrane keyboards are really just 2-key rollover. Note that even if you have an N-key rollover keyboard, the USB specification for keyboards has a 6 key limit. The only way to break the 6-key rollover limit is to use the PS/2 port, or for the keyboard to fake it by registering itself as multiple keyboards (my home keyboard, the Noppoo Choc Mini, pretends it is 2 USB keyboards, in order to get N-key rollover). -- // T.Hsu |
#4
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N-Key Rollover keyboard
On Thursday, January 3, 2013 8:50:20 AM UTC-7, Man-wai Chang wrote:
What's the opposite of N-Key Rollover? I meant the name for that... N-key lockout. Feels awful, like typing on an old mechanical typewriter that jams if more than 2 keys are pressed at once. I once played around with an unencoded keyboard wired to a couple of I/O ports, and the feel of the typing could be changed a lot by changing the scanning software. My first attempt gave n-key lockout, but by storing just the previous decoded key I got 2-key rollover, which felt a lot better and for all practical purposes as good as n-key rollover. By storing the whole key matrix, I got n-key rollover but sometimes with phantom keys. I was able to fix that problem in software (sometimes lock out if more than 2 keys pressed at once) or by wiring a diode in series with each key switch. BTW a simple hardware decoder that scans the matrix will automatically give 2-key rollover, and I think it gives reliable n-key rollover if diodes are added. |
#5
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N-Key Rollover keyboard
On Thu, 03 Jan 2013 21:38:30 +0800, Man-wai Chang
put finger to keyboard and composed: What's the opposite of N-Key Rollover? FYI, here is the specification for the original IBM PC-AT keyboard: http://www.users.on.net/~fzabkar/PC-AT/IBM_AT_keybd.txt "The keyboard is able to detect all keys that are pressed, and their scan codes will be sent to the interface in correct sequence, regardless of the number of keys held down." Not all keyboards conform to the original spec. Mine doesn't: http://groups.google.com/group/comp....rnum=11&lnk=nl - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
#6
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N-Key Rollover keyboard
On Thursday, January 3, 2013 8:53:54 AM UTC-7, Paul wrote:
Most music keyboards use isolation diodes in their keyboard matrix to implement full n-key rollover (sometimes abbreviated NKRO), making them immune to both key ghosting and key blocking. However, to reduce cost and design complexity, most keyboards do not isolate all keys in this way. Instead, they use a matrix of key switches, without any isolation diodes, that assumes that only a limited number of keys will be held down at any given time." ******* I built my own keyboard, and fitted a 1N914/1N4148 switching diode to each keyswitch, to prevent ghosting and allow more than one key to be depressed without losing it. I think on my keyboard, that's to prevent a fast typist from having problems when the first key isn't completely released, when the second key is starting to make contact. I'm not sure my keyboard controller would support "mashing" a whole bunch of keys. It probably did not have a buffer deep enough to allow that. I once had a PC keyboard with a diode in each switch, and I think it gave perfect n-key rollover (or at least 16-key rollover -- 2 people). Also the keys felt great, and the key caps were 2-color molded so the markings couldn't rub off. Unfortunately it had only 83 keys, meaning it was only for XT computers. The old IBM model F 84-key AT keyboard passes the THE QUICK BROWN FOX JUMPS QUICKLY OVER THE LAZY DOG TEST (both shift keys held down), despite not having a diode in each switch, but the IBM model M 101-key does not. |
#7
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N-Key Rollover keyboard
N-key lockout. Feels awful, like typing on an old mechanical
typewriter that jams if more than 2 keys are pressed at once. Thanks! Good analogy here.. -- @~@ Remain silent. Nothing from soldiers and magicians is real! / v \ Simplicity is Beauty! May the Force and farces be with you! /( _ )\ (Fedora 17 i686) Linux 3.6.10-2.fc17.i686 ^ ^ 18:21:01 up 2 days 12:34 0 users load average: 0.00 0.01 0.05 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa |
#8
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N-Key Rollover keyboard
Thank you all for the replies! -- @~@ Remain silent. Nothing from soldiers and magicians is real! / v \ Simplicity is Beauty! May the Force and farces be with you! /( _ )\ (Fedora 17 i686) Linux 3.6.10-2.fc17.i686 ^ ^ 18:21:01 up 2 days 12:34 0 users load average: 0.00 0.01 0.05 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa |
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