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On Wed, Aug 17, 2011 at 1:42 PM, <meino.cramer@×××.de> wrote: |
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> Paul Hartman <paul.hartman+gentoo@×××××.com> [11-08-17 18:02]: |
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>> On Tue, Aug 16, 2011 at 10:01 PM, <meino.cramer@×××.de> wrote: |
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>> > Hi, |
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>> > |
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>> > I have attached an old keyboard (PS/2-connector) via an |
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>> > USB-PS/2-adaptor to my PC. |
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>> > |
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>> > When typing too fast (...) the three LEDs of the keyboard flashes |
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>> > and everything typed then is typed as if the CTRL-Key constantly |
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>> > locked (I am using the X-window-system with openbox as windowmanager. |
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>> > There is no session management.) |
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>> > |
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>> > It is possible to revert back to normal when I switch |
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>> > from X-windows to the Linux console (CTRL-ALT-F1) and back |
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>> > to X (CTRL-ALT-F7). |
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>> > |
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>> > My question is: |
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>> > What part (PC? Adapator? Keyboard?) gets out of sync here is |
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>> > "resetted" (somehow), while switching between console and |
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>> > X-windows? |
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>> > |
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>> > How can I reset the behaviour without switching? How can I |
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>> > prevent the behaviour completly? |
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>> |
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>> FWIW I have experienced that same behavior with several PS/2 to USB |
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>> adapters, in Windows, in Linux, etc. I think it's a common problem |
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>> with those adapters in general. I've never used one that didn't "go |
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>> crazy" a few times a day. |
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>> |
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> Hi Paul, |
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> |
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> after some recursive investigations :) via internet I found some |
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> interesting things: |
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> 1) Yes, your are completly right: It is the USB-PS2-adapter, which |
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> goes crazy. |
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> 2) No, you are wrong, the reason is different. |
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> ;) :) |
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> 3) The answer is 41.999998 (calculated by a P90). ;) |
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> |
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> The reason for stuck CTRL/SHIFT keys is a missing pull-up |
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> resistor from the clock and the data line to the +5V line |
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> of the PS2 connection. Or in other words: Adding these resistors |
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> seem to fix the problem in most cases. |
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> See the link below (which describes the process for a IBM Model M keyboard. Seems true |
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> for other old PS2 keyboards as mine, too): |
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> http://ps-2.kev009.com:8081/ohlandl/keyboard/modify_keyboard/Model_M_Modifications.html |
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> |
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> The PS2 goes crazy because the high level gets too low without the |
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> additonal pull up resistors. But the "origin of the reason" is not |
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> the adapter, but the low high levels of the old PS2 line as such. |
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> |
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> I did find these information that late (after posting to this list) |
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> by searching for informations about certain different usb-PS/2-adapter. |
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> Sorry, when answering the other half of my own question.... :) |
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|
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Very interesting info, it's good to know the real reason why it always |
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seems like a "universal" problem with those adapters. |
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|
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In the end, to solve my own problem, I bought two Unicomp keyboards |
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which are the same as the old heavy IBM keyboards but with USB |
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built-in. ;) |
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