Paul Hartman <[email protected]> [11-08-17 21:08]: > On Wed, Aug 17, 2011 at 1:42 PM, <[email protected]> wrote: > > Paul Hartman <[email protected]> [11-08-17 18:02]: > >> On Tue, Aug 16, 2011 at 10:01 PM, <[email protected]> wrote: > >> > Hi, > >> > > >> > I have attached an old keyboard (PS/2-connector) via an > >> > USB-PS/2-adaptor to my PC. > >> > > >> > When typing too fast (...) the three LEDs of the keyboard flashes > >> > and everything typed then is typed as if the CTRL-Key constantly > >> > locked (I am using the X-window-system with openbox as windowmanager. > >> > There is no session management.) > >> > > >> > It is possible to revert back to normal when I switch > >> > from X-windows to the Linux console (CTRL-ALT-F1) and back > >> > to X (CTRL-ALT-F7). > >> > > >> > My question is: > >> > What part (PC? Adapator? Keyboard?) gets out of sync here is > >> > "resetted" (somehow), while switching between console and > >> > X-windows? > >> > > >> > How can I reset the behaviour without switching? How can I > >> > prevent the behaviour completly? > >> > >> FWIW I have experienced that same behavior with several PS/2 to USB > >> adapters, in Windows, in Linux, etc. I think it's a common problem > >> with those adapters in general. I've never used one that didn't "go > >> crazy" a few times a day. > >> > > Hi Paul, > > > > after some recursive investigations :) via internet I found some > > interesting things: > > 1) Yes, your are completly right: It is the USB-PS2-adapter, which > > goes crazy. > > 2) No, you are wrong, the reason is different. > > ;) :) > > 3) The answer is 41.999998 (calculated by a P90). ;) > > > > The reason for stuck CTRL/SHIFT keys is a missing pull-up > > resistor from the clock and the data line to the +5V line > > of the PS2 connection. Or in other words: Adding these resistors > > seem to fix the problem in most cases. > > See the link below (which describes the process for a IBM Model M keyboard. > > Seems true > > for other old PS2 keyboards as mine, too): > > http://ps-2.kev009.com:8081/ohlandl/keyboard/modify_keyboard/Model_M_Modifications.html > > > > The PS2 goes crazy because the high level gets too low without the > > additonal pull up resistors. But the "origin of the reason" is not > > the adapter, but the low high levels of the old PS2 line as such. > > > > I did find these information that late (after posting to this list) > > by searching for informations about certain different usb-PS/2-adapter. > > Sorry, when answering the other half of my own question.... :) > > Very interesting info, it's good to know the real reason why it always > seems like a "universal" problem with those adapters. > > In the end, to solve my own problem, I bought two Unicomp keyboards > which are the same as the old heavy IBM keyboards but with USB > built-in. ;) >
(my question is based only on curiosity...) Are the Unicomp Model Ms of the same quality and tactile/audible feeling as the original IBM model Ms? Best regards, mcc
