G.Moretti@massey.ac.nz (Giovanni Moretti) (03/22/91)
>> WHY DO MY ALT / CTRL / SHIFT keys "appear" to get stuck?
When I type fast on my PC periodically the keyboard seems to freeze
and it appears as though the PC has died - this annoyed me for about
a year.
Slowly the realization dawned that the PC itself hadn't died but the
keyboard had (?) and this eventually got modified into realizing that
the keyboard wasn't dead but the PC (or keyboard) thought that one of
the CTRL/ALT/SHIFT keys was still depressed (ie stuck down) when it
wasn't.
As I remember, the problem occurs only when I type fast.
Now when the keyboard dies, I:
press CTRL and try a normal letter key
press ALT and try a normal letter key
press LEFT SHIFT and try a normal letter key
press RIGHT SHIFT and try a normal letter key
Virtually always this clears the "Stuck"/Frozen problem. I thought
that it occurred because of the PC having been assembled out of bits
and pieces gathered from many sources. However when talking to our
software manager I found that his PC (bought as a single unit :-) has
done the same thing.
The motherboard is a LINGO (from Singapore) and the problem occurs
with both Phoenix and Award BIOS's and both 101 and 84 key keyboards
(all using the same motherboard).
What (If anything) can I do about this?
Any help would be appreciated.
Thanks
Giovanni
--
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Giovanni Moretti, Consultant | G.Moretti@massey.ac.nz, Pkt-ZL2BOI@ZL2BFJ
Computer Centre, Massey University| Ph 64 63 69099 x8398, FAX 64 63 505607
Palmerston North, New Zealand | QUITTERS NEVER WIN, WINNERS NEVER QUIT
------------------------------------------------------------------------------fisher@sc2a.unige.ch (03/25/91)
In article <1991Mar21.225509.10052@massey.ac.nz>, G.Moretti@massey.ac.nz (Giovanni Moretti) writes: >>> WHY DO MY ALT / CTRL / SHIFT keys "appear" to get stuck? > > When I type fast on my PC periodically the keyboard seems to freeze > and it appears as though the PC has died - this annoyed me for about > a year. > > Slowly the realization dawned that the PC itself hadn't died but the > keyboard had (?) and this eventually got modified into realizing that > the keyboard wasn't dead but the PC (or keyboard) thought that one of > the CTRL/ALT/SHIFT keys was still depressed (ie stuck down) when it > wasn't. > > As I remember, the problem occurs only when I type fast. > > [solution: strike the CTRL, ALT, LEFT SHIFT and RIGHT SHIFT keys] > > What (If anything) can I do about this? This was a common problem back in the days of the M24, with both keyboards (type 1, PC-like, and type 2, an "Olivette special" with F1 to F18 keys...). I had to dissasemble the keyboard driver (there was a conflict between WP 3.2 key assignments and the DOS 2.11 swiss-french driver), and I looked into this problem also. It turned out that it was purely hardware. Whenever three keys were depressed at once, and with some keys even only two, the keyboard would generate additional scan-codes (not randomly but unpredictable). There was talk at the time to use one of the "extra" keys of the "type 2" keyboard (CLEAR or HELP) to resotre the shift-states. BTW: it remains a mystery why the "legal" key-combinations worked... If you ran into the same problem, there is nothing to do. Whenever you type fast, you will depress the next key while (or even just before) you release the previous, and you'll end up with "random" scan-codes. If the code means "CTRL-depress", the driver will wait for a "CTRL-release" code to get out of "CTRL-state". I used the same solution you did (I learned to depress quickly each of the shift keys). You could also write a small TSR to clean the shift-state whenever you type a given key or a key combination, but is it worth the effort? Finally, you should try different, more robust keyboards. I switched to a IBM AT, and later to a HP Vectra, and never run into this again. Hope this helps, Markus Fischer, Dpt of Anthropology, Geneva CH