Xref: utzoo comp.sys.mac.hardware:4344 comp.sys.mac.misc:1335 Path: utzoo!attcan!uunet!decwrl!sgi!llustig!xanadu!kari From: kari@xanadu.com (Kari Dubbelman) Newsgroups: comp.sys.mac.hardware,comp.sys.mac.misc Subject: Re: Anyone seen these keyboard problems ? Summary: Suspect keyboard scanning chip and debouncing Message-ID: <1990Jul13.042935.28317@xanadu.com> Date: 13 Jul 90 04:29:35 GMT References: <1990Jun26.193915.18901@calgary.uucp> <1990Jun30.183958.12053@terminator.cc.umich.edu> Organization: TeraCons, Cupertino Lines: 29 Gavin Eadie writes: I too, and two of my colleagues, have been having trouble with keyboard stoppage as we type certain sequences fast. The sequence in particular is "stop" (which is typed a lot into VersaTerm for our mainframe software) and the final "p" sometimes doesn't appear. If you notice, and type "p" again it still doesn't work - you need to type something else to 'unjam' the keyboard. I have observed very similar problems with at least two different kinds of terminals. In my case, the terminal would choke if I typed the word "printf" too quickly. This is a bummer if you are a C programmer. These were dumb terminals, not computers. They don't contain much. My suspicion is that the keyboard scanning chip is scanning the keyboard matrix too slowly. This scanning frequency probably is a tradeoff between getting the problem we are discussing and getting key bounces. The layout of the keyboard will determine which combinations are poisonous. If you are adventurous, there might be ways to speed the scanning rate up by a hardware mod, at least for dumb terminals. Maybe not for Mac's. -- Kari Dubbelman, TeraCons, PO Box 160668, Cupertino, CA 95016-0668 (408) 374-8863 until 1-Jun-1990, after that use (408) 266-8241 Kari@Xanadu.com uunet!xanadu!kari CIS:75130,24 AppleLink/GEnie/MCI/PAN:TeraCons *** The first human to get to be a million years old has already been born ***