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From: gamet@erg.sri.com (Thomas Gamet)
Subject: keyboard specifications
Message-ID: <1993Apr18.010541.6866@erg.sri.com>
Sender: news@erg.sri.com
Organization: SRI International, Menlo Park, CA
Date: Sun, 18 Apr 93 01:05:41 GMT
Lines: 35

To all hardware and firmware gurus:

My current home project is to build a huge paddle keyboard for a 
physically handicapped relative of mine.  My goal is for this keyboard
to look exactly like an AT sytle keyboard to its host system.
This will be a highly endowed keyboard with a Little PCL from Z World
at its heart.  The only thing I lack is detailed information on the
hardware signaling that the 486 (with  Windows 3.1  and DOS 5.0) will be 
expecting.  My project is independant of Windows, my hope is that some of
you fellow Window's users/programmers will recognize what I need and be 
willing to point me in the right direction. 

I have The Winn L. Rosch Hardware Bible (2nd edition).  The HB gives
most (if not all) of the information I will need concerning scan codes 
and even a wire diagram for the PS/2 style connector I will need, but it 
leaves a number of important questions unanswered.
1.  Is it synchronous or asynchronous serial communication?  I'm
    guessing synchronous since the host is providing a clock.  In either
    event, how is the data framed?
2.  Is it half-duplex or truly one way?  I'm guessing half-duplex
    since the host can turn LEDs on and off.
3.  Are there any chipsets available for communicating with the "AT
    keyboard standard" (other than by cannibalizing a real keyboard)?

If anyone knows of a book or article (or any other written source of
information) on the above, please advise me at gamet@erg.sri.com.
Whatever I do it must be safe for I cannot afford to replace the 486 in
the event of a booboo.

Thank you for your time.
Danke fuer Ihre Zeit.

Thomas Gamet (gamet@erg.sri.com)
Software Engineer
SRI International
