Building a universal keyboard adapter

From: Eric J Korpela <>
Date: Mon Feb 7 12:48:57 2005

Hi All,

I've finally gotten fed up with my lack of space and the difficulty of
accessing machines stored in closets, so I've decided to that I need
to integrate every single machine into my PS/2 KVM setup. That way
digging through shelves in closets to find the machine I'm looking and
haul it out for use for will be a thing of the past.

Video is easy enough, since things are pretty standard. Essentially
I've got four kinds. 1) something that will work on an existing
multiscan monitor (>30 kHz H-scan, most workstations and PCs since the
late 80s) 2) Machines that require scan converters/line
doublers/flicker fixers (15-25 kHz H-scan, MDA/CGA/EGA, Amiga, Atari
ST color, Apple IIgs) 3) Machines that have NTSC video output (most
every pre-1984 micro) 4) Machines that have NTSC RF output.

Mice are also not that much of a problem. The protocols of serial
mice differ, but not so much that converters are hard to come by.
There are also machines that use direct quadrature inputs (Amiga,
Atari ST, MS bus mouse) but a single converter will handle all of
those with just changes to the pinout to support differing systems.
The only places I'm having problems with mice are where the protocol
is undocumented (like the AT&T 3B1 mouse), That and the PS/2 to ADB
converter doesn't seem to work too well with the Apple IIgs. Updates
are probably sent at too high a rate for the IIgs to handle.

Where I'm having the most trouble, and will probably have to come up
with my own solution, is in the keyboard interface. Serial keyboards
aren't much problem. I've already got ADB, Sun and SGI protocol
converters. The bigger problems are matrix keyboards (which ususally
have undocumented connectors). I'm thinking about using a BASIC stamp
to do the actual conversion from AT scan codes to whatever matrix the
keyboard represents, but that would require external serial support
since its serial interface is 9600 bps async and can't handle the
10-16 kbps that would come from the keyboard. Anyone have any better
(or cheaper, I really like cheaper) ideas?

Received on Mon Feb 07 2005 - 12:48:57 GMT

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