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From: bryce@hoser.berkeley.edu (Bryce Nesbitt)
Newsgroups: comp.sys.amiga
Subject: Re: Keyboard parallelogram fix?
Message-ID: <4047@zen.berkeley.edu>
Date: Wed, 30-Sep-87 05:24:16 EDT
Article-I.D.: zen.4047
Posted: Wed Sep 30 05:24:16 1987
Date-Received: Sun, 4-Oct-87 20:39:10 EDT
References: <482@esunix.UUCP> <2419@cbmvax.UUCP>
Sender: news@zen.berkeley.edu
Reply-To: bryce@hoser.berkeley.edu.UUCP (Bryce Nesbitt)
Organization: Center Tapped Solids, Inc.
Lines: 49

In article <2419@cbmvax.UUCP> grr@cbmvax.UUCP (George Robbins) writes:
>In article <482@esunix.UUCP> blgardne@esunix.UUCP (Blaine Gardner) writes:
>> Several months back George Robbins mentioned that he had a fix for the
>> A1000 keyboard's parallelogram bug...
>
>This parallelogram problem, aka the "frlom" problem or 2-key rollover occurs
>when three keys are depressed that share the same rows and columns in the
>keyboard matrix.... ....The keyboard can
>be upgraded with some A500 parts....
>I'll post some more information when they are readily available.

On the A1000 I'm typing upon, holding "f" and "r" then pressing either
"l" or "o" produces both "l" and "o".  Sure looked like both to the
keyboard!
On the A500 next door, holding "f" and "r" then pressing either "l" or
"o" produces nothing.

Typing "fro", holding each key down produces:

A1000	-	frlo
A500	-	fr

This does not represent real typing.  Typing "fro", holding each key,
then releasing the "f" produces:

A1000	-	frlo
A500	-	fro	;!!


Now for some blatant, unfounded, speculation:

It seems A500's keyboard processor has enough brains
to say "hey", "I can't figure out which key is down".  It then waits until 
the matrix un-blocks and collects the data.  Neat!  Good solution.
On the Amiga 1000, at least some of the keyboards use a Rockwell 6500/1.  
The 500 has a "MOS 6570-036".  Same thing with an "036" ROM in it?
Seems the 500 has a watchdog timer also.  Would to reset the keyboard if it
ever stopped scaning keys.  Hope it only does the keyboard and not the
computer too!

4 key rollover it is not.  "from", holding each key produces "frmo".

>George Robbins - now working for,	uucp: {ihnp4|rutgers|allegra}!cbmvax!grr

 
|\ /|  . Ack! (NAK, ENQ, SYN)
{o O} . 
 (") 	bryce@hoser.berkeley.EDU -or- ucbvax!hoser!bryce
  U	How can you go back if you have not yet gone forth?