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From: grr@cbmvax.UUCP (George Robbins)
Newsgroups: comp.sys.amiga
Subject: Re: Keyboard parallelogram fix?
Message-ID: <2489@cbmvax.UUCP>
Date: Wed, 14-Oct-87 08:26:34 EDT
Article-I.D.: cbmvax.2489
Posted: Wed Oct 14 08:26:34 1987
Date-Received: Fri, 16-Oct-87 01:18:38 EDT
References: <482@esunix.UUCP> <2419@cbmvax.UUCP> <4047@zen.berkeley.edu>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 35

In article <4047@zen.berkeley.edu> bryce@hoser.berkeley.edu.UUCP (Bryce Nesbitt) writes:
> 
> 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!

The MOS 6570 is pretty much the same thing as the Rockwell 6500/1.  The
version used for the A1000 US keyboard uses the -32 ROM code, while the
A500 uses the -36 ROM code.  Other codes are probably MOS Technology OEM
chips.  The watchdog timer was added in response to a problem with early
A1000 keyboards locking up.  This was attributed to static discharge,
since they seemed to work ok until you touched them.  Unfortunatly we had
the same problem on the A500, and everybody knows that there's no static
electricity in Pennsylvania!  Actually, it seems that it was a thermal
problem with the onboard oscillator getting flakey when the chip warmed up.
A couple capacitors stabilized things and on examination, somebody had
slipped the same fix into the A1000 keyboard, even though it didn't show
up on the "official" schematics.  Hard to imagine, but the processor must
really work hard operating all those keys 8-).

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

Oh well, it's only supposed to be 2 or 3 key rollover with intelligent
handling of matrix amibguities.
-- 
George Robbins - now working for,	uucp: {ihnp4|rutgers|allegra}!cbmvax!grr
but no way officially representing	arpa: out to lunch...
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)