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Path: utzoo!mnetor!seismo!rochester!kodak!gardner
From: gardner@kodak.UUCP (dick gardner)
Newsgroups: sci.electronics,comp.misc,comp.sys.cbm
Subject: Re: SmartWatctch Help
Message-ID: <848@kodak.UUCP>
Date: Mon, 11-May-87 08:44:17 EDT
Article-I.D.: kodak.848
Posted: Mon May 11 08:44:17 1987
Date-Received: Wed, 13-May-87 01:29:35 EDT
References: <849@killer.UUCP>
Reply-To: gardner@kodak.UUCP (dick gardner)
Organization: Eastman Kodak Co, Rochester, NY
Lines: 49
Keywords: Dallas Semiconductor SmartWatch C-128 6502
Xref: mnetor sci.electronics:690 comp.misc:502 comp.sys.cbm:432

In article <849@killer.UUCP> sentinel@killer.UUCP (The Sentinel) writes:
>-
>    Hello.  I recently picked up a Dallas Semiconductor SmartWatch, and
>installed it in my Commodore 128.  This is a "no-slot clock" which plugs
>into the board underneath a ROM, and is transparent until you need it.
>
>    However, I have a problem.  It won't do anything.  No matter what I do
>I can't access it.  All I have to go on is the manufacturer's data sheet,
>so I think I must me missing something which would be obvious to someone
>else.
>
>    So, has anyone had any experience with this chip in a 6502-based computer?
>Any help, suggestions, or sample code would be greatly appreciated.  Is there
>anything unusual about the bus structure of the C-128 (or 6502) which would
>cause ROM access to be carried out differently from, say, an 8088-based PC
>clone?
>

In order to use the Smartwatch, you must devote 1 byte of the ram contained
in the socket for use by the clock device.  You prepare to read/write to 
the clock by first reading the device to start the sequence, and then writing
the 64 bit code sequence of bits to the dummy clock location in ram.  You
are then able to read or write the clock values, but you must empty/fill
the entire 64 bit pattern.  You CANNOT selectively read/write any single
location.

I could mail you some 8051 code that works if you wish, or I can supply
you with the issue and date of an article that Steve Ciarcia wrote for
BYTE magazine (written in Basic, I think).

This is a really neat device that works quite well.  I am sure that there
is nothing special about the 6502 that prevents you from using it.
Just remember that it is only the least significant bit that transfers
information, and of course you must handle it a byte at a time, and shift,
and all that stuff.

I suspect that your trouble is in not doing the first read before beginning
the key sequence.  I know that was my problem when I first used this
device.  I placed several calls to Dallas Semi before getting it going.

Good luck.   Hope this info helps.

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   Dick Gardner -- Eastman Kodak Co.  Rochester, New York  14650
                   Phone: (716) 477-1002
                   UUCP: {allegra,seismo}!rochester!kodak!gardner
   "Research is what I do when I don't know what I'm doing"
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