Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!cbmvax!bj
From: bj@cbmvax.commodore.com (Brian Jackson)
Newsgroups: comp.sys.amiga.datacomm
Subject: Re: Help needed using modem with A1000.
Message-ID: <22249@cbmvax.commodore.com>
Date: 7 Jun 91 17:08:38 GMT
References: <755@ariel.ucs.unimelb.edu.au> <36000001@col.hp.com>
Reply-To: bj@cbmvax.commodore.com (Brian Jackson)
Organization: Commodore, West Chester, PA
Lines: 35

In article <36000001@col.hp.com> davem@col.hp.com (Dave K. Martin) writes:
>I would suspect that the modem cable is causing your problems.  There are some
>non standard signals present on the Amiga's serial port.  Probably your modem 
>is shorting one of the Amiga power outputs, +5 or +12 volts, to ground.  
>The A-1000 power supply is robust enough to allow a short on one section (using
>a long length of small diameter wire) and still keep the computer operating.
>
>I don't have my Amiga hardware manual handy so I can't tell you which pins they
>are.  Try using a different cable that only connects pins 2, 3, 4, 5, 6, 7, 8,
>20 and 22.  These should cover everything your modem wants.
>
>The RS in RS-232 stands for 'Recommended Standard' and virtually 
>every manufacturer changes the pinouts on the lesser used pins for their own 
>purposes.  The A-1000 has some neat signals appearing on the serial port though.
>I can't remember them off the top of my head but I'm pretty sure that both 
>sound channels are present along with the +5, +12 and -12 volt power sources.
>
 ...

>davem

The 1989 Hardware manual says that the only serial pins that your
modem should touch are pins 1-8, and 20.  The especially dangerous
ones are pins 14,21 and 23 (they are power sources.)  On the A1000
pin 25 is a 'buffered system reset' which, if triggered by the modem,
can/will reboot the machine. The Supra 2400 did it to mine; that's 
how I discovered that I had unwittingly switched cables to a 'standard'
serial cable.)

Brian

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 | Brian Jackson  Software Engineer, Commodore-Amiga Inc.  GEnie: B.J. |
 | bj@cbmvax.cbm.commodore.com    or  ...{uunet|rutgers}!cbmvax!bj     |
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