From: davem@col.hp.com (Dave K. Martin)
Date: Fri, 7 Jun 1991 13:39:52 GMT
Subject: Re: Help needed using modem with A1000.
Message-ID: <36000001@col.hp.com>
Organization: HP Colorado Springs Division
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!hp-col!col!davem
Newsgroups: comp.sys.amiga.datacomm
References: <755@ariel.ucs.unimelb.edu.au>

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.

I'll probably hear from hundreds who have used a 25 line cable with no 
problems :-) .  Actually, I've done it myself but only on a modem that left all 
of the pins that it didn't care about unterminated.

Hope this is helpful.............
davem