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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!bbn!usc!pollux.usc.edu!addison
From: addison@pollux.usc.edu (Richard Addison)
Newsgroups: comp.sys.amiga.tech,comp.sys.amiga
Subject: Re: MIDI Problems on A1000
Summary: The answer you seek lies within
Keywords: MIDI,Serial port,RS-232
Message-ID: <17138@usc.edu>
Date: 10 May 89 04:12:48 GMT
References: <12517@shamash.cdc.com>
Sender: news@usc.edu
Reply-To: addison@pollux.usc.edu (Richard Addison)
Followup-To: comp.sys.amiga.tech
Organization: University of Southern California, Los Angeles, CA
Lines: 29

In <12517@shamash.cdc.com> jwabik@shamash.cdc.com (Jeff Wabik) writes:
>Hi ..  I'm having some problems getting MIDI gear running with my A1000..  
>Here's the scoop.  
 :
 :
>I am using a standard null-modem cable for the serial attachment of the 
>A1000 to the MIDI Interface.

The problem is that your MIDI Interface box needs a super-set of the
"standard" RS-232 serial port signals.  In particular it needs +5V (pin 21)
and -5V (pin 14) to power the signal converters.  Thus you need a cable
that connects at least pins 2, 3, 7, 14, and 21 straight through from the
back of your 1000 to the MIDI Interface box.  You may need other signals
for whatever you connect on the pass-thru.

Now, if you had a 500 or 2000 connected to a MIDI Interface box designed for
a 500 or 2000, you would need +12V (pin 9) and -12V (pin 10) for power.

If you had a 500 or 2000 and wanted to connect a MIDI Interface box designed
for a 1000, you would also need a couple of resistors and Zener diodes to
go from the +/-12V on the serial port of the 500/2000 to the +/-5V expected
by the MIDI box.

Hope this helps,

Richard Addison
"This is only an emergency.  If this had been an actual test we would
have required that you bring a number 2 pencil.  We now return you to
your regularly scheduled programming."