Path: utzoo!utgpu!water!watmath!clyde!att!ucbvax!agate!saturn!ssyx!sirkm
From: sirkm@ssyx.ucsc.edu (Greg Anderson)
Newsgroups: comp.sys.atari.st
Subject: Re: Midi ports
Message-ID: <4619@saturn.ucsc.edu>
Date: 25 Aug 88 17:27:23 GMT
References: <8808251416.AA06362@stark.LCS.MIT.EDU>
Sender: usenet@saturn.ucsc.edu
Reply-To: sirkm@ssyx.ucsc.edu (Greg Anderson)
Organization: UC Santa Cruz; Division of Social Sciences
Lines: 33

In article <8808251416.AA06362@stark.LCS.MIT.EDU> cpc@HOLMES.LCS.MIT.EDU writes:
>  When the ST receives a note (or, probably, anything) through MIDI IN,
>  it pipes it through to MIDI OUT.  My evidence is that when I hook both
>  cables between the ST and the synth, the synth reports that it is
>  *receiving* info whenever I play a noth on its keyboard.  The sound is
>  slightly different, and the number of voices is cut in half (because
>  every note is being played twice.  This has nothing to do with the
>  Dr.T sequencer, because it happens when I just turn on the ST.

The problem is probably in your MIDI _cables_.

Whenever the ST receives a note, it sends it out on the "Midi through"
port.  "What MIDI through port?" you might ask.  "I only see two MIDI ports;
out and in."  That's where the problem lies--there are only two physical
ports--MIDI through is crammed into the MIDI out port.

The MIDI standard only uses three of the five pins available on the MIDI
port.  One of these pins is ground, so someone at Atari realized that two
MIDI ports could be put on one physical connector.  If you want to make
use of MIDI through, you can build a special "T" cable that splits the
non-standard ST MIDI out/through into two standard MIDI cables.

Why does this cause problems with some cables?  Since the MIDI through pins
on a standard MIDI synth are unused, many "standard" MIDI cables short the
unassigned pins to their respective used pins.  (I'll explain why and how
if anyone cares;  suffice it to say that it's cheaper and easier.)  On a
standard MIDI port, this doesn't cause any problems.  On the ST's MIDI out
port, it can cause problems.

Such cables will also make MIDIMAZE non-functional.  If you ever have MIDI
problems on an ST, the first thing you should check is the cables.
Greg Anderson                     ||  The Temple of Zuul BBS:  (408) 462-3832
Social Sciences Computing, UCSC   ||  sirkm@ssyx.ucsc.edu