Xref: utzoo comp.sys.mac:24606 rec.music.synth:5641
Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!killer!sp
From: sp@killer.DALLAS.TX.US (Steve Parker)
Newsgroups: comp.sys.mac,rec.music.synth
Subject: Re: DIY MIDI interface?
Summary: DYI Mac MIDI
Keywords: MIDI
Message-ID: <6636@killer.DALLAS.TX.US>
Date: 3 Jan 89 02:41:18 GMT
References: <817@ttrdf.UUCP>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 18

In article <817@ttrdf.UUCP>, fjo@ttrdf.UUCP (Frank Owen ) writes:
> 
>   Has anyone figured out how to kludge up a Do-It-Yourself MIDI interface
> for the Macintosh? It seems that the one Apple sells has practically no 
> hardware, and should be a snap to build. Is this correct?

Yea, pretty much.  The one I made cost me only about $10 since I had a few
scrap parts.  The only trick is you have to pump a 500k/1M/2M (depending on
software) clock signal back into the ext clock line, since there is no way
to divide the internal clock in the SCC to get 31.25k baud.  Also, you DO
have to use those pc900 optos on the inputs, garden-variety optos are simply
not fast enough.

I think there was an old issue of Dr. Dobbs (not positive) that had a schematic
for a mac interface in it.  If you write me (and aren't in a hurry) I can try
to dig up the exact reference.

- Steven Parker (sp@killer.Dallas.TX.US)