[Coco] CoCo MIDI Music Port schematics?

[John W. Linville]

I have the following:

CoCo MIDI Music Port
By GlenSide Color Computer Club
As authorized by Rulaford Research
Built by Brian Schubring

It is built around a 6850 ACIA, a 4MHz crystal, an opto-isolator,
some 74xx logic and a couple of parts I'm having trouble identifying
(18k31, 18k34).

The PCB is etched with this:

COCO-MIDI VER 1.1
GlenSide CCC '96
BY C.H REDONE BY BRIAN S.

Can anyone point me at a schematic and/or some documentation?
Perhaps there is an article in one of the CoCo-related magazines
(although '96 seems a bit late for that)?  I get the impression that
basically all the CoCo MIDI ports used the same basic design...?

Thanks,

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.