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From: hsu@cvl.UUCP (Dave Hsu)
Newsgroups: net.music.synth
Subject: Re: Re: MIDI
Message-ID: <93@cvl.UUCP>
Date: Mon, 25-Feb-85 23:18:05 EST
Article-I.D.: cvl.93
Posted: Mon Feb 25 23:18:05 1985
Date-Received: Fri, 1-Mar-85 07:45:15 EST
References: <3416@alice.UUCP> <8617@brl-tgr.ARPA>
Organization: Computer Vision Lab, U. of Maryland, College Park
Lines: 21

> > Also, as Dave Hsu pointed out,
> > the MIDI standard requires a current loop interface, hence an opto-
> > isolator.
> > 
> 
> Eh?  The schematics for the MPU show the lines to be balanced pairs.
> They are driven by convetional drivers, no optoisolaters are involved.
> 

Most odd.  Having seen several schematics and a number of Apple/Midi 
interfaces, there are most certainly opto-isolators involved.  And my ref.
books describe to the hook-ups as current-loop interfaces.  I'll dig up
exact references by Wednesday.


=Dave Hsu=                                       (301) 454-4526
ARPA: hsu@cvl  hsu@umd2                  USnail: Computer Vision Laboratory
CSNET: hsu@cvl                                   Center for Automation Research
BITNET: hsu@umd2                                 University of Maryland
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