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From: burris@ihopa.UUCP (David Burris)
Newsgroups: net.music
Subject: Re: MIDI (Musical Instrument Digital Interface) developments
Message-ID: <147@ihopa.UUCP>
Date: Thu, 26-Jan-84 16:35:15 EST
Article-I.D.: ihopa.147
Posted: Thu Jan 26 16:35:15 1984
Date-Received: Sat, 28-Jan-84 01:43:29 EST
References: <146@ihopa.UUCP> <422@pyuxn.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 106

I spoke to Bob Moog about a month ago at a seminar (by the way, he
no longer owns Moog Music) and he said that Moog is currently adding
a true MIDI interface to its new synths. and that a retrofit kit
should be available for the Memory Moog in the near future.

The Roland DG MPU-401 is the interface I've chosen to use with my
combination of instrument and computer. I am already in the
beginning stage of development for a software package in C language.
I intend to develop composition, editing, record, playback tools.
These may or may not be released to the public domain.

I don't know how much detail on the MIDI I can give without
violating the copyright by the International MIDI User's Group.
I will give a brief description. For more information, contact:

IMUG
8426 Vine Valley Dr.
Sun Valley, CA 91352
(213)-768-7448

MIDI Hardware:

	The interface operates at 31.25 Kbaud (+/- 1%) asyncronuous
	start bit, 8 data bits, and stop bit

	1.5 ma. current loop with receiver opto-isolated and
	turn-on current < 5 ma. & rise/fall times < 2 micsec.

	5 pin DIN connector for interconnection. 50' maximum length
	The cable shall be sheilded twisted pair, with the sheild
	connected to pin 2 at both ends.

Data Format:

	MIDI communication is acheived through multi-byte messages
	consisting of one status byte followed by one or two data
	bytes, except for real-time and exclusive messages.

	Message Types:
		I. Channel
			a. voice
			b. mode
		II. System
			a. common
			b. real-time
			c. exclusive

	Data Types:
		I. Status bytes
			a. running status
			b. unimplemented status
			c. undefined status
		II. Data Bytes

Channel Modes:

	Omni - when on allows voice messages to be received
		in all voice channels without discrimination
		when off messages are received only in the
		selected channels

	Poly - when on any number of voices may be allocated
		by the receiver's normal voice assignment algorithm
		when off (Mono) the assignment of voice is one
		voice/voice channel

	Omni and Poly/Mono are independent for a total of four
	modes.

Status Bytes Summary:

	Channel voice:
		note on/off
		key pressure/after-touch
		control change
		channel pressure/after-touch
		pitch wheel change

	Channel mode:
		local control on/off
		all notes off
		Omni mode on/off
		Mono/Poly mode

	System messages:
		system exclusive
			these messages are determined by the
			manufacturer of the particular device
			they should be publiched by the manufacturer
		system common
			song position counter
			song select
			tune request
			end-of-exclusive message
		system real-time
			timing clock
			start
			continue
			stop
			active sensing
			system reset
-- 
	Dave Burris
	..!ihnp4!ihopa!burris
	AT&T Bell Labs, Naperville, Il.