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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

2295.0. "Midi Spec Sources?" by MINDER::GLASSUP (nomads are people too!) Thu Mar 22 1990 11:28

You may think I'm a little crazy; Paul Kent, the guy who told me 
about this Conference, says my wishes are perverse but I can 
cope.

I have a desire to write a rather specialised Sequencer - too 
little room to explain here - and I'd like to do it on an IBM 
Compatible MS-DOS machine.  The programming is no problem (ho ho) 
'cos I have a pet freak who can only communicate with MS-DOS 
Machines; humans are too variable and have emotions.

So I have two questions:

1	 Where do I get a copy of the Latest MIDI Specifications 
         from: the only address I have is

	 International Midi Association
	 11857 Hartsbrook Street
	 North Hollywood, CA 91607

	 Is that right?

2	 Where do I get the hardware to plug into the PC - like 
         the Card with the Midi plugs/sockets?  Or do I have to 
         make 'em myself and if so HOWWWWWWWWW?

Just a point; so far I haven't understood anything but the words 
in this Conference; the Sentences just don't add upto me.  This 
is not a criticism, just a warning that as far as Computer Music 
is concerned, I'm stupid!

Regards,

Brian G
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2295.1This is a DIN cable, can you say that?TOCATA::PICKETTDavid - Beware of the dogma.Thu Mar 22 1990 18:296
    Dunno about the address, but you may wish to consult the book 'MIDI for
    Musicians' by Craig Anderton. It has the MIDI spec as an appendix. The
    spec hasn't changed a lot since rev 1.0. The rest of the book is all
    but worthless.
    
    dp
2295.2part 2...TOCATA::PICKETTDavid - Beware of the dogma.Thu Mar 22 1990 18:4312
    Oh yeah, and part 2....
    
    According to an ad in EM 3/90 pg56 
    
    PC MIDI Card $119 from Music Quest  214-881-7408
    
    I cannot vouch for this, but I remembered the ad, and it looks like 
    what you need. Also, you can consult Byte mag from a few years back,
    they had a two part article on building your own IBMPC MIDI card.
    Fairly cheap, as I recall.
    
    dp
2295.3Do not pay listSTAR::NORCOTTWakarimasu ka?Fri Mar 23 1990 00:368
RE:    
    PC MIDI Card $119 from Music Quest  214-881-7408
   
Get the card, I have one and it works great.  Do not pay full price,
get it mail order from Soundware (800-333-4554) for $99.

Bill Norcott

2295.4what are you gonna write, anyway?SWAV1::STEWARTAs a matter of fact, it's all darkFri Mar 23 1990 18:0118
>	2	 Where do I get the hardware to plug into the PC - like 
>	         the Card with the Midi plugs/sockets?  Or do I have to 
>	         make 'em myself and if so HOWWWWWWWWW?


	Another alternative for this might be from MusicQuest (??)...I
	forget the actual name of the outfit.  I bought my MPU-401 clone
	board (the Roland MPU-401 is the original and default standard
	for PC clone MIDI interfaces) from these guys and got a real
	stupid sequencer as part of the deal.  The only reason I mention
	these guys at all is that they also offer a C programmers toolkit
	for writing your own stuff.  Might give you a head start on your
	project.  Check the back pages of EM.  If you can't find them I
	could be persuaded to sell you my virgin copies...I've never had
	the time/inclination to look at the stuff.

	P.S. the board I got from these guys doesn't do tape sync, 
	either...fine print in the back of one of the manuals
2295.5MIDI current-loop spec, please?CTHULU::YERAZUNISIconoclasm as a way of life...Tue Oct 23 1990 21:4417
    
    A quick question to anyone who happens to have a MIDI 1.0 spec at
    their fingertips:
    
    I) MIDI inputs are defined as a current-loop; typically an LED input to an
    optoisolator.  What is the expected minimum impedance (i.e. is there an
    inline resistor?)
    
    II) MIDI outputs are defined as current loop drivers; what's the
    required minimum/maximum voltage and min/max current?  Or do they 
    just give an op-amp part and an in-the-line resistor?
    
    
    Reason I ask: I wanna build a MIDI "Star Coupler" and I wanna build
    it cheap.  So what if it loses a few notes once in a while... :-)
    
    	-Bill
2295.6This help?WEFXEM::COTELight, sweet, crude...Tue Oct 23 1990 23:1127
    
>    A quick question to anyone who happens to have a MIDI 1.0 spec at
>    their fingertips:
 
    Just happen to have the specs right here...
       
>    I) MIDI inputs are defined as a current-loop; typically an LED input to an
>    optoisolator.  What is the expected minimum impedance (i.e. is there an
>    inline resistor?)
 
    There's a 220ohm resister between pin 4 of the MIDI in and PIN 1 of the
    opto. (Typically a Sharp PC-900)
       
<    II) MIDI outputs are defined as current loop drivers; what's the
    required minimum/maximum voltage and min/max current?  Or do they 
    just give an op-amp part and an in-the-line resistor?
    
    The spec defines the circuit as 5mA current loop, optos should require
    less than 5mA to turn on (logical 0). Rise and fall times <2usec.
    +5V running thru a 220ohm resister. No min/max voltage given.
    
    Edd
    
    Reason I ask: I wanna build a MIDI "Star Coupler" and I wanna build
    it cheap.  So what if it loses a few notes once in a while... :-)
    
    	-Bill
2295.7The definitive answer.EICMFG::BURKEJim Burke, @UFCWed Oct 24 1990 22:019
    ...hardware expert speaking (short burnt fingers, note)...
    
    The diagram I have has a +5v going into (coming out of) the MIDI OUT
    port. And there's a 200 Ohm doobrie inbetween.
    
    Any more questions Bill: don't be afraid to ask (!)
    
    Jim
    
2295.8So far, so good.CTHULU::YERAZUNISMay the moon light your way, till the wind sets you free.Thu Oct 25 1990 20:587
    So, electronically speaking, the MIDI output port ought to look like
    a "perfect" 5 volt source with a 220 ohm resistor in series, and a 
    MIDI input port ought to look like a 220 ohm resistor?  
    
    Or do I have one too many 220 ohm resistors?
    
    	-Bill
2295.9WEFXEM::COTELight, sweet, crude...Thu Oct 25 1990 21:2420
                                                          o +5V
    midi in                                  |-------     |
                                            2|      |6    | 270ohm
    pin 5----------------------------o-------|      |-----+/\/\/\
                                     V IN914 |PC900 |            |
                                     + (D1)  |      |-----+------+--->UART
    pin4-------------------/\/\/\/---o-------|      |     |
                           220ohm           1|---+---     |
                                                 |5       V to thru
                                               -----
                                                ---
                                                 -
    midi out
                       220ohm
    +5V---------------/\/\/\/------Pin4
                |
               ||------------------pin2 (to shield)
                |
    from UART----------/\/\/\/-----pin5
                        220ohm
2295.10And what does "idle" sound like?CTHULU::YERAZUNISYou can't fall off the floor.Fri Oct 26 1990 13:487
    OK, thanks; it seems that there's a total of 660 ohms in the line- one
    on each leg of the transmitter, and one in the reciever.  No problem!
    
    Now, is the "idle" condition with no current flowing, or with current
    flowing?  (a 1 or a 0 coming out of the UART) ?
    
    	-Bill