Caught on tape by an undercover CIA agent were Sundeep Goel's words:
 This is the circuit for the MIDI INPUT.
                                      +-----> To pin 5 of 'D' connector
                                      |
 To pin 15 of 'D' connector  To pin 9 of 'D' 
con
                                |     |     |       |
                                |6    |5    |4      \
                              +---------------+     /  220 ohm
                              |     PC900     |     \  resistor
                              |      or       |     /
                              | o  HP 6N138   |     |
                              +---------------+     +------> To pin 6 of 
C900
                                |1    |2    |3
                                |     |     |
                                \     |     +----->  No connection
                        220 ohm /     |
                       resistor \     |
                                /     +-----> To pin 5 of DIN connector
                                |
 To pin 4 of DIN connector <----+
 Don't overlook the two 220 ohm resistors.
 Also, for cables longer than a few feet, connect pin 2 of the DIN to pin
 5 of the 'D' connector.
 The output circuit is much simpler.
                                   220 ohm resistor
 To pin 12 of 'D' connector  To pin 5 of DIN
 con.
 To pin 15 of 'D' connector  To pin 4 of DIN
 con.
 Also, for cables longer than a few feet, connect pin 2 of the DIN to pin
 5 of the 'D' connector.
 This circuit has been built and tested by me, using Voyetra's SPJr, and
 a cheap-o Casio keyboard. The input and output do work as shown here, but I
 don't have any other MIDI devices to use to test using more than 1 output
 device. Theoretically, it should work fine, but it has not been tested.
 The chances of hurting anything by trying is slim and none.
 This circuit DOES work, but I make no guarantees, nor will I be
 held responsible for any damages you may cause from your use of
 this information.
 If you have any questions, or would like to buy one already built for you,
 I can be contacted on:
 The Lighthouse BBS (207) 255-3700   (username is Ronald Davis)
 The Music Studio BBS (708) 351-0288 (username is Volstagg)
 From: bl562@cleveland.Freenet.Edu (Gary P Gabriel)
 Subject: Re: Sound Blaster MIDI port
 Date: 20 Feb 92 02:33:01 GMT
 I built CHEAPMID board of which you speak.  I could not get it to work.
 The Sharp chip was unavailable the the 6N26 is not a direct replacement
 for the Sharp (PC900?) chip.  I found another set of plans,  built it,
 and have used it with relative success.  If I can remember where I
 got it I will post it.
 From: kdrenard@smoke.brl.mil (Kenneth D. Renard)
 Subject: Re: SoundBlaster MIDI port
 Date: 20 Feb 92 13:41:38 GMT
	I believe there is a mistake in the MIDI-out portion of this 
 design in that pin 15 from the D-connector is the MIDI-in (see SB manual).
 Pin 12 should go through the 220 ohm resistor to DIN pin 5 as stated in the
 designs.  I'm pretty sure that DIN pin 4 should be +5 volts.  Connect it to
 pin 9 (instead of pin 15) from the D-connector through a 220 ohm resistor.
     I could not find a PC900 or HP 6N138 opto-isolator, but Mouser
 electronics crossed it to an NTE 3093 which happens to be an 8-pin DIP.
 Mouser was very helpful and sent me the pin-out which shows that 2 of the
 pins are not used.  All I need now is the pinout for the HP 6N138 to
 compare the two.
	I just completed another design for the MIDI connector, but
 haven't worked the bugs out yet.  I will try to post it soon.
 Ken Renard
... Go far enough and you will reach a place where the sea runs underneath
--- PPoint 2.06
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