rgc@wam.umd.edu (Ross Garrett Cutler) (05/20/91)
Hello *, I've seen numerous questions on the net in the last several weeks on how to hook up a MIDI device to the NeXT. This should probably go in the FAQ since a lot of users might want to know this... Personally, I called NeXT several times about this and talked to numerous tech people; no one knew how to do it except for $500 (for an expensive MIDI adapter)! Even worse, they said they'd call back after they investgated it more... two months later and still no reply... Anyway...at least I got to learn a little about MIDI :-) For the 030 systems, all you do is buy a MIDI adapter for the Mac. I recommend the Optcode MIDI Translator for $45 (Mac Zone). A MIDI adapter is necessary because MIDI is a current loop and your serial port isn't. It consists of a few ICs (most importantly a Sharp PC-900 opto-isolator) and a few resistors; you could make it yourself (the schematic is similar to the one given in "MIDI for Musicians" by C.Aderton) but for $45 (premade), it's not worth it. For the 040 systems (like mine), use the same adapter. But since the 030's use RS422 and the 040's use RS423, you're going to have to modify their cable. The basic difference between RS422 and RS423 is the former is a differential (balanced pair) scheme while the latter still uses a ground. Now the MIDI Translator expects a RS422 (like the Mac uses); you can "convert" the RS422 type device into a RS423 device by grounding the RXD+ and TXD+ lines; albeit crude, it works. The pinout of the MIDI Translator is given below: 1 Clock 2 NC (no connections) 3 RXD- 4 NC 5 TXD- 6 RXD+ 7 NC 8 TXD+ The pinout for the cable that comes with it is: Computer MIDI 1 R Br 2 Br R 3 G O 4 Y Y 5 O G 6 Black Blue 7 P P 8 Blue Black To make the above change, I opened up their cable and shorted the yellow, black and blue wires together. The resultant cable is symmetric. I tested it on my NeXTstation running 2.1, hooked up to a CZ-1. MIDI in (e.g. using the CZ-1 as a controller for Ensemble) will actually work without the above hack, but MIDI out (using the CZ-1 as another 8 voices) won't (unless you do the hack, of course). Notes: 1. The MIDI Translator is self powered (it grabs power off of the line via a capacitor). 2. I make no guarantees to the above. It works for me... 3. I've noticed that Ensemble starts to crap out for complicated midi out's (e.g. skynard32.mid -- see below); this is a bug in Ensemble... 4. For more details on RS422/RS423, see the excellent article "Welcome to the Standards Jungle" in Byte, 2-83. 5. For details on MIDI, check out the midi* files in ucsd.edu. 6. For lots of MIDI files to play, see /music/midi in media-lab.media.mit.edu. Hope this saves someone time getting there NeXT into the music world. Believe me, it's definitely worth it! Enjoy...Ross. -- Please email -- I'll summarize. Ross Cutler University of Maryland, College Park Internet: rgc@wam.umd.edu
crum@alicudi.usc.edu (Gary L. Crum) (05/21/91)
Thanks for posting that info about using MIDI with NeXT computers, Ross. Now, has anyone tried using the MIDI Timepiece by Mark of the Unicorn? I have only seen the box, but it looks good from the feature description -- 8 MIDI inputs, 8 MIDI outputs, and support for advanced features like higher speed and SMPTE timecode. And, it costs around $400 from the "MacUniverse" NeXT reseller here in southern California. (MacUniverse sells Macintosh computers as the name implies, but no salesperson there knew if it would work with the NeXT MIDI device driver.) For the case that someone has used the MIDI Timepiece with a Macintosh, can at least some of its features be used with no special software for the Macintosh, i.e. with the standard Apple MIDI Manager software and applications that use the MIDI Manager? If so, then there is a good possibility that it will work with NeXT computers. I am just not sure if 8 inputs can be handled by the usual MIDI software interface techniques. By the way, Mark of the Unicorn also sells a computer-controlled mixer for line-level analog sound signals. It's called MIDI Mixer 7s, and it has something like 7 pairs of left/right line-level inputs from which it can mix. Oh, and there is a system for combining units nicely (and there is also a system for connecting MIDI Timepiece units). MacUniverse was selling the MIDI Mixer 7s for around $375, I think. I sent a letter to Mark of the Unicorn asking about their products and especially compatibility with NeXT computers, but I haven't yet received a reply. I don't seem them in the latest NeXT software and peripherals catalog so maybe they decided that their products for NeXT weren't working out well (maybe they don't have UNIX expertise). Does anyone have more info? Gary P.S. Mark of the Unicorn's telephone number is (617)576-2760, and their address (which I mailed to) is 222 Third Street; Cambridge, MA 02142.
dat33228@uxa.cso.uiuc.edu (Derek A. Taubert) (05/25/91)
rgc@wam.umd.edu (Ross Garrett Cutler) writes: >To make the above change, I opened up their cable and shorted the yellow, >black and blue wires together. The resultant cable is symmetric. Yuck.. I have one fundamental problem with this: The lines you are shorting to ground are labeled as RTS and CTS on the NeXT side of the connector. It would be in your best interest to cut these lines leading from the computer, to avoid shorting the 10 volts (or whatever it is) that those signals might be producing. This is generally not good for hardware. >I tested it on my NeXTstation running 2.1, hooked up to a CZ-1. MIDI in >(e.g. using the CZ-1 as a controller for Ensemble) will actually work >without the above hack, but MIDI out (using the CZ-1 as another 8 voices) >won't (unless you do the hack, of course). Well, this is most likely due to CTS being low (as it should from the hack) and RTS being high. If a short program existed that could change these signals whenever, you could save yourself the trouble of making a new cable. I'm new to NeXT programming, and I have no idea if you would even be able to modify such things while another process had "control" of the device. ie : device busy problems. Derek -- + Derek Taubert --> derek@mrcnext.cso.uiuc.edu + Author of : GScii+ + + dat33228@uxa.cso.uiuc.edu + and the world's most useless + ++++++++++++++++++++++++++++++++++++++++++++++++ desk accessory -> Amaze me + + There are MOUSE technotes? + *******8-) ++++++++++++++++++++++++++++++++ + Ask me about my GS load meter + ^^^^^^^^^^ Marge Simpson +