ms0p+@andrew.cmu.edu (Michael Gordon Shapiro) (01/18/90)
I've been having an inordinate amount of trouble getting my Amiga MIDI setup working. Everything used to work fine, until a little while ago when I accidentally plugged my MIDI interface into my powered-up Amiga. There was a bright spark, and following that the MIDI refused to work. Nothing strange so far. Except that my modem still worked perfectly. A friend of mine said that the MIDI protocol uses a subset of what a modem does as far as RS-232 signals go. So theoretically, shouldn't the modem NOT work if there was any damage the the serial port? I swapped my serial and parallel CIA chips, just to see if one had fried. No dice. Same result. The results remained even after using A) Different MIDI interfaces, B) Different MIDI cables, and C) A different synthesizer. All throughout this, the modem still worked perfectly in the same serial port that the MIDI was flouting. The only further clues I have is that every now and then, for no explanable reason, the MIDI will suddenly come to life for a few seconds, registering input on a MIDI monitor program on the Amiga end. Then, invariably, it will freeze up and cease to work thereafter. Does ANYONE technically inclined have an inkling of what my problem is? I'm at the end of my proverbial rope here. Any EMAIL suggestions would be appreciated with fervor.
ammrk@swbatl.UUCP (Mike R. Kraml) (01/18/90)
In article <MZhB9vW00WB704ykVl@andrew.cmu.edu> ms0p+@andrew.cmu.edu (Michael Gordon Shapiro) writes: >I've been having an inordinate amount of trouble getting my Amiga MIDI >setup working. Everything used to work fine, until a little while ago >when I accidentally plugged my MIDI interface into my powered-up >Amiga. There was a bright spark, and following that the MIDI refused >to work. Bummer!!! I can feel for ya, I've done the same. > >Nothing strange so far. Except that my modem still worked perfectly. >A friend of mine said that the MIDI protocol uses a subset of what >a modem does as far as RS-232 signals go. So theoretically, shouldn't >the modem NOT work if there was any damage the the serial port? Correct. MIDI actually uses a current loop interface, by which we opto-couple that to the serial port's pin 2 (data out), and pin 3 (data in), and data and or signal ground. I really can't see how the modem could work and not the midi providing your midi interface is good, cables, etc. I could understand it if MIDI used some of the handshaking lines, (not sure if they are related to the CIAs or not), but MIDI doesn't. > >I swapped my serial and parallel CIA chips, just to see if one had fried. >No dice. Same result. The results remained even after using A) >Different MIDI interfaces, B) Different MIDI cables, and C) A different >synthesizer. All throughout this, the modem still worked perfectly in >the same serial port that the MIDI was flouting. > >The only further clues I have is that every now and then, for no >explanable reason, the MIDI will suddenly come to life for a few seconds, >registering input on a MIDI monitor program on the Amiga end. Then, >invariably, it will freeze up and cease to work thereafter. Almost sounds like a cable problem, but doesn't explain the bright spark either. > >Does ANYONE technically inclined have an inkling of what my problem is? >I'm at the end of my proverbial rope here. Any EMAIL suggestions would be >appreciated with fervor. Sorry, you have done just about everything I would have done. But make darn sure that the substituted MIDI interface, MIDI cables, and MIDI keyboard are working on another system. These things can be a bear. One last thing, MIDI runs at substantially higher baud rates than your 1200 or 2400 baud modem. I am really not sure what Commodore uses for there UART or drivers, but I guess there is a possibility that there is a break down occuring at the higher speeds. Just a possibility, but something the check on as a last resort. Anyway, hang in there, I cooked a Paula before by attaching my joystick sampler while the machine was on, so these things happen, but always remember to turn the power off first before plugging or unplugging any device to your Amiga, they do tend to be fragile. Take care, Mike... ============================================================================= Mike Kraml - Manager-Separations MECHANIZATION - SWBT - (The Techies) UUCP: {uunet, bellcore, texbell}...!swbatl!slims!ammrk =============================================================================
mab@druwy.ATT.COM (Alan Bland) (01/19/90)
In article <MZhB9vW00WB704ykVl@andrew.cmu.edu> ms0p+@andrew.cmu.edu (Michael Gordon Shapiro) writes: >I've been having an inordinate amount of trouble getting my Amiga MIDI >setup working. Everything used to work fine, until a little while ago >when I accidentally plugged my MIDI interface into my powered-up >Amiga. There was a bright spark, and following that the MIDI refused >to work. I did exactly the same thing with my A500 about a year ago, had all the same symptoms, tried everything you did to fix it, and none of it worked. UNTIL one day when I opened up the case, reseated every socketed chip, cleaned out all the dust and cat hair, and generally made sure it looked brand new in there. MIDI started working and has been fine ever since. During that ordeal I bought a new MIDI interface with a switchable serial pass-thru. Anybody want a used Mimetics MIDI interface (no serial pass-thru) for cheap? Good luck. -- -- Alan Bland -- att!druwy!mab == mab@druwy.ATT.COM -- AT&T Bell Laboratories, Denver CO -- (303)538-3510