Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!wuarchive!texbell!texsun!newstop!sun!stpeter!cmcmanis
From: cmcmanis@stpeter.Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga
Subject: Re: DMCS & MIDI guru problem
Keywords: help!
Message-ID: <132463@sun.Eng.Sun.COM>
Date: 2 Mar 90 23:34:22 GMT
References: <1828@esunix.UUCP>
Sender: news@sun.Eng.Sun.COM
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Organization: Sun Microsystems, Mountain View
Lines: 39

In article <1828@esunix.UUCP> blgardne@esunix.UUCP (Blaine Gardner) writes:
>He's running Deluxe Music Construction Set with a FB-01 (?) through a
>MIDI interface. Whenever he exits the program, the machine crashes. This
>only happens when he has been using the MIDI interface. Just using the
>Amiga's stereo output causes no problems.

FB-01 == Yamaha FB-01 FM Tone Generator

I believe the following to be true :

The Amiga serial.device has a bug in it that it doesn't disable 
serial interrupts when it is closing down and about to get rid of
the interrupt handler it had created. 

I know this to be true :

Yamaha MIDI equipment sends a constant stream (one every .5 sec or so) of
"I'm Alive" MIDI messages. (It's part of the spec but no one except Yamaha
seems to do it)

This is conjecture :

When the serial.device is closing, and it gets a character, the interrupt
vectors through a now bogus interrupt handler and boom! down goes the Amiga.
I haven't tried the 1.3.2 serial device yet so I don't know how well it
works. Another way of getting this behaviour is to have a Yamaha device
connected to a MIDI interface while the system is booting. Guru time when
the I'm Alive message comes in. 

Workaround :

Disconnect the MIDI device (via a rotary switch box) before opening or
closing the serial device. 


--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@Eng.Sun.COM
These opinions are my own and no one elses, but you knew that didn't you.
"If it didn't have bones in it, it wouldn't be crunchy now would it?!"