Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!zephyr.ens.tek.com!tektronix!gvgpsa!gvgpvd!andyp
From: andyp@gvgpvd.GVG.TEK.COM (Andy Peterman)
Newsgroups: comp.sys.mac
Subject: Re: Bad Serial Port
Message-ID: <1458@gvgpvd.GVG.TEK.COM>
Date: 7 Jan 90 02:43:17 GMT
References: <5923@eos.UUCP>
Reply-To: andyp@gvgpvd.GVG.TEK.COM (Andy Peterman)
Distribution: comp
Organization: Grass Valley Group, Inc.; PVD
Lines: 32

In article <5923@eos.UUCP> dencisco@eos.UUCP (David Paul Encisco) writes:
>I wouldn't be concerned if this was the first serial port that blew on my
>Mac IIx, but unfortunately this is my forth blown serial port in two monthes
>on a year old machine. I practice safe Mac: never unplug anything while the
>machine is on. I've also checked for power surges and found no problems and
>we connected my micom line to another Mac and it works great!
>
>The message I get when using Versaterm:"Sorry the communications port is in
>use by another program. You may continue off-line or try to use the
>communications port anyway." This is in fact false, I'm not using another
>program nor can I use the port anyway. MicroPhone has a more definitive error
>message: "OS Error -28 occurred at point 500", which at least informs me that
>the I/O driver is not open.
>
>Has anyone else had similar problems with the serial port?

I don't think you've "blown" your serial port.  It sounds like a problem
with the Chooser.  Have you been running a MIDI program recently?
If so, this problem can show up.  (Especially with Apple's MIDI
Manager!).

To fix it, find one of these MIDI programs, start it up and then quit
it, and finally open and close the Chooser.  This is the only way to get
the port working again!!  I first came upon this problem after loaning
my Mac to a friend who was using it for some MIDI work.  When I got it
back, the serial port was hung up and I spent hours trying to fix it.  I
was able to hack into the System code and get it reset, but I cannot
remember what it was I did.   The method above is suggested by Apple in
their documentation on the MIDI Manager.  Its a known bug with the
Chooser.

	Andy Peterman