Problems have been reported on operation of serial ports
on Mac PowerBooks in the past, especially in connection with
MIDI.  It may be that your problem is related to that!
I am referring here to earlier PowerBooks, not G3s. 

FAIW. 

Best

Iannis Zannos
SIM
Tiergartenstr. 1, 
D-10785 Berlin, Germany
Fax: +49 30 25481172

----------
>From: Mark Guzdial <guzdial at cc.gatech.edu>
>To: squeak at cs.uiuc.edu
>Subject: Re: Mac Serial Ports on PowerBooks
>Date: Fri, 26 Feb 1999 6:27 PM
>

>At 5:05 PM -0800 2/25/99, Maloney wrote:
>>It sounds like something else is using the serial port.
>>The most obvious candidate is AppleTalk, if you have it configured
>>to use LocalTalk. But it could also be OMS or the MIDI manager or
>>a terminal enumlator.
>>
>>You could try (a) turning off AppleTalk and (b) booting with
>>extensions off.
>
>Just to report: I just tried turning off EVERY EXTENSION (including Fax --
>thanks, Pat for the suggestion!) except CFM-68K.  Same error -- primitive
>failure.  I also tried a variant on Joshua's suggestion -- I hardcoded the
>selection of the portnumber to be a "1" and a "2", rather than the default
>"0".  Same thing.
>
>Curious.
>
>Mark
>
>--------------------------
>Mark Guzdial : Georgia Tech : College of Computing : Atlanta, GA 30332-0280
>(404) 894-5618 : Fax (404) 894-0673 : guzdial at cc.gatech.edu
>http://www.cc.gatech.edu/gvu/people/Faculty/Mark.Guzdial.html
>
>
>