Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!usc!elroy.jpl.nasa.gov!cit-vax!tybalt.caltech.edu!sedwards From: sedwards@tybalt.caltech.edu (Stephen A. Edwards) Newsgroups: comp.sys.apple Subject: Re: problems with ProTERM under System Software 5.0 Summary: The dreaded AppleTalk interrupt strikes again Message-ID: <11479@cit-vax.Caltech.Edu> Date: 5 Aug 89 16:25:26 GMT References: <8908040733.aa10223@SMOKE.BRL.MIL> <33749@apple.Apple.COM> Sender: news@cit-vax.Caltech.Edu Reply-To: sedwards@tybalt.caltech.edu (Stephen A. Edwards) Organization: California Institute of Technology Lines: 34 In article <33749@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >In article <8908040733.aa10223@SMOKE.BRL.MIL> V2071A@TEMPLEVM.BITNET ("George A. Piotrowski Jr.") writes: [ The problem with using both a modem and a laserwriter over AppleTalk ] >>is that when slot 7 is set to Appletalk, once I get connected to any BBS >>or the Schools IBM, I get garbage like there is an incredible amount of >>line noise. Once I set slot 7 bact to your card and reboot, Proterm >>works fine. Do any of the Apple people in the System Group have any >>reasons that this is happening??? >On the whole, ProTERM seems rather intolerant of interrupts it didn't enable. >I've seen what you describe when any interrupt sources were running when >ProTERM was launched (heartbeat tasks like text clocks or the debugger init, >AppleTalk, etc.). I guess it's a design flaw. That's one way of putting it. I suspect that it's simply a speed problem. The speed at which AppleTalk interrupts occur is very, very high. According to the IIGS firmware reference (p. 180) "AppleTalk: This interrupt has the highest priority because its code is very time intensive; data can be lost if the SCC is not read within 104.167 microseconds (baud =230,400 ) after an AppleTalk SCC interrupt occurs." When slot seven AppleTalk is enabled, even if you aren't printing to the LaserWriter, these interrupts are occuring, quite effectively bogging down the whole mess. It's not surprising that a few characters are getting lost or garbled. I was in a similar situation, trying to use both the serial port and AppleTalk, and the serial port was dropping characters right and left. This occured both in ProTERM and in AppleWorks GS. Just be glad Apple didn't try to make the poor 65c816 process an Ethernet connection.... Stephen A. Edwards | sedwards@tybalt.caltech.edu