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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!news.unimelb.EDU.AU!munnari.OZ.AU!spool.mu.edu!sgigate.sgi.com!news-res.gsl.net!news.gsl.net!nntp.coast.net!zombie.ncsc.mil!news.mathworks.com!newsfeed.internetmci.com!hunter.premier.net!netnews.worldnet.att.net!ix.netcom.com!netcom.net.uk!dispatch.news.demon.net!demon!awfulhak.demon.co.uk!awfulhak.demon.co.uk!awfulhak.demon.co.uk!not-for-mail From: brian@awfulhak.demon.co.uk (Brian Somers) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Modem at COM3: can't find it! Date: 25 Jun 1996 23:31:11 -0500 Organization: Coverform Ltd. Lines: 31 Message-ID: <4qqeef$cj@anorak.coverform.lan> References: <4q4bho$7ht@netnews.upenn.edu> <4q6227$qc0@panix.com> <31CE3919.4A982BB@lambert.org> NNTP-Posting-Host: localhost.coverform.lan X-NNTP-Posting-Host: awfulhak.demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Terry Lambert (terry@lambert.org) wrote: : J Wunsch wrote: : ] Not that i really like to defend M$, but that's rather the fault of : ] Little Blue's geniusses of engineers. They've been to stingy to use a : ] tri-state gate for driving the IRQ line, which would have allowed for : ] shared interrupts, but yet assigned the default IRQs for com1/com3 and : ] com2/com4 twice. : Actually, there is no IBM standard for com3/com4. This was done : by a modem manufacturer who needed to plug his internal modems : into a machine with two onboard serial ports with no way to : disable the ports in hardware. : I even know which one. Thankfully, the manufacturer is dead, : and will remain blameless (and me lawsuitless). Are you sure ? I thought IBM made an "ask the BIOS" standard. I havn't got the book handy for the next couple of weeks - I can't even remember the name of the book, but I'm sure one of the crappy COM bios DOS interrupts is responsible for at least specifying the available com i/o addresses. I can't recall if it also specified their IRQs. Of course (if the above is correct - it's been a while since I read that chapter) there weren't actually any available IRQs on the single PIC PC/XT model, so their "BIOS support" would have become defunct as soon as the BIOS was first copied. Maybe the guys who first reverse-engineered the BIOS didn't even appreciate that there was an intention for a COM3/COM4. -- Brian <brian@awfulhak.demon.co.uk> Don't _EVER_ lose your sense of humour....