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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!nntp.coast.net!howland.erols.net!news.mathworks.com!uunet!in3.uu.net!206.58.0.35!news.structured.net!nntp.teleport.com!nntp0.teleport.com!tlw From: tlw@teleport.com (Tommy Willoughby) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Serial ports and internal modems.. Date: 28 Nov 1996 18:02:48 GMT Organization: Teleport - Portland's Public Access (503) 220-1016 Lines: 36 Message-ID: <57kk48$86e@nadine.teleport.com> References: <57f6f9$ffh@bambam.soi.city.ac.uk> NNTP-Posting-Host: kelly.teleport.com X-Newsreader: TIN [version 1.2 PL2] Alan Messer (adm2@sarc.city.ac.uk) wrote: : Hiya, : My machine comes with 2 serial ports as one would expect sitting on the : usual IO addresses and interrupts (3 & 4).. Just recently I've brought an : internal modem for the machine which has a config to make the modem act as : either COM1-4. no problem I thinks and I configured the port to COM4 for the : internal modem.. My understanding of this is that it uses a slightly : different IO address to COM2, but the same interrupt.. Before placing this : on my machine I tried it with no problems under my brother's Win95 machine.. : No problems.. : Now I've come to configure my FreeBSD (2.1.0) box to use the modem.. I : placed a sio line in the config for COM4 and the same interrupt and : recompiled the kernel.. But the new port isn't recognised.. COM3 neither. : On reading the FAQ/Handbook in closer detail it reveals that serial : ports can't use the same interrupt.. Yet, under DOS this would seen to : be the norm.. So what gives? The internal modem has no config to move the : interrupt (well that's not quite true there are 6 or 7 dips but with no : more documentation than 4 settings for the different COM combinations).. : And my BIOS/motherboard don't allow the interrupts to be changed.. ... The book "The Complete FreeBSD" from Walnut Creek CDROM explains this pretty well. The short answer is MSDOS doesn't use the interrupt. UN*X, being more intimate with the hardware can give much better performance, but can also be tougher to set up in some cases. I disabled my motherboard's COM1 in CMOS setup, then plugged the modem in. This works great for me, & still leaves one "hot" external serial port for use. With a PS/2 mouse using it's own port, one sio is plenty for me. -- tlw@teleport.com