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Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!haven.umd.edu!umd5.umd.edu!roissy.umd.edu!mark From: mark@roissy.umd.edu (Mark Sienkiewicz) Newsgroups: comp.os.386bsd.questions Subject: Re: Modem setup on 386BSD [and a further QUESTION] Date: 28 May 1993 21:28:04 GMT Organization: University of Maryland Lines: 50 Message-ID: <1u6054$o6l@umd5.umd.edu> References: <1993May27.043819.13711@mcshub.dcss.mcmaster.ca> <CJB.93May28115334@thrip.cs.uq.oz.au> <1993May28.195017.23712@fcom.cc.utah.edu> NNTP-Posting-Host: roissy.umd.edu In article <1993May28.195017.23712@fcom.cc.utah.edu> terry@cs.weber.edu (A Wizard of Earth C) writes: >In article <CJB.93May28115334@thrip.cs.uq.oz.au> cjb@cs.uq.oz.au (Christopher J Biggs) writes: cjb>Question: Has anyone got a driver that will drive a multi-IO card at IRQ 2&3 cjb>and an internal modem on 2or3 (it wont go anywhere else!!). terry>I haven't seen one yet -- and, unless you have a very special modem and com terry>card, you aren't going to be able to write one -- ever. ... terry>boards, on the other hand, *do* support flagging the interrupt source, terry>*but* require a driver that knows about the flagging mechanism. Some terry>UARTS (but not the low-end ones in most PCs) support a status register terry>indicating "data in FIFO". This can be used the same way as a hardware I'd be very interested in knowing what UARTS you are referring to, since I've never heard of such a beast. The 16450, 16550, and 8251 all have a bit that indicates "received data ready". It is the least significant bit of one of the status registers (the one at byte 5, so for COM1 it is at 3F8+5 = 3FD). You could easily poll all your UARTS to find incoming data. (I use this technique to do some serial communication on Ms. Dos.) cjb>Question: Has anyone got a driver that will drive a multi-IO card at IRQ 2&3 cjb>and an internal modem on 2or3 (it wont go anywhere else!!). The internal PC modems that I've seen all look just like plain serial ports to the computer. That makes this problem the same as having three serial ports. The hard problem is this: If you set two boards to interrupt on the same IRQ, they fight each other. One board tries to pull the pin high and the other tries to pull it low. Often enough, you just don't see the interrupt, but sometimes you burn up the chip driving that pin. Are you sure your multi-IO card can only be IRQ 2 or 3? Most of the ones I've seen let you use 2 or 3 for COM2 and 3 or 4 for COM1. This would get you the 3 interrupts you need. Alternately, you could kludge the board so that both interrupts are gated onto the same pin. Then you can hack the device driver to check more than one chip on interrupts. So... No, I don't have one, but in principle, a little hardware hacking and a little software hacking and you could have one yourself. Mark S.