> ><<I believe the problem is an overlap in IRQ addresses. Doesn't COM3 use > >the same address as COM1and Com4 as Com2 (normally)?>> > > > >Yes; the "standard" settings are > > COM1: 0x3F8, IRQ4 > > COM2: 0x2F8, IRQ3 > > COM3: 0x3E8, IRQ4 > > COM4: 0x2E8, IRQ3 > > > >Since the PC/AT architecture uses edge-triggered interrupt lines, it is > >not possible to share an IRQ line between two devices. > > > >However, it is at least as likely that he is having a problem with his > >I/O address; for unknown reasons, IBM used an I/O address range that > >includes 0x2E8 when they designed the 8514/A video adapter. Since there > >are a lot of video adapters that support this interface, including such > >popular items as almost all ATI adapters and all current S3 chips, there > >are a ton of video adapters out there that won't work with a COM4 device, > >even if the user selects an unused IRQ line. Yuk. > > > >Steve Dirickson WestWin Consulting > >(360) 598-6111 [log in to unmask] > I had the same problem on my PC when I configured my modem on COM4. I called > Microsoft Tech support and diagnosed that I had a case of "sliding IRQ"! What > the net of all this is: You cannot have your modem configured on COM4 if you > do not have a physical COM3 device configured - do you have a COM3 device? If > not try setting your modem to COM3 and see if that works. > > Dennis > Please forgive me - I don't want to start a holy war, but I can't resist: Get a Mac! ;-) Ken Wolff "It's hard to work in a group Database Administrator when you're omnipotent" Lockheed Martin - "Q" (Star Trek TNG) Denver, Colorado If my employer thinks my opinions are of no consequence, why should you?