Disabling a com port

[e9b9]

If you disable a com port in the BIOS,like com 2.Does it mean it also disables com 4 since they share the same IRQ?

Further,disabling com 2 means you're killing the serial one of your serial ports wired to your motherboard but still can use com 2 if you want with a modem.How does that work?

Thanks.

[NDC]

COM1 and COM2 are your serial ports. Your COM4 port is for your dial up modem. You can go ahead and disable the COM1 or COM2 without effecting the Port for your dial-up modem. Go into the system BIOS and disable the COM Port you want.

[This message has been edited by NDC (edited 01-03-2001).]

[Comtech]

I'm going to elaborate a bit.
Com 1, 2, 3, and 4 are your serial ports.
Com 1 and 2 are commonly found hardwired into the motherboard with connectors to the back for external devices.
Just because Com 2 and 4 (theoretically) have the same IRQ doesn't mean anything, because (aside from stupid Plug-n-Play) you can change the IRQ of any com port.
If you've got a PnP modem, and you want it on com 2 (any IRQ) you must DISable the on board com 2, so the resources are freed up for the modem. This includes memory addressing as well as IRQ.
Except for a Windows environment, two devices may not share resources. Only Windows 95 and up will allow sharing (usually the cause of many headaches) and is still not advised, although most manufacturers seem to put everything on com 10 or 11, just to leave com 1 and 2 available on the system, even if there are no devices attached (external modem or mouse usually).
Disabling com 1 and 2 in BIOS frees up those resources for internal devices such as sound cards, modems, NIC's, etc., and can usually help with devices that "magically" disappear every shutdown, and must continually be reinstalled, stuttering mice, modems that "hang", sound cards that stutter...
Clear as mud?

[storm2k]

i'll make this as simple as i can too. i turned off both my com 1 and 2 ports in my bios (ABit BE6-II mobo/P3-600/Award Bios) and my modem was able to dial out just fine. In addition, seeing as how I dont have any serial devices hooked into my system, I now have a free IRQ (4) where there wasn't one before.

[e9b9]

Gentlemen,

It's as clear as an unmudded lake.Clear as an azure sky of deepest summer.

Thanks,
e9b9