On  1 Jun 98 at 20:17, Angus Ching wrote:

> My colleague has an internal modem detected at Com 3. Is there any
> way to make any changes (hardware or software) so that Windows
> detects the modem at Com2 or any other Com ports??

  COM1/2/3 refers to which slot in the "BIOS Data Area" contains
information about this port.  Luckily, the BIOS searches for COM
ports to fill in this area in a well-defined sequence, and so odds
are very good that each "slot" will contain common "base address"
values:

COM1  3F8
COM2  2F8
COM3  3E8
COM4  2E8

  So part of changing which COM port the modem shows up as involves
changing its base address, and disabling -- or changing the address
of -- any device already at the address where you want the modem to
go.
  Odds are good that COM1 and COM2 are being provided by your
motherboard, and can be enabled/disabled, or possibly reassigned,
through your CMOS setup.


  What's wrong with putting the modem on COM3?  My guess would be
that you probably have your mouse on COM1, and when you try to use
the modem, it wants to use the same IRQ (4) as the mouse is already
using.
  There are three basic solutions to this:

1.  Reassign the modem to use IRQ 5 or IRQ 7, or some other free IRQ.
You'll have to tell the OS you've done this -- how will depend on
what OS you use.  In theory, PnP should be helpful here, but I find I
actually get better results from modems that offer a bunch of
different jumper settings.

2.  Disable COM2 in the CMOS setup, and configure the modem for
address 2E8 and IRQ 3.  Many home users will fine two COM ports is
sufficient.

3.  Move the mouse to COM2.  Generally, serial mice have 9-pin
connectors and COM1 provides a 9-pin connector -- but often COM2 is
a 25-pin connector.  25-to-9 connectors are a standard item (as are
9-to-25; check that the pins go the right way!), or you can swap the
cables which connect the ports to the motherboard.  [On an ATX
motherboard, you can't swap them -- but since they're both 9-pin, it
doesn't really matter.]
  Note that this gives you a "free" port, which you can use for other
purposes, as long as you don't try to use it while connected via
modem.  That might or might not be useful.

David G