On 28 Jan 99, at 0:08, Chris Blom wrote:

> Hi experts,

> I have a digital camera that needs a 9-pin serial port connection to
> the computer.  My desktop has its mouse connected to the only 9-pin
> serial port it owns.  I tried connecting to the 24-pin serial port
> via an adaptor, but that did not work -- the system did not seem to
> recognize its existence.
>
> (I use COM1 for the mouse and COM4 for my modem.)

  It appears that the 25-pin connector is probably attached to COM2,
which (a) may be disabled in your CMOS setup, and (b) might not be
acceptable to the camera software.  [Yes, people still write some
programs that only work with COM1.... Grrr.]

> My question; can one add another 9-pin serial port via an expansion
> card?  And if so, how do you assign a COM port to it?

  COM port numbers are usually assigned by the BIOS at startup, when
it finds enabled hardware at any of the standard serial port device
addresses.

> Second question; is there any way to change over to a PS style mouse
> to free the 9-pin serial port for use by the camera?

  This is really easy if your motherboard already provides a PS/2 mouse
connector.  If not, you need to find a card that provides the port, and
it will tie up a slot.


  What I would do in this case is:

(a) Enable COM2 via the CMOS setup.  Some BIOSes will just give you an
Enabled/Disabled setting, others may offer a menu of addresses and IRQs.
Standard settings are:

  COM1   3F8   IRQ 4
  COM2   2F8   IRQ 3
  COM3   3E8   IRQ 4
  COM4   2E8   IRQ 3

(b) Move the (serial) mouse from COM1 to COM2.  Depending on the
choices your CMOS offers, this could be done in software configuration,
or by using your adaptor to plug the mouse into the 25-pin connector.
[It's also possible to swap the connectors' ribbon cables inside the
machine, but that's more work.]

(c) Move the modem from COM4 to COM3.

(d) The remaining connector should now be active as COM1, and work with
your camera.

NOTE:  This has COM1 (camera) and COM3 (modem) both using IRQ 4.  This
means that you cannot use both at the same time -- don't try to run the
camera software while you're online, and vice-versa.



David G

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