View Full Version : COM ports

02-01-2003, 02:09 PM
I have an IBM thinkpad 760 at work I use for diagnostics. It is running win 95 and some diagnostic software by Mars Electronics Intl. (Proprietary crap.)

Anyway, some jackass apparently thought it would be funny to disable my serial port (COM 1) in hardware profiles. After re-enabling the com port, I had to restart. When the machine re-booted, the COM port was no longer COM 1 but COM 4. All of the aforementioned crappy diagnostic software I use looks for the hardware interface at COM 1 and cannot be set for COM 4, and therefore cannot interface with the hardware.

So my question now becomes, how do I, in win 95, change a COM 4 port into a COM 1 port?

02-01-2003, 02:32 PM
Unbeleivable someone has to be an Ass even if they were just joking...

Only thing i know is that You can't change com1 into com2,
but you can change the resources used by the first com port so that it
will be recognised by something looking for a port where com1 is
usually to be found.
Com1, 2, 3, 4 are labels for the humans, the computer doesn't care
what their name is, most of the time.I know that coms share IRQs (IRQ 3 is Coms 2 & 4, IRQ 4 is COMS 1 and that two devices can share these Com pairs as long as they aren't functioning simultaneously?

I'm not really sure how to fix this sorry I'm sure someone does I'll do some playing around though.. I just don't have a functioning W/95 unit

02-01-2003, 02:55 PM
You could try removing the port in hardware profiles, rebooting and entering the bios, disable both com ports, save and exit, and reboot. Let it go through to windows, and then shut down, after checking that the comm ports don't exist.
Then reboot, go back to bios, and enable the com ports, save and exit, reboot.
When you re-enter windows, you should find that the ports are back as they should be.

david eaton
02-01-2003, 03:08 PM
Yawningdog. It looks as if the port address and IRQ have been changed. To reset them, try looking in Control Panel<>system<>device manager, and delete both COM ports. Probably best to work this in safe mode. Reboot and see if the computer redetects them with the default settings.


02-02-2003, 10:06 PM
I alredy tried deleting the com port from hardware profile, and then re-booting, but the OS always detects the port and assignes it to COM 4 again.

The bios is hard to get at (there's no prompt when I boot) and changing resources sounds iffy. IRQ's, DMA channels and I/O addresses are easy enough to change I guess, but the next person who gets this machine (if I ever leave that job:mad: ) may run into some trouble and not knowing the changes I made will be a huge mess.

02-02-2003, 11:39 PM
Do you have a Winmodem set up? I seems they like to grab COM1. I wonder if you might want to Device Manager>Remove the modem and see what happens on a reboot?? Just a thought....

Well, perhaps enter SETUP and reassign the Serial Ports to other COM ports or disable...and then REBOOT

02-03-2003, 06:22 PM
Sounds like a good call Whyzman. I suspected that some other device might be sucking up the resources normally used for COM1. In fact, there is a PC card modem installed which is not used, so I'll try that tomorrow.

I did figure out how to change the port to COM3. In device manager-properties, I can uncheck the "use default" box and select other configs, but none of them amounts to COM1. For some weird reson, win95 wont let me just set irq channel and I/O address manually. Resource conflicts, I suspect.

02-03-2003, 06:50 PM
IBM site regarding the 760
760 (http://www.pc.ibm.com/support/cgi-bin/essearch?lang=en_US&brand=IBM+ThinkPad&family=&machineType=&doctype=&subtype=All)
bios (http://www.pc.ibm.com/support/cgi-bin/essearch?lang=en_US&&doctype=&subtype=All&brand=IBM+ThinkPad)

I think the bios is F1 on the thinkpad judging by this

a guess (http://www.pc.ibm.com/qtechinfo/PFAN-3PZSYN.html?lang=en_US&doctype=&subtype=All&brand=IBM+ThinkPad)

press and hold F1 while the system boots.
If that doesn't enter bios, then do the same with ESCAPE