COM port

using Arduino Uno, operating system is Windows XP.

The Windows system assigns the Arduino Uno to Port 9 (device manager). But under the menu Tools>port the choice of Port 9 is not offered - only port 1, 2, 4 and 8. Any suggestions how I can circumvent this problem?

Poorman:
operating system is Windows XP.

Get out of the stone age. What version of Arduino? XP hasn't been supported for quite some time. It's time to upgrade. If you don't want to spend the money then get Linux (Ubuntu is nice and easy for Windows folks to learn). It's free and it works better than Windows.

I thought the issue that kept the IDE from working on XP had been fixed (after something made it manifest on more recent versions, and it suddenly became a problem)... While XP is an old OS, I'm doubtful of whether this is actually an OS problem.

Does one of the options in the tools -> port menu go away when you unplug the arduino and appear when you plug it in? If so, that's the one to use.

DrAzzy:
I thought the issue that kept the IDE from working on XP had been fixed (after something made it manifest on more recent versions, and it suddenly became a problem)... While XP is an old OS, I'm doubtful of whether this is actually an OS problem.

I didn't know they'd fixed it. But I wouldn't be surprised if it caused more. It's not even supported by Windows anymore. It's almost 16 years old now. A lot has changed in the world in the last 16 years.