Resetting Windows COM port numbers

One issue I noticed as I played with BlinkyTape on my Windows box was after connecting/disconnecting/opening/closing the tape, I was getting new COM ports and leftover old "ghost" COM ports. Not a serious issue, but annoying. This isn't BlinkyTape's fault, it's an issue with Windows. (Probably has to do with Microsoft working around a dial-up modem driver bug in 1995, but I digress..). I googled up the solution, and figured I'd share it here.

If you're just casually using your BlinkyTape with PatternPaint, etc., you can safely ignore all this. It's mostly for developers who want to avoid tweaking the COM port number in their code. Also, be careful. Un-installing the wrong thing will cause more grief, not less.

First, you need to launch an administrator command shell. Click "Start", type "Command", Right-click on "Command Prompt", and select "Run as Administrator". If it asks to confirm, click yes.

Next, run the following batch script from (or just type into) your admin command shell:

set devmgr_show_nonpresent_devices=1
start devmgmt.msc

- The "Device Manager" control panel should appear.
- Select the "View > Show Hidden Devices" menu.
- Scroll down to "Ports (COM & LPT)" in the list, and double-click it.
- You'll see the inactive "BlinkTape (COMx)" ports with grayed-out icons.
You can right-click on those and select "Un-install".
- Do NOT Un-install the "Blinky Tape bootloader" COM port (it's grayed out too).
- Now select the live BlinkyTape port,
and select "Properties (tab) > Advanced (button) > COM Port Number".
Here you can reset BlinkyTape's COM port number to whatever you want.

These instructions work on my Win7/64 install. I'm not sure if/how things change for Windows 8.


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