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Asked: 2026-05-18T02:51:21+00:00

I am using Windows XP and some serial ports. I had never had any

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I am using Windows XP and some serial ports. I had never had any problem with this serial ports, however now I am experiencing a very strange issue: when I open the Hyperterminal, I see two COM1s and two COM3s.
Searching for the solution, I have found that in the registry, in the folder \HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM there are the regular COMs, with name \Device\Serial0 and value COM1 or any other COM and two other variables with name COM1 and COM3, and values COM1 and COM3 also.
When I try to erase or rename them, they go back to their original values when I restart the computer.

I don’t know what to do, but I need to use the COMs. And while this problem isn’t solved, the COM1 and COM3 are not working.

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1 Answer

  1. Editorial Team

    In the registry set the REG_SZ value HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\DEVMGR_SHOW_NONPRESENT_DEVICES to 1 and then look in the device manager if you can see the COM ports.

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