Data type Range Default value
REG_DWORD 0 | 1 0


Determines whether serial ports can be set to the same interrupt request level (IRQ). Some ports do not work properly if two ports have the same IRQ.

Value Meaning
0 Each serial port on the computer must have a different IRQ.
1 Serial ports on the computer can have the same IRQ.

Note Image Note

The value of this entry is used as the default value for all serial ports on the computer. Settings for specific serial ports are stored in the device-specific subkey for that port in the Enum subkey (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum).

Tip Image Tip

To change this value, you must edit the registry. To change the PermitShare setting for a specific serial port, use Device Manager.