|Data type||Range||Default value|
|REG_DWORD||1 - 16||14|
Determines how many characters are sent at a time to the transmit FIFO buffer of a National Semiconductor 16550-compatible device.
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).
To change this value, you must edit the registry. To change the TxFIFO setting for a specific serial port, use Device Manager.