Sample WDM Modem Drivers
The Serial.sys driver is an example of a WDM driver that is used to support COM port modems on Windows 2000 and later versions of the operating system. Serial.sys is a function driver for legacy COM ports and Plug and Play COM ports. Serial.sys is also a lower-level device filter driver for Plug and Play devices that require a 16550 UART-compatible interface, but which are not attached to a COM port.
For more information about the operation of the serial.sys driver, see Serial Devices and Drivers and Serial Driver Reference.
You can also find information about the serial.sys driver from the following sources:
Data definitions in the #include file \inc\api\ntddser.h in the Windows Driver Kit (WDK).
Sample code in the Serial driver sample.
Microsoft Win32 Communications API.
There is also a FakeModem.sys WDM driver sample that is included in the VirtualSerial driver sample.