Buses and ports: New in the WDK for Windows 8.1
Windows 8.1 includes version 2 of the serial framework extension (SerCx2). SerCx2 is a system-supplied component that supports serial communication between integrated circuits (ICs) on a printed circuit board. This extension simplifies the development of custom drivers for serial controllers (or UARTs) on System on a Chip (SoC) ICs. For more information, see Using Version 2 of the Serial Framework Extension (SerCx2).