The AX99100 PCIe to High Speed Serial Port driver is software that allows Windows to communicate with the AX99100 chip, which is a PCI Express (PCIe)-based chip used to add high-speed serial ports (RS-232/RS-422/RS-485) to a computer. This chip is often used in industrial, embedded, or specialized applications where additional serial ports are required for communication with external devices such as sensors, modems, or serial communication equipment.