The PCI-COM422/4 is a four-port, asynchronous serial communications card designed for use in PCI-Bus computers. It supports RS-422 communications. The card is 6.1 inches (155 mm) long and may be installed in any 5-volt PCI slot in IBM and compatible computers. Type 16550 UARTs are used as the asynchronous communication elements. These include a 16-byte transmit/receive FIFO buffer to protect against lost data in multitasking systems while maintaining 100 percent compatibility with the original IBM serial port. A crystal oscillator is located on the card and permits precise baud rate capability up to 115,200. Higher baud rates, up to 460,800 baud, are achieved by changing a jumper on the card. The driver/receivers used, type 75176, are capable of driving extremely long communication lines at high baud rates. They can drive up to ±60 mA on balanced lines and receive inputs as low as 200 mV differential signal superimposed on common mode noise of +12V to -7V. In case of communication conflict, the driver/receivers feature thermal shutdown. When the card is first installed, Windows will detect it as new hardware and assign it an IRQ number and base address. There are no switches to set or base addresses to assign, making it easy to use. From this point on, the card behaves as standard COM ports at COM 5,6,7, and 8. You cannot set or change the card's base address, you can only determine what the system has assigned. The PCI Bus supports 64K of I/O address space so your card's address may be located anywhere in the 0000 to FFFF range.