Quatech RS-232 PCI serial boards utilize a single PCI slot to provide 2, 4, or 8 independent asynchronous serial ports that share a single interrupt. All PCI registers are properly implemented, so you can be assured that Quatech boards will be good citizens on the PCI bus.
The RS-422/485 serial boards are available with either 2 or 4-ports. The ports are jumper configurable for either RS-422 or RS-485 in any combination for full and half duplex networks. PCI registers are properly implemented to assure that Plug-and-Play works reliably, and that the board will not cause PCI bus conflicts.