The XR17D1581 (D158) is an octal PCI Bus Universal Asynchronous Receiver and Transmitter (UART) with support for PCI Bus universal VIO buffers in the same package and pin-out as the XR17C158, XR17C154 and XR17D154. The device is designed to meet the 32-bit PCI Bus and high bandwidth requirement in communication systems. A global interrupt source register provides a complete interrupt status indication for all 8 channels to speed up interrupt parsing. Each UART has its own 16C550 compatible set of configuration registers, transmit and receive FIFOs of 64 bytes, fully programmable transmit and receive FIFO level trigger levels, transmit and receive FIFO level counters, automatic RTS/CTS or DTR/DSR hardware flow control with programmable hysteresis levels, automatic software (Xon/Xoff) flow control, IrDA (Infrared Data Association) encoder/decoder, 8 multi-purpose inputs/outputs and a 16-bit general purpose timer/ counter.