The PMC66-ADADIO2 is a single-width PMC module which contains eight 16-Bit A/D converters, four 16-bit D/A converters, and all supporting functions necessary for adding flexible analog I/O capability to a PCI host. The board is designed for minimum off-line maintenance, and includes internal monitoring and loopback features that eliminate the need for disconnecting or removing the module from the system for calibration. All analog input and output system connections are made through a single 68-pin subminiature-D front-access I/O connector. The analog outputs can be internally disconnected from the system I/O connector under software control.