Analog output system compatible with digital system bus

An analog output system coupled to a digital system bus (1, FIG. 1) comprises a RAM (8) in which digital data may be input from the system bus. The data is converted into analog form by digital-to-analog converters (30-37) in either continuous mode or intermittent mode, depending upon the contents of control/status register (18). The system also comprises interrupt logic (6), bus arbitration control logic (16), and reconstruction filters (40-47). A watchdog timer (50) zeroes all outputs which have not been accessed via the system bus (1) within a specified time period. The conversion rate can be controlled either by an internal timer (52) or by an external trigger (57). The output channel configuration and conversion frequency are fully software programmable.