Abstract: A measurement and control system including a digital computer, a digital to analog converter for providing an analog data signal from digital data from the computer, a command sample and hold for holding the data analog signal as a control command signal, a measure sample and hold for holding an analog input signal indicative of a preselected variable, a measure comparator for comparing a series of analog outputs of the digital to analog with the held analog input and providing the comparison to the computer which calculates a measurement of the variable as a function of the comparisons. The output of the command sample and hold may be the system output or a command comparator may compare the output of the command sample and hold and the analog input to provide a system output signal.