Abstract: An analog-to-digital converter which is supervised by a microprocessor and includes means for digitally compensating for initial gain and offset errors and gain and offset drift errors due to temperature variations. An analog input voltage is applied to a first analog-to-digital converter, the output of which is both stored in the microprocessor and applied to a linear digital-to-analog converter. The output of the linear converter is summed with the original analog input voltage and the difference applied to the conversion apparatus as an unknown input signal. This process is continued to achieve a desired resolution. The output of a differential temperature sensor is similarly processed to determine the proper amount of compensation for gain and offset drift. The microprocessor provides both control and computation capabilities.