Abstract: A tester system tests the transfer characteristics and operability of an analog to digital converter (ADC) embedded in a microprocessor. The tester generates a sequence of analog signal test values, and prompts the microprocessor to read and convert each test value. The microprocessor sets up a table in its internal memory, the table having one tally value for every possible code output by the embedded ADC. After the embedded ADC converts each test value, the microprocessor reads the digital value output by the embedded ADC and increments a corresponding tally value in its internally stored table. When the sequence of tests is completed, the microprocessor transmits the entire table of tally values to the tester. The tester then performs a well known set of calculations on the tally data to determine the transfer characteristics and operability of the embedded ADC.