This tester utilizes the classic four-wire measurement technique to ensure highly accurate resistance measurements, especially for low resistances. The main components of its measurement circuitry include a programmable constant current source, a programmable preamplifier, and an A/D converter. The central control unit directs the constant current source to supply a stable and precise current to the external load under test. Subsequently, it processes the collected data, such as test voltage and current, to determine the actual resistance value.