Abstract: In a MOS integrated circuit, a voltage level detecting and indicating circuit apparatus is provided. In the apparatus there is provided a MOS integrated circuit means responsive to a change in the magnitude of a voltage in the circuit. In the circuit means there is provided a first node at which occurs a first signal when the magnitude of the voltage is changed to a first predetermined magnitude, said occurrence of said first signal being independent of at least one of a plurality of process variables including threshold voltage, mobility, body effect factor and lateral diffusion within a predetermined range of magnitude of said variable, and a second node at which occurs a second signal when said magnitude of said voltage is changed to a second predetermined magnitude and a third signal when said magnitude of said voltage is changed to the third predetermined magnitude, said occurrence of said second and third signals being dependent on at least one of said plurality of process variables.