GATE: Starts and stops Timer / Counter by means of a signal provided to the pin $ \bar{INT} / \bar{INT}0$

M1 - Timer / Counter operates only if the bit $ \bar{INT} / \bar{INT}0$ is set

M0 - Timer / Counter operates regardless of the state of the bit $ \bar{INT} / \bar{INT}0$

C/$\bar{T}$ : Timer of Counter selector cleared for timer operation (input from internal system clock) . Set for counter operations (input from $T_x$ input pin)

M1,M0: These two bits selects the Timer operating modes.