The M54/74HC190/191 are high speed CMOS 4-BIT SYNCHRONOUS UP/DOWN COUNTERS fabricated in silicon gate C2MOS technology. They have the same high speed performance of LSTTL combined with true CMOS low power consumption. State changes of the counter are synchronous with the LOW-to-HIGH transition of the Clock Pulse input. An asynchronous parallel load input overrides counting and loads the data present on the DATA inputs into the flip-flops, which makes it possible to use the circuits as programmable counters. A countenable input serves as the carry/borrow input in multi-stage counters. Control input, Down/Up, determines whether a circuit counts up or down. A MAX/MIN output and a Ripple Clock output provide overflow/underflow indication and make possible a variety of methods for generating carry/borrow signals in multistage counter applications. All inputs are equipped with protection circuits against static discharge and transient excess voltage. October 1992