The 74LS161 Synchronous 4-Bit Binary Counter has an internal carry look-ahead for use in high-speed counting designs. All flip-flops are clocked simultaneously to provide synchronized operation, allowing the outputs to change simultaneously when directed to do so by the count-enable inputs and internal gating.

This mode of operation eliminates the output counting spikes that are typically associated with asynchronous (ripple clock) counters. The four flip-flops on the rising edge are triggered by a buffered clock input (positive-going).