The M54/74HC4518/4520 are high speed CMOS DUAL 4 BIT BINARY COUNTERS fabricated in sili2 con gate C MOS technology. They have the same high speed performance of LSTTL combined with true CMOS low power consumption. They consists of two identical internally synchronous 4-stage counters. The counter stages are D-type flip-flops having interchangeable Clock and ENABLE inputs for incrementing on either the positive-going or negative-going transition. For single-unit operation the ENABLE input is maintained "high" and the counter advances on each positive-going transition of the CLOCK. The counters are cleared by high levels on their clear lines. The counter can be cascaded in the ripple mode by connecting Q4 to the enable input of the subsequent counter while the clock input of the latter is held permanently low.