DM74S161 Datasheet, National Semiconductor

Y Synchronously programmable Y Internal look-ahead for fast counting Y Carry output for n-bit cascading Y Synchronous counting Y Load control line Y Diode-clamped inputs .

without additional gating Instrumental in accomplishing this function are two count-enable inputs and a ripple carry out.

These synchronous presettable counters feature an internal carry look-ahead for application in high-speed counting designs They are 4-bit binary counters The carry output is decoded by means of a NOR gate thus preventing spikes during the normal coun.