The NTE74191 is a synchronous 4-bit binary reversible up/down counter in a 16-Lead plastic DIP type package having the complexity of 58 equivalent gates. Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincident with each other when so instructed by the steering logic. This mode of operation eliminates the output counting spikes normally associated with asynchronous (ripple clock) counters. The outputs of the four master-slave flip-flops are triggered on a low-to-high transition of the clock input if the enable input is low, A high at the enable input inhibits counting. Level changes at the enable input should be made only when the clock input is high. The direction of the count is determined by the level of the down/up input. When low, the counter counts up and when high, it counts down. A false clock may occur if the down/up input changes while the clock is low. A false ripple carry may occur if both the clock and enable are low and the down/up input is high during a load pulse. This counter is fully programmable; that is, the outputs may be preset to either level by placing a low on the load input and entering the desired data at th data inputs. The output will change to agree with the data inputs independently of the level of the clock input. This feature allows the counters to be used as modulo-N dividers by simply modifying the count length with the preset inputs.

The NTE74191 is a synchronous 4-bit binary reversible up/down counter in a 16-Lead plastic DIP type package having the complexity of 58 equivalent gates. Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincident with each other when so instructed by the steering logic. This mode of operation eliminates the output counting spikes normally associated with asynchronous (ripple clock) counters. The outputs of the four master-slave flip-flops are triggered on a low-to-high transition of the clock input if the enable input is low, A high