SR LATCH
SR Latch SR latch is also called as Set Reset Latch. This Latch effects the output as long as the Enable E is maintained at 1. The circuit has two inputs S and R. The circuit has two outputs Q(t) and Q'(t). The upper NOR Gate has two inputs R and the complement of the present state, Q(t)' and produces the next state Q(t+1) when Enable E is 1. Similarly the lower NOR Gate has two inputs S and present state Q(t) and produces the complement of the next state Q(t+1)' when Enable E is 1. We know that a two-input NOR Gate produces an output, which is the complement of the other output when one of the input is 0. Similarly produces 0 output, when one of the input is 1. When S is 1, the next state Q(t+1) has the value 1, irrespective of present state, Q(t) values. When R is 1, the next state Q(t+1) has the value 0, irrespective of present state, Q(t) values. At any time, both inputs cannot have the value 1, otherwise the value Q(t+1) is not defined. Table of SR-Latch: