S-R Flip-Flop
- A set-reset flip-flop can be constructed from cross-coupled NOR gates.
- The set and reset inputs of the cross-couples NOR flip-flop are high active.
- A set input will force the Q output high and the output low.
- A reset input will force the Q output low and the output high.
- With neither the set input nor the reset input active, the flip-flop is in a "hold" condition and will "remember" the last input condition.
- A S-R flip-flop can also be made using cross-coupled NAND gates.
- The cross-coupled NAND flip-flop has low active set and reset inputs. These can be made high active by using inverters.
- A flip-flop is "latched" when the Q output hold the last input condition.
- A flip-flop is said to be transparent when the Q output responds immediately to a change on the input.
- A register is a group of flip-flops used to store a binary word. One flip-flop is needed for each bit in the data word.
- AND gates can be used to "strobe" or enable data gated into a register.
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