英語翻譯
The R-S Flip-Flop.We can realize the latch function with standard logic gates.Fig.4.17 shows a latch constructed from tow NOR gates.The output of each NOR provides one of the inputs for the other NOR.The other inputs are labeled S(for SET) and R(for RESET).The outputs are labeled Q and Q’ because the latch provides complementary outputs.This circuit,called an R-S flip-flop,is similar in its operation to the bistable in Fig.4.16(b).
Let us consider that R and S are both 0 but that Q’ is 1.In this case of the inputs to NOR1 is 1 and hence its output(Q) is 0.This is consistent with the assumption that Q’ is 1,which implies that both inputs to NOR2 are 0.By symmetry,the latch will also be stable with Q=1 and Q’=0.