3. If the master’s J and K inputs are both high, it toggles on the PT of the clock and the slave then toggles on to clock NT. Regardless of what the master does, therefore, the slave copies it; if the master sets, the slave sets; if the master resets, the slave resets.
4. If J = K = 0, the flip-flop is disabled and Q remains unchanged.
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Fig. 8-26
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Fig. 8-27 Master-slave flip-flop.
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Fig. 8-28 7476 JK master flip-flop.
The symbol for a 7476 master-slave flip-flop is shown in Fig. 8-28. Either it can be preset to Q = H by talking PR low, or it can be reset to Q = L by talking CLR low. These two inputs take precedence over all other signals!
There is something different however. First of all, notice that the clock (C) is not edge-triggered. The master does in fact change state when C goes high. However, while the clock is high, any change in J or K will immediately affect the master flip-flop. In other words, the master is transparent while the clock is high, and thus J and K must be static during this time. The truth table in Fig. 8-28b reveals this action by means of the pulse symbol ( )