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Types of Latches and Flip Flops

    In this section we provide a summary of the operation tables and state transition tables for the common types of latches and flip flops. These tables will be useful for state machine design.

SR  

S	R	Qt+		$Q_t \to Q_{t+}$	S	R
0	0	Qt	hold	$0 \to 0$	0	$\phi$
0	1	0	reset	$0 \to 1$	1	0
1	0	1	set	$1 \to 0$	0	1
1	1	-	invalid	$1 \to 1$	$\phi$	0

D  

D	Qt+		$Q_t \to Q_{t+}$	D
0	0	reset	$0 \to 0$	0
1	1	set	$0 \to 1$	1
			$1 \to 0$	0
			$1 \to 1$	1

T  

T	Qt+		$Q_t \to Q_{t+}$	T
0	Qt	hold	$0 \to 0$	0
1	$\overline{Q}_t$	toggle	$0 \to 1$	1
			$1 \to 0$	1
			$1 \to 1$	0

JK  

J	K	Qt+		$Q_t \to Q_{t+}$	J	K
0	0	Qt	hold	$0 \to 0$	0	$\phi$
0	1	0	reset	$0 \to 1$	1	$\phi$
1	0	1	set	$1 \to 0$	$\phi$	1
1	1	$\overline{Q}_t$	toggle	$1 \to 1$	$\phi$	0

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