Star Tech Journal

21
STAR*TECH JOURNAL/JANUARY 1983
_ _ _ _ _ _ I_N_QizITIVE
This month's InQuizltive was sent to us by Ed Zylka/Stem Electronics
33. Find the "Q" output for the following "D" type 74LS74 fliirflop using the given timing
diagram and truth table.
Truth Table
D
D
0*
0*
1
0
Q--
--"CLK
Q
Q
Q
Q
1
0
CLK
1
0
n..
_fl__
Q
Q
a
0
1
*Indicates a don't care condition.
CLK
INPUT
0
I
I
I
D
INPUT
I
0
I
I
I
I
a
INPUT
I
I
I
I
1--
I
I
o _ _J _____ J
Complete the "Q" output timing diagram.
lnQulzltlve Answer (December)
32. Truth Table for "Set-Reset" Flip-Flop
Function
Invalid*
Set
Reset
Latch
s
0
0
1
1
R
0
1
0
1
a
a
*
1
0
*
0
1
a
a
•When in this state, the circuit is not in
a valid flip-flop condition, so this is
disregarded.
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