ECE 3441 Fall 2025
Quiz 4
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Closed book, closed notes
No cheat sheet is allowed.
Only four function calculators are allowed.
Show all details of your work to obtain credit (The answer alone will not suffice).
You may not talk during the quiz to others or to yourself.
You have 50 minutes.
Please do not open the booklet unless instructed
to do so, or a substantial penalty will result.
First Name Last Name,
Question
1
2
3
Total
Peoplesoft ID,
Points
Date DD/MM/YYYY
Maximum
35
30
35
100
Total: _______/100 possible points + 10 bonus points
A sequential circuit has the form shown in Figure 1.
Figure 1: Sequential Circuit
a) Is this a Mealy Machine or Moore Machine?
b) Derive the next state and output equations.
c) Construct a transition table
d) Construct a state graph.
depends
9) mealy machine , since the output
on
ヤ
t
b Q1
+
=
J1Q- + 4ia1a2
=
+
&
=
X*
Z
=
52a'
+
kiQ
↓
↓
田
十
。
Question #1(35 Marks):
e
+
Xx2' *1
や Qと t
t=
*2
XQz' + X *a *z
x *1' + XQc *2
'
=
10
Z
I1 O
-
* Q:
=
Q2 xB2' + xP1a
1그 I
10
1그
㉕
X
언
①⑫임
+=
←
8
㉕
∞
ㅇ
스
O언
□
X
①⑫임
\
_
ㅁ
\
_
스
∞
ㅇ
그
언
=8
1그
∞
그
^
10
그
10
ㅇ
τ
X
①1임
_
언
\
1
=
언
ㅇ
1
그
스
10
그
∞
田
十
9) Q1+
□
스
」
十
十
QI+ a2t
앤⑫
Present
z
Net
O
1
=
=0
output
⑧
*อ
건
언
ㅇ
∞
ㅢ
OO
0인
앤⑫
Present
Q 1+
X
0
언
어
그란
OO
10
a2t
E
output
Net
ヤ =0
ャ =1
ㄻ
X
So
%
So
Sz
10
s1
σ인
그
53
언
S2
so
仕
어
SI
1o
o
5o
0
Sz
□ ll
)
a
ol >
Sy
S
‰
I∅
So
-
기
I1 그
∅
㎡
^
80
I
<
11 그
^
Question #2 (30 Marks):
A sequential circuit has one input X, one output Z, and three flipflops Q1 Q2 and Q3. The
transition and output tables for the circuit follow:
Present
State
000
001
010
011
100
101
110
111
X=0
100
100
000
000
111
110
011
011
Next State
X=1
101
101
000
000
110
110
010
011
Output (Z)
X=1
0
1
0
1
0
1
0
1
X=0
1
0
1
0
1
0
1
0
b) E A. II
-
a) Construct a timing chart for the input sequence X=0101 and intital state Q1Q2Q3=000.
Identify any false outputs. (Assume that the flipflops are rising edge trigerred and that the
input changes midway between the rising and falling edges of the clock.
b) List the output values produced by the input sequence.
CLK
_
1
X
스
Q⑫
丄
0
ㅇ
ㅇ
스
스
ㅇ
ㅇ
0
ㅇ
1
스
⑬
ㅇ
_
∅
1
요
ㄴ
ㅇ
ㅇ
ㅇ
ㄶ
□
ㅣ
z
↑
False
b)
E = 10 ]1
.
Question #3 (35 Marks):
Design a Mealy machine that detects the following sequence: 1101. Any sequence ending in
1101 will result in an output Z=1 (all other times it will be a zero). The detector does not reset
when a 1 output occurs. (Hint: 4 states are required)
State
"
Below is a sample input (X) and output (Z):
X
1
1
0
1
1
0
1
0
0
1
1
0
1
1
Z
1
0
0
0
0
0
1
0
0
0
0
1
output
0
0
Sy
SI
1
ㅦ
I1
㎥
tO
⑰
↴
%
1
Sz
7
∞
%
S1
급
? )1o
do
<
Sz
θ
ㄻ
JK FLIP-FLOP
A Mealy machine is a finite-state machine whose output values are determined both by
its current state and the current inputs.
A Moore machine is a finite-state machine whose output values are determined only by
its current state.
Example Mealy machine state graph and state tables: