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EE 101 Homework 5
Redekopp
Name: ___Solutions______________________________
Due:
Score: ________
Show work to get full credit.
Remember, use on only one side of the paper and staple them together.
Only use a calculator to CHECK your work, not to DO your work.
1)
(36 pts.) Design (create one schematic drawing for) each of the following single or
multiple output logic functions using the building blocks listed below for each
problem along with a NAND gate for each output bit.
a.
F
1
=
∑
WXYZ
(0,3,6,7,10,12,14)
(20 pts.)
F
0
=
∑
WXYZ
(1,4,7,13,15)
Using (2) 3to8 decoders each w/ activelow outputs and 2 enables: 1 active high
enable (G1) and 1 activelow (/G2).
Besides the 3to8 decoders and the NAND
gates to implement each output bit, you should not need any additional gates.
In general, an ninput function can be built with an nto2
n
decoder.
Thus we need a 4to
16 decoder.
So first build a 4to16 decoder, then use it to OR together minterms.
Since
the outputs are active low, NAND together minterms.
/Y0
/Y1
/Y2
/Y3
/Y4
/Y5
/Y6
/Y7
A0
A1
A2
3to8
Decoder
G1
/G2
/Y0
/Y1
/Y2
/Y3
/Y4
/Y5
/Y6
/Y7
/G2
/O0
/O1
/O2
/O3
/O4
/O5
/O6
/O7
/O8
/O9
/O10
/O11
/O12
/O13
/O14
/O15
W
W
0
1
X
Y
Z
X
Y
Z
F0
F1
Equivalent to 7input NAND
(We can’t draw a 7input NAND
w/ drawing program).
Same is true for F1.
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b.
G =
Π
ABCD
(1,2,5,6,7,9,10,13,14,15)
(16 pts.)
Using (5) 2to4 decoder each w/ (1) activelow enable and activelow outputs
A
B
/D0
/D1
/D2
/D3
/E
A
B
/D0
/D1
/D2
/D3
/E
A
B
/D0
/D1
/D2
/D3
/E
A
B
/D0
/D1
/D2
/D3
/E
A
B (MSB)
/D0
/D1
/D2
/D3
/E
A
B
0
D
C
D
C
D
C
D
C
/O0
/O1
/O2
/O3
/O4
/O5
/O6
/O7
/O8
/O9
/O10
/O11
/O12
/O13
/O14
/O15
G
Equivalent to 6input
NAND (We can’t
draw a 6input NAND
w/ drawing program)
3
2)
(8 pts.) Examine the decoder on the attached page:
Label the enable with E or /E
depending on whether it is active high or low.
You must figure out which output
corresponds to which gate based on the gate connections.
Then label the outputs
appropriately using Y
0
Y
1
Y
2
Y
3
or /Y
0
/Y
1
/Y
2
/Y
3
depending on whether they are
active high or low.
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This note was uploaded on 06/23/2008 for the course EE 101 taught by Professor Redekopp during the Fall '06 term at USC.
 Fall '06
 Redekopp

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