·
Show all your
steps—answers alone are not sufficient.
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Homework must be
done neatly
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Use
straight-edged paper (no notebook tear-outs with ragged edges)
·
STAPLE papers to
a signed cover sheet.
Please print the following for reference and for this
assignment: MUX-Decoder instructions. Also, please print for reference and
inclusion in your Homework paper MSI diagrams 74LS151
(8-to-1 MUX) and 74LS138 (3-to 8 Decoder/De-MUX)
1.
Use a 74x151
(8-to-1 MUX) to implement f(W, X, Y, Z) = Sm(2, 4, 7, 8, 9, 13,
14). Use the “row-pairs”
method shown in class. Show all enable
and address connections. (20pts) (See instructions above.)
2.
Use a 74x138
decoder and an external AND gate to implement f(X, Y, Z) = Sm(1, 2, 4, 5, 6). Show all
enable and address connections. (HINT:
AND the MAX terms) (20pts) (See instructions above)
3.
Use a 74x138
decoder and an external NAND gate to implement f(p, q, r) = Sm(1, 3, 7). Show all enable and
address connections. (20 pts) (See instructions above)
4.
Design an 8-to-1
MUX from three 4-to-1 MUXs. Label
the inputs on each 4-to1 MUX as I0 to I3.
In the “first stage,” place one MUX on “top” of another
and connect their select lines S1 (most significant) and S0 together. Let I0 on the “top” MUX correspond
to D0 of 8 inputs and let I0 on the “bottom” MUX be D4. Use the third MUX to select between the two “first-stage” MUX
outputs. You can configure a 4-to-1 MUX
to be a 2-to-1 MUX by setting its MS select line to logic “0.” When you finish, label the three 8-to-1 select
lines as S2 (most significant) to S0 (least significant). (20 pts)
5.
Design an 8-input
to 8-output MUX-DEMUX system using a 74x151 for the MUX part and a 74x138 for
the DEMUX. Leave the outputs of the
74x138 as active-low signals (leave
the output bubbles as-is). Configure (“hard
wire”) the select-lines values on the MUX and address-lines values on the
DEMUX so that input D4 is routed to output Y6_L. Wire so that there is only one active low ENABLE signal that
controls both chips. You can do this because there are 3 enable
lines (one active high, two active low) on the DECODER (20pts).