CSE2300W
Homework 4
1. (10 points) Assuming 74HCT283’s are used, find the critical path of the circuit in
Figure 689 (on page 482). What’s the delay on the critical path? Table 63 on page 367
lists the propagation delay of many chips, including 74HCT283. The implementation of
74x283 is shown in Figure 687 on page 480.
2. (20 points) Show how to build each of the following single or multiple output logic
functions using one or more 74x138 or 74x139 binary decoders and NAND gates. (Hint:
Look at the implementation of a decoder and think about how it is related to minterms.)
a) F =
Σ
A,B,C
(1, 3, 4, 5, 7)
b) F =
Σ
A,B,C,D
(0, 2, 8, 12, 14)
c) F =
Σ
A,B,C,D
(2, 3, 4, 5, 8, 10, 12, 14)
d) F =
Σ
A,B,C
(0, 2, 4, 5)
and G =
Σ
A,B,C
(1, 2, 4, 6)
3. (5 points) Implement F = X
′
•
Z + X
•
Y with the following types of threestate buffer
and a pullup resistor (if you think it is necessary). Use no more than four threestate
buffers.
4. (10 points) Suppose that you are asked to design a new component, a decimal decoder
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 Fall '08
 SHI
 Critical path, 4bit, 16bit, five 4bit, multiple output logic

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