Homework 5

Due Sept. 22

  1. There exist four Boolean functions of a single variable and 16 functions of two variables. How many functions of three variables are there? Of n variables?

  2. Show how the AND function can be constructed from two NAND gates. (Use Logisim)

  3. Using the three-variable multiplexer chip of Fig. 3-12, implement a function whose output is the parity of the inputs, that is, the output is 1 if and only if an even number of inputs are 1. (You may want to test with Ligisim)
    Figure 3-12

  4. If all the gates in Fig. 3-18 have a propagation delay of 1 nsec, and all other delays can be ignored, what is the earliest time a circuit using this design can be sure of having a valid output bit?

  5. Sometimes it is useful for an 8-bit ALU such as Fig. 3-19 to generate the constant −1 as output. Give two different ways this can be done. For each way, specify the values of the six control signals. (The six inputs are: A, B, ENA, ENB, INVA, CarryIn).

Figure 3-18



Topic revision: r2 - 2014-09-17 - JimSkon
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