# Answer the question / digital logic

No.1

Using the 3-variable multiplexer chip of figure 3.12 (pp. 161 in the textbook 1, 6/e), 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.

No.2

The 3-variable multiplexer chip, shown in figure 3-12 (pp. 161 in the textbook 1, 6/e), is actually

capable of computing an arbitrary function of Jour Boolean variables. Describe how, and as an

example, draw the logic diagram for the function that is 0 if the English word for the truth table

row has an even number of letters and 1 if it has an odd number of letters.

No.3

Draw the logic diagram of a 2-bit demultiplexer, a circuit whose single input line is steered to

one of the four output lines depending on the state of the two control lines.

No.4

Draw the logic diagram of a 2-bit encoder, a circuit with four input lines, exactly one of which is

high at any instant, and two output lines whose 2-bit binary value tells which input is high.

No.5

A common chip is a 4-bit adder. Four of these chips can be hooked up to form a 16-bit adder.

How many pins would you expect the 4-bit adder chip to have? Why?