28 II 2007 1 Intro to Digital Systems

EE 2310 – 001 NAME ______

EXAMINATION T_I

EE 2310 – 001 NAME ______

Draw the logic circuit that takes input of A and B, giving output Y according to the Boolean expression

_ _ _

Y=A.B + A.B + A.B

28 II 2007 1 Intro to Digital Systems

EE 2310 – 001 NAME ______

28 II 2007 1 Intro to Digital Systems

EE 2310 – 001 NAME ______

Here is a circuit diagram. Give the equivalent Boolean expression in SoP form (input A, B, and C; output Q)

28 II 2007 1 Intro to Digital Systems

EE 2310 – 001 NAME ______

Very few devices are available with positive edge triggering, but that doesn’t matter. It is very easy to change a negative edged circuit to use the positive edge if we need to. Think for a while and figure out what one could change in a clocked circuit so that it would behave so that transitions would occur on the positive edge of the pulse from the clock and so like a positive edged triggered circuit. (One slight change in the total circuit is all that’s needed!)

Honor Code: I have neither received nor given help on this examination

Here is the logic table for a circuit with inputs A, B, C, and D; output Y:

ABCDYDraw the Karnaugh map, simplify and give

00001a simple Boolean expression for the result.

00010

00101

00110

01000

01011

01100

01111

10001

10010

10101

10110

11000

11011

11100

11111

On page 174 of Tokheim there is a full-adder pulse-train problem (8.13). Suppose that on input pulse (a), Cin is zero as before. Now change the problem for all the other input pulses by connecting Cout to Cin so the carry-in is the previous carry-out. Now what are the sum outputs?

Pulse a =pulse b =pulse c =pulse d =

Pulse e =pulse f =pulse g =pulse h =

P.S., Can you give some meaning to this result?

28 II 2007 1 Intro to Digital Systems

EE 2310 – 001 NAME ______

6. Suppose we are given the Boolean expression

_ _

A . B + B . C = Y

with inputs A, B, and C; output Y. If we find our supplies only include 7432IC’s (4-two input or’s) and 7404IC’s (6-nots or inverters), we will have to use some Boolean Algebra to convert that expression into one involving only OR’s and NOT’s [Hint: DeMorgan’s Laws and Double Negation are all you need]. Convert it and then draw the circuit for your result.

7. Here is a Karnaugh map with some “Don’t Cares” in it (‘x’) for output f. Simplify it in the usual way and show the resultant Boolean expression and circuit.

8. Here is a circuit taking inputs of A and B with output Q. Give the logic (truth) table for it. Can you describe the effect of this circuit with one simple Boolean expression? Finally, wire the 7400IC shown so as to realize that circuit. (Lines will cross each other so make it clear which are actually connected)

28 II 2007 1 Intro to Digital Systems

EE 2310 – 001 NAME ______

[End of Test]

28 II 2007 1 Intro to Digital Systems