core electronics exam 1

8/8/2019 Core Electronics Exam 1

1/8

Faculty Of Engineering

Department of Electronics & Electrical

Communications

Electronics Core Course Exam 1

Time : 90 minutes

1-Design the full adder circuit.

[Write its truth table and the output equations]

,Then Using 7486 ,7408 and 7432 ;Show the interconnections

required to make the full adder circuit.
http://unimasr.com/community/memberlist.php?mode=viewprofile&u=13555


2/8

2-Design the 8-bit binary adder subtractor circuit using only full

adders and XOR gates. [Draw the complete block diagram]

Then using this hardware show how could the user do the following

operations (show every steps to get the correct result) :

[All the following numbers in this question are in the hex system ]

Adding 54,99 - Subtracting 99 from FB - Subtracting 9A from 3B

Adding FA,AF - Adding 128,57

3-Design the 4-bit binary adder subtractor using only full adders

and (2*1) multiplexers

4-Design and implement the Minority Gate with four inputs.

=>Minority Gate is a combinational circuit which its output equal

Logic One when (less than or equal) half of its inputs equal Logic

One.

(i.e. F=1 if Zero or One or Two of the inputs in the four inputminority Gate equal to One)


3/8

Solution=>First Drawing the truth table showing all possible combinations

The inputs are A,B,C and D [Four Inputs]

And there is only one output.

A B C D F

0 0 0 0 1 )

(

0 0 0 1 1 )

(

0 0 1 0 ..

0 0 1 1 ..

0 1 0 0 ..

0 1 0 1 ..

0 1 1 0 1 )

(


4/8

0 1 1 1 0 )

(

1 0 0 0 ..

1 0 0 1 ..

1 0 1 0 ..

1 0 1 1 ..

1 1 0 0 ..

1 1 0 1 ..

1 1 1 0 ..1 1 1 1 ..

So the Boolean function as a sum of minterms is:

So F=ABCD+ABCD+

Then By Doing All the required Simplifications [Show the steps]

F=ACD+ABC+BCD+AC+CD+BC

So the final design consists of Triple [three-input AND] gates

, Triple [Two-input AND] gates and One [Six Input OR] gate.

As drawn:


5/8

5-In the Alice World, People use the heptal system for the ordinary

calculations [because they have only nine fingers !]

So they use the following numbers : 0,1,2,3,4,5,6,7,8,10,11,.. and

so on.

Design and implement four bit heptal adder using the four bit

binary adder

to help the Alice world people to make their calculations.

6-Prove using Perfect Induction and then using the venn diagrams

the following relationships ;then Covert the LHS from the Product


6/8

of Maxterms to the sum of Minterms then simplify to reach the RHS

:

a)(X+Y)(X+Y)=X

Solution

I-By using Perfect Induction.

(

1 2 3 4 5

X Y (X+Y) (X+Y) (X+Y)(X+Y)

0 0 0 1 0

0 1 1 0 .

1 0 . . .

1 1 . .

Comparing Column (1) and Column (5)

They are identical.

So (X+Y)(X+Y)=X


7/8

II-By using Venns diagram

To convert the LHS (X+Y)(X+Y) from the product of sum to

the sum of product :


8/8

F=(X+Y)(X+Y).

F=(X+Y)(X+Y)

(F)=((X+Y)(X+Y)) By de-morgan

(F)=F=(X+Y) + (X+Y) = XY + XY =X(Y+Y)=X as required.

b) (A+B+C)(A+B+C)(A+B+C)(A+B+C)=A

7-Write a complete C++ program that get from the user two

hexadecimal numbers and output their addition ,subtraction

result using the ordinary C++ operators (+ , - , *, / ) .

Note : You could use any computer programming language

that you know instead.

core electronics exam 1

Documents