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NATIONAL OPEN UNIVERSITY OF NIGERIA
UNIVERSITY VILLAGE, PLOT 91, CASDASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI, ABUJA.
FACULTY OF SCIENCES
APRIL 2019 EXAMINATION
COURSE CODE: CIT344
COURSE TITLE: Introduction to Computer Design
CREDIT: 3 Units
TIME ALLOWED: 2½ Hours
INSTRUCTION: Answer Question 1 and any other FOUR (4) Questions
1a) Briefly explain the Repeated Division-by-2 method. (4 marks)
b) Convert 111010110101110010110 in binary to Octal (2 marks)
c) State the advantages of assembly language over high level languages. (4 marks)
d) Compare the ASCII code and the Extended ASCII code (3 marks)
e) Briefly explain the term combinational logic circuit. (2½ marks)
f) Complete the Logic Function Generator based on 3-Variable Logic Function Table below: (2 marks)
|
Input |
Output |
||
|
A |
B |
C |
Y |
|
0 |
0 |
0 |
|
|
0 |
0 |
1 |
|
|
0 |
1 |
0 |
|
|
0 |
1 |
1 |
|
|
1 |
0 |
0 |
|
|
1 |
0 |
1 |
|
|
1 |
1 |
0 |
|
|
1 |
1 |
1 |
|
g) State the following the Sum and the Carry-out Boolean expressions for a Full-Adder. (3 marks)
h) List the three different types of edge-triggered flip-flops generally used in digital logic circuits. (1½ marks)
2a) Briefly explain how a combinational logic circuit can be analysed and designed. (6 marks)
b) What is a DeMUX? (2 marks)
c) List two (2) forms of DeMUX. (2 marks)
d) What is a Gray code? (2 marks)
3a) What do you understand by the term ‘decoder’? (2 marks)
b) Give the truth table and logic symbol of a 2-to-4 Decoder. (3 marks)
c) Distinguish between Jumps and Loops (2 marks)
d) List the five ways of modeling the behaviour of finite state machines (5 marks)
4a) Enumerate any four different forms of Call instructions. (4 marks)
b) State the functions of the far call instruction (4 marks)
c) Briefly describe a sequencer, giving at least one example of a sequencer. (2 marks)
d) Write short notes on Read and Write Signals. (2 marks)
5a) State the functions of the near call instruction (3 marks)
b) State the function of an edge-detector? How does it perform this function? (2 marks)
c) Describe the Displacement-only addressing mode (5 marks)
d) State four uses of Edge-Triggered J-K Flip-Flops. (2 marks)
6a) State the two basic operations performed on memories and the signals typically used to support them. (6 marks)
b) State the two major functions of a register. (2 marks)
c) Outline four of the different forms of shift operations of a register. (4 marks)
