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NATIONAL OPEN UNIVERSITY OF NIGERIA
UNIVERSITY VILLAGE, PLOT 91, CASDASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI, ABUJA.
FACULTY OF SCIENCES
JANUARY/FEBRUARY 2018 EXAMINATION
CIT344 – Introduction to Computer Design Credit Units: 3
Instruction: Answer Question (1) (22 marks) and any other four questions each carrying 12 marks
Time: 2½ hours
1a) Write short notes on Combinational logic circuit enumerating how it is analysed and designed. (Total = 10 marks)
- Give a full-adder function table and its corresponding implementation. (6 marks )
(c) State the two basic operations performed on memories and the signals typically used to support them. (6 marks )
2a) Differentiate between a multiplexer and a demultiplexer. (6 marks )
(b) Provide suitable diagrams in support of your answer in (a) above. (Total = 3 marks)
(c) Why do we need to expand memory? (3 marks)
3a) Discuss the typical applications of encoders and decoders. (7 marks)
(b) Using diagram only, show how interrupts are resolved with 2-to-4 priority encoders. (5 marks)
4a) Compare and contrast sequential and combinational logic circuits. (6 marks)
(b) Convert the binary number 1101001 to (i) Octal and (ii) Hexadecimal (3 marks)
(c) Convert the binary number 101011001 to (i) Octal and (ii) Hexadecimal (3 marks)
5a) Give the block diagram of a sequential circuit.
(b) Draw the diagrams of a NAND-based S-R latch and a NOR-based S-R latch. (3 marks)
(c) Compare the operations of your diagrams in (b) above. (6 marks)
6a) Discuss, very briefly but succinctly, the operating characteristics of a flip-flop. (10 marks)
(b) What are the two major categories of memory chips? (2 marks)
7a) State the two major functions of a register and its different shift operations. (7 marks)
(b) State the defining characteristics of finite state machines. (5 marks)
