Test Papers / Previous Question Papers of IGNOU CS64 Introduction to Computer Organisation December 2005

BACHELOR IN COMPUTER APPLICATIONS
Term-End Examination

December, 2005

CS64 : INTRODUCTION TO COMPUTER ORGANISATION

Time: 3 hours
Maximum Marks: 75

1. (a) Convert the octal number 577.46 to the following : (6)
(i) BCD equivalent
(ii) Decimal number
(iii) Binary number
(iv) Hexadecimal number

(b) Simplify the following boolean function using Sum-of-Product form, by Karnaugh's map : (6)
F(A, B, C, D) = Σ (0, 2, 3,5, 7, 8, 10, 13, 15)

(c) Design a combinational circuit that accepts a 3 bit binary number and generates an output binary number equal to 1 if the sum of input numbers are equal to '10' in binary, otherwise the output is 0. (6)

(d) Write an instruction sequence for evaluating A + B x C + D / E x F using zero address instructions and one address instructions. (4)

(e) Write a program in 8086 assembly language to generate the first five terms of the Fibonacci sequence. Also draw an appropriate flow chart for your program. (8)

2. (a) Explain the main memory to-cache mapping using a set associative scheme, with the help of an example. (6)

(b) Explain the use of 'AAA' and 'DAA' instructions, with the help of an example of each. (4)

(c) Consider the following piece of code which has been written in some high level language, and wite the equivalent code in assembly language. (5)

index = 0;
while((index>15) && (string1[index]
== string2[index]))
index ++;

3. (a) "Counter is a register." Justify this statement. Draw and explain the working principles of a 4 bit ripple counter. (6)

(b) In some situation, multiple interrupts occur at the same time. Explain how one can deal with these multiple interrupts. Give any two approaches. (4)

(c) The 8 bit registers AR, BR, CR and DR, initially have the following values :
AR = 10110110
BR = 10010101
CR = 11100101
DR = 00111010

Determine the 8 bit values in each register after the execution of the following sequence of micro operations : (5)
(i) AR ← AB ^ BR
(ii) BR ← CR ⊕ DR
(iii) DR ← DR - CR
(iv) CR ← AR x DR where '^' denotes AND and '⊕' denotes XOR.

4. (a) Assume that your marks of 12th class are stored in a memory array. Write a program in 8086 assembly language to find out the percentage of marks. If any student has scored marks more than "75" in any subject, s/he should be awarded distinction in that subject. Make suitable assumptions. (5)

(b) Using four (4 x 1) multiplexers and four full adders, construct a 4 bit arithmetic circuit, With the help of suitable tables, explain how this circult can peform different arithmetical operations. (6)

(c) Draw any two DMA configurations and explain the advantages and disadvantages of these configurations. (4)

5. (a) Define access time and cycle time. Is cycle time equal to access time ? Give reasons for your answer. (4)

(b) Draw a circuit diagram of an 8 x 8 RAM. (3)

(c) Explain the 2½ -D chip organisation. How does it differ from the 2D chip organisation? (4)

(d) Explain four differences between horizontal and vertical micro instruction formats. (4)