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

BACHELOR IN COMPUTER APPLICATIONS
Term-End Examination

December, 2005

CS64 (S) : INTRODUCTION TO COMPUTER ORGANISATION

Time: 3 hours
Maximum Marks: 75

1. (a) Using 2's complement notation perform the following arithmetic operations using 8 bit register(s) : (5)
(i) 25 + (-12)
(ii) 17 - 6
(iii) -18 - 16
(iv) -8 + (18)
(v) 12-(-19)

(b) Design a combinational circuit that accepts a 4 bit binary number and generates an output binary digit equal to 1 if the input number has even number of 0's. Otherwise the output is 0. (7)

(c) Explain the use of 'IDIV' and 'AAS' instructions, with the help of an example of each. (6)

(d) Write a program for evaluating A x B/C + D/E - F using 2 address and 3 address machine instructions. Make suitable assumptions, if any. (6)

(e) How does the CALL instruction improve the 8086 programming methodology ? Explain two differences between FAR and NEAR procedure calls in 8086 micro-processor with the help of a suitable example for each case. (6)

2. (a) Consider a traffic light at a cross-road A, B, C and D (as given in following figure) having corresponding delays for the stop signal as 20, 10, 5, 5 seconds, respectively. Write a program in 8086 assembly language for implementing it. Make, and state, suitable assumptions, if any. (7)
-----DIAGRAM-----

(b) Explain different steps of an instruction cycle for multi-operand instructions, with the help of an example. (6)

(c) If a memory read cycle takes 50 ns and a cache read cycle takes 10 ns, then (using this data) can you prove that the performance with cache is better ? Make suitable assumptions about hit ratio. (2)

3. (a) What is the need of many addressing modes in a machine ? Give four addressing modes that must be Present in a machine. Justify your selection. (5)

(b) What is an interrupt ? Why do they occur ? What is IVT in 8086 micro-processor ? How is it useful in interrupt processing ? Explain this with the help of an example. (8)

(c) How is the access time defined for the hard disks? (2)

4. (a) Draw selector and multiplexer I/O channels. Also explain in which situations each would be applied. (4)

(b) Represent the following numbers using IEEE 32-bit floating point format :
(i) 0 (ii) 4.62 x 10^-11 (iii) 6.52 x 10⁹

(c) An 8 bit input word 01010110 on transmission is received as 01001011. How can the SEC code be used to rectify the error in the received data ? (6)

5. (a) Explain the following terms with the help of a suitable diagram/example each : (9)
(i) I/O processor
(ii) Logic micro-operations
(iii) Micro-instructions

(b) What is bus arbitration ? Explain the Daisy chaining and Polling bus arbitration methods with the help of a suitable diagram for each. (6)