Test Papers / Previous Question Papers of Indira Gandhi National Open University CS01 Computer Fundamentals June 2006

PGDCA / MCA (I Yr) / BCA
Term-End Examination

CS01 (S): Computer Fundamentals

Time: 3 hours
Maximum Marks: 75

June 2006

1. (a) Simplify the following expression using Karnaugh's map in product-of-sum form. F (A, B, C, D) - ∑ (0, 2, 8, 9, 10, 11, 14, 15) Also, draw the logic circuit for the simplified exnression.

(b) What is a vector instruction? Explain briefly the need of an array processor in the execution of a vector instruciion. 5

(c) Construct an 8 x 1 multiplexer, using two 4 x 1 multiplexers and a decoder. Make assumptions, it required.

(d) What is cache coherence? Why is it important for shared-memorym ulti-processor systems? (4)

(e) Write an 8086 adsembly laflguage program to find the total number of occurrences of the characters "a" and "t" in an array of characterss tored in the memory. (5)

(f) Explain, with an example, one instruction of each of the following types : (6)

(i) Conversion

(ii) Input-output

(iii) Transfer of control

(iv) Arithmetic

2. (a) Write a program to evaluate the following expression using an evaluation-stack architecture machine : A x B / D + E x F - G Assume that the machine contains instructions for PUSH, POP, ADD, SUBTRACT, MULTIPLY and DIVIDE (6)

(b) Construct a full-adder circuit using one or more decoders. (5)

(c) What is the set-associative mapping scheme for memory? Explain this with the help of a diagram. 4

3. Give at least three differences between each of the following : (15)

(i) Instruction pipeline vs' Floating point pipeline'

(ii) Horizontal microinstruction vs' Vertical microinstruction.

(iii) Access methods of secondary storage vs' Access methods of main memory.

(iv) Loosely coupled microprocessors vs ' Tighily coupled microprocessors.

(v) Flash memories vs. PROMs.

4. (a) Design a single precision floating point number having the following characteristics:
The base of the number is 2'
The mantissa can represent at least 5 decimal digits correctly.
The exponent range is 10^{&plusminus; 50} Make suitable assumptions if required (5)

(b) Write a program in 8086 assembly language that adds two two-digit unpacked BCD numbers (5)

(c) What is the purpose of data-flow machines? List at least two advantages and two disadvantages of these machines. (5)

5. (a) Explain the role of the segment registers in 8086 microprocessors, with the help of an example for each. (6)

(b) What are the basic characteristics of RISC? Explain briefly the reasons that make RISC based designs more popular. (4)

(c) An 8-bit register contains the binarv value 11001011. Perform the following opnrufion, on this :

(i) Mask the upper nibble of the register. (A nibble is a 4-bit sequence.)
(ii) Insert a value 1101 at the upper nibble.
(iii) Perform circular shift right.
(iv) Perform arithmetic shift left.
(v) Perform logical shift right.
Make assumptions if required. (5)