Test Papers / Previous Question Papers of IGNOU CS01 Computer Fundamentals June 2005

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

June, 2005

CS01 : Computer Fundamentals

Time: 3 hours
Maximum Marks: 75

1. (a) An 8 bit data 11001010 is transmitted to a distant location. It is received as 11101010. Explain how SEC code would detect this error. (8)

(b) Minimise the following function using the K map.
f(A, B, C, D) = π(0, 1, 4, 5, 10, 11, 16)
Draw the equivalent logic diagram. (5)

(c) Consider the following code : (3)
a=d-e
b=a+f
c=b+d
Make the dataflow graph for the equations above.

(d) Explain the following addressing modes with one example each. Also give one use of each addressing mode. (5)
(i) Register addressing
(ii) Index addressing
(iii) Stack addressing
(iv) Base addressing scheme

(e) Write a program in 8086 assembly language to display a string stored in the data segment on the computer monitor, only if the first character of the string is an uppercase alphabet. (5)

(f) Draw the arithmetic pipeline for floating point subtraction. (4)

2. (a) Find the errors (if any) in the following 8086 assembly language code : (5)
(i) PUSHF AX
(ii) MOV AX, BL
(iii) XCHG MEM_WORD; MEM_WORD2
(iv) ADD BL, CL
(v) lDlV AX, CH

(b) State whether the following statements are true or false. Justify your answers. (3)
(i) Assembly language routines cannot be interfaced with BASIC program.
(ii) The key issue in interfacing is the selection of proper parameter passing.
(iii) Hardware interrupts can be invoked with the help of the INT function.

(c) Draw the logic diagram for 8 x 1 multiplexer. (7)

3. (a) Write a progem in 8086 assembly language to multipiy two 16 bit numbers stored in the data segment into a 32 bit number storcd in the registers. (4)

(b) Make the logic diagram of a 3-bit synchronous counter and explain its operation. (5)

(c) What is the need of a control unit ? What is the basic structure of a control unit ? Explain this with the help of a diagram. Further, give one disadvantage of a hardwired control unit. (6)

4 (a) List two interconnection structures for multiprocessor systems, Explain them with the help of a diagram each. (5)

(b) What is the sequence of the micro-operations that are required for "execute cycle" during execution of a conditional branch instruction ? Make, and state, suitable assumptions. (5)

(c) How does an 8086 microprocessor convert a 16 bit address stored in instructions to a 20 bit address ? Explain this with the help of an example. (3)

(d) What is the need of Direct Memory Access in a computer system ? (2)

5. (a) State whether the following are true or false. Give one reason each in support of your answer. (2)
(i) Vedor processors are most suited for high speed computations. (ii) Memory interleaving is not needed for vector processors as they store instruction and data separately.

(b) Convert the following code to a vector pseudo-code. (3)
for l : = 1 to N
Begin
for J : = 1 to N
Begin
A(i, j) = 50
end
end

(c) What is the need of Cache ? How does it enhance the speed of memory access ? (3)

(d) Give four differences between horizontal and vertical micro-instruction. (4)

(e) Write a program/pseudo-code for execution of the following expression on a zero address instruction. (3)
A = x + y - z * t