Note: Question one is compulsory. Answer any three from the rest. All algorithms should be nearer to C-programming language notation.

1. Design a context free grammar for the following :

(i) Switch statement in C-language.

(ii) An arithmetic expression in C-language.

(iii) Write a shell program to calculate the following :
· Greatest Common Divisor (GCD) for the two given numbers
· Generate Fibonacci numbers

(iv) Discuss whether there are any advantages of using a multitasking operating system, as opposed to a serial processing one, in a computer system dedicated to serving the needs of a single user. Explain the tradeoffs involved and describe some representative applications that support your arguments.

(v) What is the difference between internal and external fragmentation?

2. (i) Discuss the development environments of GUIs.

(ii) What is the basic philosophy of X-Windows? How is it different from the rest of the GUIs?

3. (i) What is a semaphore mechanism? How do you define semaphore operations? Take three processes and explain a run time behavior of three processes controlled through a semaphore.

(ii) Write mutual exclusion algorithm using semaphore. What are the drawbacks of semaphore?

4. (i) Answer the following with reference to Unix operating system:
· How does diff compare with comm in comparing unsorted files?
· Find all lines with exactly 15 characters in them.
· Write a regular expression to express C-language variables.
· List of commands used as filters.
· What happens if you try to copy a file to itself, that is, give the same name to the target as to the source thus

% cp file 1 file 1

(ii) List the important features of Unix O.S.

5. (i) Differentiate between the following :
· Spooling and Buffering
· Network operating system and Distributed operating system
· Preemptive scheduling and Non-preemptive scheduling
(ii) Discuss the three common file organization techniques.

6. (i) Discuss the following with reference to segmentation :

(a) Address mapping in a segmented system
(b) Sharing and protection in a segmented system

(ii) Scan disk scheduling with one example.