Monday, December 10, 2007

Hughes placement paper

1. given a digital ckt with nand
gates. what is o/p
Ans. nor gate
2. given an logical
expr. x,y,z. simplify
ans. xz
3. It is recommended to use which type of variables in a recursive
Ans. static variables.
4. which one of following is not memory management model?
given buddy system, monitors, paging, swapping
Ans. monitors
5. what m/c is used to recognize context free grammar ?
Ans. pushdown automata
6. Which type of grammar can be recognized by finite state m/c Ans.
right linear
7. proc() {
static i=10;
If this proc() is called second time, what is the o/p
Ans. 11
8. int arr[] = {1,2,3,4}
int *ptr=arr;
*(arr+3) = *++ptr + *ptr++;
Final contents of arr[]
Ans. {1,2,3,4}
9. TCP/IP hdr checksum : what method is used ?
Ans. one's complement of sum of one's complement.
10. CSMA/Cd is used in which lan
Ans. ethernet
11. 8085 pgm : LXI sp, 2021,
LXI b, 1234 (??)
push b
contents of stack after pushing ?
12. One question on synchronous transmission :
ans. Timing info is embedded in data itself
13. What for start bit is used in RS232 transmission.
14. One solution for
deadlock prevention for dining philosopher's problem
Ans. Allow one person to take first left stick and then right stick
and remaining persons in reverse order.
15. 4bit seq no in sliding window protocol with selective repeat.
what is the max no. of acks that can be held at transmitter
ans. 8
16. given a height balanced tree. If we add one more node , how
many nodes gets unbalanced ?
Ans. 3
17. Given a arbitrary pointer to an element in a singly linked list?
what is the time complexity for its deletion .
Ans. O(n)
18. what is the diff b/n c and c++
a. dynamic scoping
b. nested switching
c. declaration of variables in any code block
d. separation of compilation and linking
Ans. c (??)
19. which one is false ?
a. 0s*s; s->a
how many parse trees possible : a+a*a+a
Ans. 5
21. 4-1 demultiplexer is to be implemented using a memory chip.
how many address lines and word length required
Ans. 4, 1
22. Vector intr mechanism. in 8085.
Ans. fixed locations in memory when an intr comes.
23. ARP is used for : Ans. IP to MAC addr conversion.
24. given 100 to 999 nos. Probability of picking a no. with out
digit 7.
Ans. 18/25.
25. Ten film rolls. 3 defective, prob. of picking up 2 defective
rolls with out replacement
Ans. 6/90
26. The purpose of hashing is :
Ans. O(1) complexity
27. Given adjacency matrix for a directed graph with n vertices
and e edges. How much time will it take to find out indegree
of a vertex
Ans. O(n)
28. No. of nodes of degree 2 in a binary tree with n leaf nodes.
Ans. n-1

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