STMicroelectronics Placement Papers and Sample Papers

Following papers are for year 2004,2005,2006,2007. Click Here for placement papers 2008,2009,2010.

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Aptitude - General

ST MICROELECTRONICS PAPER ON 15TH NOVEMBER 2007

PART- A
a.9*1 Apti Questions
b.Virtual memory is greater than physical memory
c.Cycle stealing is related to DMA?
d.Conditional operation are stored in flag seg?
e.Some question on stack of heap
f.Charging of MOS transistor
g.Question on current change in mor due to change in Vge.
h.Time constant of RL network
i.One more question on RL network
j.Solve the K-Map
k.Resistance of MOS transistor when the W/L relation is given
l.Which of then is memory related op, Buddying, monitor.
PART - B
1.Question on counter (divide by 4, 50% DC)
2.4,s Complement of a no.
3.Max operating frequency of a sequential network (166.66 MHz)
4.Some que on microprocessor. Block diagram was given
5.Sampling is done at 210 Hz of a signal containing 50., 100 & 150 Hz signal. Then the signal is passed there a LPF of 10.5 Mz cut off freq. What is the freq. component of the output
6.There are poles of OP at 10 KHz Find the value of R1 & R2.
7.Some question on current consolidated current source
8.A signal contain band limited signal B0, 2B0, 3B0.......... NB0. Each of them is sampled at nygyist rate and quatind to 8 bit. Now what is bit rate?
9.Find out noise margins of digital circuit V0,V10, V12, V02, I0n, I......... were given
10.PCM. The no. of bits is microased from 6 to 8. What is the ratio of SNR and bandwidth
11.V0/V1= jwt+ 104*2 / jw+ 104 w= 104

V1 = Cor (wt) Now determine V0.

Ans were in the form of Cos (wt + something)
Sin (wt + something)
ley (wt + something)

12. Multivibration using 555
13. Some question on transmission line.
All the 3 sections was compulsary and u,ve to give a preference among the section 2 & sec 3 so that the weightage for the second one will get doubled. Negative marking was there.

here are some of the ques which i remember

1. which conversion is not possible
a. float to int
b. int to float
c. char to float
d. all are possible
Ans: d

2. threads have which thing in common
a. register set
b. data section
c. thread id
d. ...
Ans : b

3. one que like
main()
{
int x=5, y;
y= x*x++ * ++x ;

// print x and y
}

4. A CPU has four group of instruction set A, B, C, D
CPI of A = 1
CPI of B=3
Cpi of c =2
cpi of d= 4
the cpu access 20% of A, 30% of b, 30% of C and 20 % of D
what will be the average CPI.

Ans: 1*20/100 + 3* 30/100 + 2* 30/100 + 4* 20/100
( this que was repeated in section 2 & 3)

5 . a question on hit ratio n effective memory access time.

6. main()
{
int a=10,b=5
while ( --b>=0 && ++a)
{
--b;
++a;
}
print (a);
print (b);
}
ans: a=16, b=-2

7. main()
{
char i;

for (i=0; i<=255; i++)
{
printf("%c", i);
}
}
Ans: never ending loop

8. One question on controls systems
to find the transfer functn
poles n zeroes were given in a graph
ans: s(s-2)/(s-3)(s-4)

9. one question on sampling theorem, if sampling frequency is fs then the signal having same characteistics will be of frequency....(in terns of fs)

10. one on the signal to noise ratio
- if the amplitude of the signal is reduced to half & N bits samples r used with M quantiztn level, then the SNR will be reduced by a factor of
Ans: 6 db

11. questn on calculating the bit rate to be transmitted across the given capacity channel

12. calculating the checksum for the bits to be transmitted given the frame- 11000101 and generator is1100.

13. calculating the no of bits required for the error detection & the error correction for the given codeword set.
codeword a:
0000
0001
0011
1111
codeword b:
101111
.
.
.
.
110101

14. options were given to choose as which was an example of multitasking.
a:multiple remote users accessing a server
b:user working on spreadsheet, downloading some matter from internet
c:multiple programs resident in memory

15. CA in CSMA/ CA stands for
a. collision approval
b. collision avoidance
c. critical access

16. in a triangle, without changing the angle, if we double the sides,then new area will be
asn. four times

17. there is a pipe having dia 6mm, then how many pipes having 1mm dia wiill be needed to provide same amount of water.
ans . 36

18. in which of the folwng schemes after page replacement the entered page will enter in the same memory location as of the replaced one
a. direct mapping ( Ans)
b. n-set associative
c. associative
d. none of them

19. belady anamoly is related to.
ans. page replacement algos

20.which one uses cache mechanism
ans TLB

21.what will happen in following code..
signal(mutex)
critical section
wait(mutex)

ans. violation of mutual exclusion

22.an RLC ckt was given, fuctioning of ckt to be determined.
a: will act like FM
b: PM
c:AM
d: none of the above

23.
int i=0;
switch(i)
{
case 1: printf("hi");
case 0: printf("zero");
case 2: printf("world");
}

ans: zeroworld

24.which one is the declaration of static string
a: static string
b: ,static string,
c: "static string"
d:char sting[30]

25.a que on file handling in c
a: file cant be opened
b:msg.txt is copied to msg
c:only first string be copied
d:

26. which of the fuction will store a 100 char string in X
a: fread(x,100,....)
b. fread(100,x,.......)
c.gets(x)
d.read(x)

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