Technical Aptitude

1. A 2MB PCM (pulse code modulation) has
a) 32 channels
b) 30 voice channels & 1 signaling channel.
c) 31 voice channels & 1 signaling channel.
d) 32 channels out of which 30 voice channels, 1 signaling channel, & 1 Synchronization channel.
Ans: (c)

2. Time taken for 1 satellite hop in voice communication is
a) 1/2 second b) 1 seconds c) 4 seconds d) 2 seconds
Ans: (a)

3. Max number of satellite hops allowed in voice communication is:
a) only one b) more than one c) two hops d) four hops
Ans: (c)

4. What is the maximum Decimal number that can be accommodated in a byte?
a) 128 b) 256 c) 255 d) 512
Ans: (c)

5. Conditional results after execution of an instruction in a micro processor is stored in
a) register b) accumulator c) flag register d) Program Status Word
Ans: (d)

6. Frequency at which VOICE is sampled is
a) 4 Khz b) 8 Khz c) 16 Khz d) 64 Khz
Ans: (a)

7. Line of Sight is
a) Straight Line
b) Parabolic
c) Tx & Rx should be visible to each other
d) none
Ans: (c)

8. Purpose of PC (Program Counter) in a Microprocessor is
a) To store address of TOS (Top Of Stack)
b) To store address of next instruction to be executed.
c) Count the number of instructions.
d) To store base address of the stack.
Ans: (b)

9. What action is taken when the processor under execution is interrupted by a non-maskable interrupt?
a) Processor serves the interrupt request after completing the execution of the current instruction.
b) Processor serves the interrupt request after completing the current task.
c) Processor serves the interrupt request immediately.
d) Processor serving the interrupt request depends upon the priority of the current task under execution.
Ans: (a)

10. The status of the Kernel is
a) task b) process c) not defined. d) None of the above.
Ans: (b)

11. To send a data packet using datagram , connection will be established
a) before data transmission.
b) connection is not established before data transmission
c) no connection is required.
d) none of the above.
Ans: (c)

12. Word alignment is
a) Aligning the address to the next word boundary of the machine.
b) Aligning to even boundary.
c) Aligning to word boundary.
d) None of the above.
Ans: (a)

13 When a 'C' function call is made, the order in which parameters passed to the function are pushed into the stack is
a) left to right b) right to left
c) bigger variables are moved first than the smaller variables.
d) smaller variables are moved first than the bigger ones. e) none of the above.
Ans: (b)

14 What is the type of signaling used between two exchanges?
a) inband
b) common channel signaling
c) any of the above
d) none of the above.
Ans: (a)

15 Buffering is
a) the process of temporarily storing the data to allow for small variation in device speeds
b) a method to reduce cross talks
c) storage of data within transmitting medium until the receiver is ready to receive.
d) a method to reduce routing overhead.
Ans: (a)

16. Memory allocation of variables declared in a program is
a) allocated in RAM.
b) allocated in ROM.
c) allocated on stack.
d) assigned to registers.
Ans: (c)

17. A software that allows a personal computer to pretend as a computer terminal is
a) terminal adapter
b) bulletin board
c) modem
d) terminal emulation
Ans: (d)

18. Find the output of the following program
int *p,*q;
p=(int *)1000;
q=(int *)2000;
printf("%d",(q-p));
Ans: 500

19. Which addressing mode is used in the following statements?
(a) MVI B, 55
(b) MOV B, A
(c) MOV M, A
Ans. (a) Immediate addressing mode.
(b) Register Addressing Mode
(c) Direct addressing mode

20. RS-232C standard is used in _____________.
Ans. Serial I/O

21. Memory. Management in Operating Systems is done by
a) Memory Management Unit
b) Memory management software of the Operating System
c) Kernel
Ans: (b)

22. What is done for a Push opertion?
Ans: SP is decremented and then the value is stored.

23. Binary equivalent of 52
Ans. 110100

24. Hexadecimal equivalent of 3452
Ans. D7C

25. Explain Just In Time Concept ?
Ans. Elimination of waste by purchasing manufacturing exactly when needed

26. A good way of unit testing s/w program is
Ans. User test

27. OOT uses
Ans. Encapsulated of detect methods

28.EDI useful in
Ans. Electronic Transmission

29. MRPII different from MRP
Ans. Modular version of man redundant initials

30. Hard disk time for R/W head to move to correct sector
Ans. Latency Time

31. The percentage of times a page number bound in associate register is called
Ans. Bit ratio

32. Expand MODEM
Ans. Modulator and Demodulator

33. RDBMS file system can be defined as
Ans. Interrelated

34. Super Key is
Ans. Primary key and Attribute

35. Windows 95 supports
(a) Multiuser (b) n tasks (c) Both (d) None
Ans. (a)

36.In the command scanf, h is used for
Ans. Short int

37.A process is defined as
Ans. Program in execution

38.A thread is
Ans. Detachable unit of executable code)

39.What is the advantage of Win NT over Win 95
Ans. Robust and secure

40.How is memory management done in Win95
Ans. Through paging and segmentation

41.What is meant by polymorphism
Ans. Redefinition of a base class method in a derived class

42.What is the essential feature of inheritance
Ans. All properties of existing class are derived

43.What does the protocol FTP do
Ans. Transfer a file b/w stations with user authentication

44.In the transport layer ,TCP is what type of protocol
Ans. Connection oriented

45.Why is a gateway used
Ans. To connect incompatible networks

46.How is linked list implemented
Ans. By referential structures

47.What method is used in Win95 in multitasking
Ans. Non preemptive check

48.What is a semaphore
Ans. A method synchronization of multiple processes

49.What is the precedence order from high to low, of the symbols ( ) ++ /
Ans.( ) , ++, /

50.Preorder of A*(B+C)/D-G
Ans.*+ABC/-DG

51.What is the efficiency of merge sort
Ans. O(n log n)

52.In which layer are routers used
Ans. In network layer

53.Which of the following sorting algorithm has average sorting behavior -- Bubble sort, merge sort, heap sort, exchange sort
Ans. Heap sort

54.In binary search tree which traversal is used for getting ascending order values--Inorder , post order, preorder
Ans. Inorder

55.What are device drivers used for
Ans.To provide software for enabling the hardware

56.What is fork command in unix
Ans. System call used to create process

57.What is make command in unix
Ans. Used for creation of more than one file

58.In unix .profile contains
Ans. Start up program

59.In unix 'ls 'stores contents in
Ans.inode block

60. Which of the following involves context switch,
(a) system call
(b) priviliged instruction
(c) floating poitnt exception
(d) all the above
(e) none of the above
Ans: (a)

61. In OST, terminal emulation is done in
(a) sessions layer
(b) application layer
(c) presentation layer
(d) transport layer
Ans: (b)

62. For 1 MB memory, the number of address lines required,
(a)11 (b)16 (c)22 (d) 24
Ans. (b)

63. Semaphore is used for
(a) synchronization (b) dead-lock avoidance (c) box (d) none
Ans. (a)

64. Which holds true for the following statement
class c: public A, public B
a) 2 member in class A, B should not have same name
b) 2 member in class A, C should not have same name
c) both
d) none
Ans. (a)

65.Preproconia.. does not do which one of the following
(a) macro
(b) conditional compliclation
(c) in type checking
(d) including load file
Ans. (c)

66. Piggy backing is a technique for
a) Flow control
b) Sequence
c) Acknowledgement
d) retransmition
Ans. (c)

67. Which is not a memory management scheme?
a) buddy system
b) swapping
c) monitors
d) paging
Ans : c

68. There was a circuit given using three nand gates with two inputs and one output. Find the output.
a) OR b) AND c) XOR d) NOT
Ans. (a)

69. Integrated check value (ICV) are used as:
Ans. The client computes the ICV and then compares it with the sender’s value.

70. When applets are downloaded from web sites, a byte verifier performs _________?
Ans. Status check.

71. An IP/IPX packet received by a computer using... having IP/IPX both how the packet is handled.
Ans. Read the, field in the packet header with to send IP or IPX protocol.

72. The UNIX shell....
a) does not come with the rest of the system
b) forms the interface between the user and the kernal
c) does not give any scope for programming
d) does not allow calling one program from with in another
e) all of the above
Ans. (b)

73. In UNIX a files i-node......?
Ans. Is a data structure that defines all specifications of a file like the file size, number of lines to a file, permissions etc.

74. The very first process created by the kernel that runs till the kernel process is halts is
a) Init b) Getty c) both (a) and (b) d) none of these
Ans. (a)

75. In the process table entry for the kernel process, the process id value is
(a) 0 (b) 1 (c) 2 (d) 255 (e) it does not have a process table entry
Ans. (a)

76. Which of the following API is used to hide a window
a) ShowWindow
b) EnableWindow c) MoveWindow
d) SetWindowPlacement
e) None of the above
Ans. (a)

77. Which function is the entry point for a DLL in MS Windows 3.1
a) Main b) Winmain c) Dllmain d) Libmain e) None
Ans. (b)

78. The standard source for standard input, standard output and standard error is
a) the terminal b) /dev/null
c) /usr/you/input, /usr/you/output/, /usr/you/error respectively d) None
Ans. (a)

79. The redirection operators > and >>
a) do the same function
b) differ : > overwrites, while >> appends
c) differ : > is used for input while >> is used for output
d) differ : > write to any file while >> write only to standard output e) None of these
Ans. (b)

80. The command grep first second third /usr/you/myfile
a) prints lines containing the words first, second or third from the file /usr/you/myfile
b) searches for lines containing the pattern first in the files second, third, and /usr/you/myfile and prints them
c) searches the files /usr/you/myfiel and third for lines containing the words first or second and prints them
d) replaces the word first with the word second in the files third and /usr/you/myfile
e) None of the above
Ans. (b)

81. You are creating a Index on EMPNO column in the EMPLOYEE table. Which statement will you use?
a) CREATE INdEX emp_empno_idx ON employee, empno;
b) CREATE INdEX emp_empno_idx FOR employee, empno;
c) CREATE INdEX emp_empno_idx ON employee(empno);
d) CREATE emp_empno_idx INdEX ON employee(empno);
Ans. C

82. Which program construct must return a value?
a) Package
b) Function
c) Anonymous block
d) Stored Procedure
e) Application Procedure
Ans. B

83. Which Statement would you use to remove the EMPLOYEE_Id_PK PRIMARY KEY constraint and all depending constraints from the EMPLOYEE table?
a) ALTER TABLE employee DROP PRIMARY KEY CASCADE;
b) ALTER TABLE employee dELETE PRIMARY KEY CASCAdE;
c) MOdIFY TABLE employee dROP CONSTRAINT employee_id_pk CASCAdE;
d) ALTER TABLE employee dROP PRIMARY KEY employee_id_pk CASCAdE;
e) MOdIFY TABLE employee dELETE PRIMARY KEY employee_id_pk CASCAdE;
Ans. A

84. Which three commands cause a transaction to end? (Choose three)
a) ALTER b) GRANT c) DELETE d) INSERT e) UPDATE f) ROLLBACK
Ans. a ,b ,f

85. Under which circumstance should you create an index on a table?
a) The table is small.
b) The table is updated frequently.
c) A columns values are static and contain a narrow range of values
d) Two columns are consistently used in the WHERE clause join condition of SELECT statements.
Ans.d

86. What was the first name given to Java Programming Language.
a) Oak – Java b) Small Talk c) Oak d) None
Ans.a

87.When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is such that it acts
(a) In the backward direction on the front wheel and in the forward direction on the rear wheel.
(b) In the forward direction on the front wheel and in the backward direction on the rear wheel.
(c) In the backward direction on both the front and rear wheels.
(d) In the backward direction on both the front and rear wheels.
Ans. (d)

88. A certain radioactive element A, has a half life = t seconds. In (t/2) seconds the fraction of the initial quantity of the element so far decayed is nearly
(a) 29% (b) 15% (c) 10% (d) 45%
Ans. (a)

89. Which of the following plots would be a straight line?
(a) Logarithm of decay rate against logarithm of time
(b) Logarithm of decay rate against logarithm of number of decaying nuclei
(c) Decay rate against time
(d) Number of decaying nuclei against time
Ans. (b)

90. A radioactive element x has an atomic number of 100. It decays directly into an element y which decays directly into element z. In both processes a charged particle is emitted. Which of the following statements would be true?
(a) y has an atomic number of 102
(b) y has an atomic number of 101
(c) z has an atomic number of 100
(d) z has an atomic number of 101
Ans. (b)

91. If the sum of the roots of the equation ax2 + bx + c=0 is equal to the sum of the squares of their reciprocals then a/c, b/a, c/b are in
(a) AP (b) GP (c) HP (d) None of these
Ans. (c)

92. A man speaks the truth 3 out of 4 times. He throws a die and reports it to be a 6. What is the probability of it being a 6?
(a) 3/8 (b) 5/8 (c) ¾ (d) None of the above
Ans. (a)

93. If cos2A + cos2B + cos2C = 1 then ABC is a
(a) Right angle triangle
(b) Equilateral triangle
(c) All the angles are acute
(d) None of these
Ans. (a)

94. Image of point (3, 8) in the line x + 3y = 7 is
(a) (-1,-4) (b) (-1,4) (c) (2,-4) (d) (-2,-4)
Ans. (a)

95. The mass number of a nucleus is
(a) Always less than its atomic number (b) Always more than its atomic number
(c) Sometimes more than and sometimes equals to its atomic number
(d) None of the above
Ans. (c)

96. The maximum KE of the photoelectron emitted from a surface is dependent on
(a) The intensity of incident radiation
(b) The potential of the collector electrode
(c) The frequency of incident radiation
(d) The angle of incidence of radiation of the surface
Ans. (c)

97. Which of the following is not an essential condition for interference?
(a) The two interfering waves must be propagated in almost the same direction or the two interfering waves must intersect at a very small angle
(b) The waves must have the same time period and wavelength
(c) Amplitude of the two waves should be the same
(d) The interfering beams of light must originate from the same source
Ans. (c)

98. When X-Ray photons collide with electrons
(a) They slow down
(b) Their mass increases
(c) Their wave length increases
(d) Their energy decreases
Ans. (c)

99. An electron emits energy
(a) Because its in orbit
(b) When it jumps from one energy level to another
(c) Electrons are attracted towards the nucleus
(d) The electrostatic force is insufficient to hold the electrons in orbits
Ans. (b)

100. How many bonds are present in CO2 molecule?
(a) 1 (b) 2 (c) 0 (d) 4
Ans. (d)
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UNIX O/S Tutorial

1. How are devices represented in UNIX?

All devices are represented by files called special files that are located in/dev directory. Thus, device files and other files are named and accessed in the same way. A 'regular file' is just an ordinary data file in the disk. A 'block special file' represents a device with characteristics similar to a disk (data transfer in terms of blocks). A 'character special file' represents a device with characteristics similar to a keyboard (data transfer is by stream of bits in sequential order).

2. What is 'inode'?

All UNIX files have its description stored in a structure called 'inode'. The inode contains info about the file-size, its location, time of last access, time of last modification, permission and so on. Directories are also represented as files and have an associated inode. In addition to descriptions about the file, the inode contains pointers to the data blocks of the file. If the file is large, inode has indirect pointer to a block of pointers to additional data blocks (this further aggregates for larger files). A block is typically 8k.

Inode consists of the following fields:

 File owner identifierØ

 File typeØ

 File access permissionsØ

 File access timesØ

 Number of linksØ

 File sizeØ

 Location of the file dataØ

3. Brief about the directory representation in UNIX

A Unix directory is a file containing a correspondence between filenames and inodes. A directory is a special file that the kernel maintains. Only kernel modifies directories, but processes can read directories. The contents of a directory are a list of filename and inode number pairs. When new directories are created, kernel makes two entries named '.' (refers to the directory itself) and '..' (refers to parent directory).

System call for creating directory is mkdir (pathname, mode).

4. What are the Unix system calls for I/O?

 open(pathname,flag,mode) - open fileØ

 creat(pathname,mode) - create fileØ

 close(filedes) - close an open fileØ

 read(filedes,buffer,bytes) - read data from an open fileØ

 write(filedes,buffer,bytes) - write data to an open fileØ

 lseek(filedes,offset,from) - position an open fileØ

 dup(filedes) - duplicate an existing file descriptorØ

 dup2(oldfd,newfd) - duplicate to a desired file descriptorØ

 fcntl(filedes,cmd,arg) - change properties of an open fileØ

 ioctl(filedes,request,arg) - change the behaviour of an open fileØ

The difference between fcntl anf ioctl is that the former is intended for any open file, while the latter is for device-specific operations.

5. How do you change File Access Permissions?

Every file has following attributes:

 owner's user ID ( 16 bit integer )Ø

 owner's group ID ( 16 bit integer )Ø

 File access mode wordØ

'r w x -r w x- r w x'

(user permission-group permission-others permission)

r-read, w-write, x-execute

To change the access mode, we use chmod(filename,mode).

Example 1:

To change mode of myfile to 'rw-rw-r--' (ie. read, write permission for user - read,write permission for group - only read permission for others) we give the args as:

chmod(myfile,0664) .

Each operation is represented by discrete values

'r' is 4

'w' is 2

'x' is 1

Therefore, for 'rw' the value is 6(4+2).

Example 2:

To change mode of myfile to 'rwxr--r--' we give the args as:

chmod(myfile,0744).

6. What are links and symbolic links in UNIX file system?

A link is a second name (not a file) for a file. Links can be used to assign more than one name to a file, but cannot be used to assign a directory more than one name or link filenames on different computers.

Symbolic link 'is' a file that only contains the name of another file.Operation on the symbolic link is directed to the file pointed by the it.Both the limitations of links are eliminated in symbolic links.

Commands for linking files are:

Link ln filename1 filename2

Symbolic link ln -s filename1 filename2

7. What is a FIFO?

FIFO are otherwise called as 'named pipes'. FIFO (first-in-first-out) is a special file which is said to be data transient. Once data is read from named pipe, it cannot be read again. Also, data can be read only in the order written. It is used in interprocess communication where a process writes to one end of the pipe (producer) and the other reads from the other end (consumer).

8. How do you create special files like named pipes and device files?

The system call mknod creates special files in the following sequence.

1. kernel assigns new inode,

2. sets the file type to indicate that the file is a pipe, directory or special file,

3. If it is a device file, it makes the other entries like major, minor device numbers.

For example:

If the device is a disk, major device number refers to the disk controller and minor device number is the disk.

9. Discuss the mount and unmount system calls

The privileged mount system call is used to attach a file system to a directory of another file system; the unmount system call detaches a file system. When you mount another file system on to your directory, you are essentially splicing one directory tree onto a branch in another directory tree. The first argument to mount call is the mount point, that is , a directory in the current file naming system. The second argument is the file system to mount to that point. When you insert a cdrom to your unix system's drive, the file system in the cdrom automatically mounts to /dev/cdrom in your system.

10. How does the inode map to data block of a file?

Inode has 13 block addresses. The first 10 are direct block addresses of the first 10 data blocks in the file. The 11th address points to a one-level index block. The 12th address points to a two-level (double in-direction) index block. The 13th address points to a three-level(triple in-direction)index block. This provides a very large maximum file size with efficient access to large files, but also small files are accessed directly in one disk read.

11. What is a shell?

A shell is an interactive user interface to an operating system services that allows an user to enter commands as character strings or through a graphical user interface. The shell converts them to system calls to the OS or forks off a process to execute the command. System call results and other information from the OS are presented to the user through an interactive interface. Commonly used shells are sh,csh,ks etc.

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