Short description of CS

Computer science deals with the theoretical foundations of information and computation, together with practical techniques for the implementation and application of these foundations

Computer Science (abbreviated CS or CompSci) is the scientific and practical approach to computation and its applications. It is the systematic study of the feasibility, structure, expression, and mechanization of the methodical processes (or algorithms) that underlie the acquisition, representation, processing, storage, communication of, and access to information, whether such information is encoded as bits in a computer memory or transcribed in genes and protein structures in a human cell.

History: The earliest foundations of what would become computer science predate the invention of the modern digital computer. Machines for calculating fixed numerical tasks such as the abacus have existed since antiquity, aiding in computations such as multiplication and division.

• Charles Babbage is credited with inventing the first mechanical computer
• Ada Lovelace is credited with writing the first algorithm intended for processing on a computer.
• The German military used the Enigma machine (shown here) during World War II for communication they thought to be secret. The large-scale decryption of Enigma traffic at Bletchley Park was an important factor that contributed to Allied victory in WWII

Computer Science is not just about building computers or writing computer programs! Computer Science is no more about building computers and developing software than astronomy is about building telescopes, biology is about building microscopes, and music is about building musical instruments! Computer science is not about the tools we use to carry out computation. It is about how we use such tools, and what we find out when we do. The solution of many computer science problems may not even require the use of computers—just pencil and paper. As a matter of fact, problems in computer science have been tackled decades before computers were even built. That said the design and implementation of computing system hardware and software is replete with formidable challenges and fundamental problems that keep computer scientists busy. Computer Science is about building computers and writing computer programs, and much more!

Solve more questions on networking -Computer Science

1. The network number plays what part in an IP address?
A. It specifies the network to which the host belongs.
B. It specifies the identity of the computer on the network.
C. It specifies which node on the sub-network is being addressed.
D. It specifies which networks the device can communicate with.

Answer :- A. It specifies the network to which the host belongs.

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 2. What is the decimal equivalent to the binary number 101101?
A. 32
B. 35
C. 45
D. 44

Answer :-  C. 45

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3. Convert the following decimal number to its binary form: 192.5.34. 11.

A. 11000000.00000101.00100010.00001011
B. 11000101.01010111.00011000.10111000
C. 01001011.10010011.00111001.00110111
D. 11000000.00001010.01000010.00001011


Answer:- A. 11000000.00000101.00100010.00001011

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 4. Convert the following binary IP address to its decimal form: 11000000.00000101.00100010.00001011 A. 190.4.34.11
B. 192.4.34.10
C. 192.4.32.11
D. None of the above

Answer:- D. None of the above

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 5. What portion of the following Class B address is the network address: 154.19.2.7?
A. 154
B. 154.19
C. 154.19.2
D. 154.19.2.7

Answer:- B. 154.19

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6. Which portion of the IP address 129.219.51.18 represents the network?
A. 129.219
B. 129
C. 51.18
D. 18

Answer:-  A. 129.219

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7. Which address is an example of a broadcast address on the network 123.10.0.0 with a subnet mask of 255.255.0.0?
A. 123.255.255.255
B. 123.10.255.255
C. 123.13.0.0
D. 123.1.1.1

Answer:-   B. 123.10.255.255

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8. MAC address are _________ bits in length.
A. 12
B. 24
C. 48
D. 64


Answer :- C.  48

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9. Where does the MAC address reside?

A. Transceiver
B. Computer BIOS
C. NIC
D. CMOS

Answer :- C.  NIC

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10.Convert the decimal number 2989 to hex.
A. FDD1
B. BAD
C. TED
D. CAD

Answer  :- B.  BAD

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Solve questions on Networking

1. How many bits are in an IP address?

A. 16 bits
B. 32 bits
C. 64 bits
D. None of the above

Answer :- B.32 bits

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2. What is the maximum value of each octet in an IP address?
A. 128
B. 255
C. 256
D. None of the above

Answer :- B. 255

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3. How many bits are in a subnet mask?
A. 16 bits
B. 32 bits
C. 64 bits
D. None of the above

Answer :- B. 32 bits

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4. A half-duplex circuit means
A. Only one side can talk at a time
B. The signal strength is cut in half
C. The signal strength is doubled
D. Two hosts can talk simultaneously

Answer :- A. Only one side can talk at a time

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5. Attenuation means
A. Travel
B. Delay
C. A signal losing strength over distance
D. Loss of signal due to EMI

Answer :- C. A signal losing strength over distance

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6. __________ means to convert binary data into a form that can travel on a physical communications link.
A. Encoding
B. Decoding
C. Encrypting
D. Decrypting

Answer :- A.Encoding

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7. How many host addresses can be used in a Class C network?
A. 253
B. 254
C. 255
D. 256

Answer :- B. 254

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8. What is the minimum number of bits that can be borrowed to form a subnet?
A. 1
B. 2
C. 4
D. None of the above

Answer :- B. 2

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9. What is the primary reason for using subnets?
A. To reduce the size of the collision domain
B. To increase the number of host addresses
C. To reduce the size of the broadcast domain
D. None of the above

Answer :- C. To reduce the size of the broadcast domain

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10.How many bits can be borrowed to create a subnet for a Class C network?
A. 2
B. 4
C. 6
D. None of the above

Answer :- C. 6

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Study material of Computer Science :-

127.0.0.1 is is a special purpose IP address conventionally used as a computer's loopback address.

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Definition Thrashing :-
In computer science, thrashing occurs when a computer's virtual memory subsystem is in a constant state of paging, rapidly exchanging data in memory for data on disk, to the exclusion of most application-level processing

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Virtual Memory:-
In computing, virtual memory is a memory management technique that is implemented using both hardware and software. It maps memory addresses used by a program, called virtual addresses, into physical addresses in computer memory. Main storage as seen by a process or task appears as a contiguous address space or collection of contiguous segments.

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The time taken to move the disk arm to the desired cylinder is called the :seek time

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Class A
0    . 0   . 0   . 0      =  00000000.00000000.00000000.00000000
127.255.255.255   =  01111111.11111111.11111111.11111111
                                  0nnnnnnn.HHHHHHHH.HHHHHHHH.HHHHHHHH
Class B
128. 0. 0. 0          = 10000000.00000000.00000000.00000000
191.255.255.255 = 10111111.11111111.11111111.11111111
                               10nnnnnn.nnnnnnnn.HHHHHHHH.HHHHHHHH
Class C
192. 0. 0. 0          = 11000000.00000000.00000000.00000000
223.255.255.255 = 11011111.11111111.11111111.11111111
                               110nnnnn.nnnnnnnn.nnnnnnnn.HHHHHHHH
Class D
224. 0. 0. 0          = 11100000.00000000.00000000.00000000
239.255.255.255 = 11101111.11111111.11111111.11111111
                               1110XXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX
Class E
240. 0. 0. 0          = 11110000.00000000.00000000.00000000
255.255.255.255 = 11111111.11111111.11111111.11111111
                               1111XXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX
Where:
n indicates a binary slot used for network ID.
H indicates a binary slot used for host ID.
X indicates a binary slot (without specified purpose)

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190.255.254.254 -class B

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Solve Practice questions of Computer Science

1. Decryption & Encryption of data are the responsibility of the ___ layer.

(A) Physical
(B) Data link
(C) Presentation
(D) Session
(E) Application

Answer :- (C) Presentation

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2. LANs can be connected by devices called ____ which operate in the data link layer?

(A) Hub
(B) Bridges
(C) HDLC
(D) Tunnel
(E) None of these

Answer :- (B) Bridges

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Multiplexers

Multiplexer :-
                        It is known as MUX..
                        Multiplexing is the process of connecting many inputs to one output it is "many into one " process with appropriate logic control signals.
                        Multiplexer is a basic block or basic logic combinational circuit with
i) 'n' input lines
ii) 'm' control lines / selector lines
iii) one output line 'Y'

    It requires OR gate in the O/P.
  
   It cannot be used as a decoder.

   Example :- IC 74153,74157
 To calculate Select line  -  Formula :-         2^m = n
where, n is the input lines
            m is the control lines

4:1 Multiplexer :
Truth table :-

S1	S0	Y =
0	0	D0
0	1	D1
1	0	D2
1	1	D3

It has 4 input lines (D0 ,D1,D2,D3) two control lines (S1 S0) called  select lines and one output line by 'Y'
Working:-
1) When the control word is S1 and S0 is 0 0 then Y = D0
2) When the control word is S1 and S0 is 0 1 then Y = D1
3) When the control word is S1 and S0 is 1 0 then Y = D2
4) When the control word is S1 and S0 is 1 1 then Y = D3

Note that at any instant only one AND is enabled allowing only one data line transmission to the common output line.

Solve questions

1.In relational database row and column is called as ____and ____respectively.

(A)Tuple; Attribute
(B)Attribute; Tuple
(C)Tupple;Domain
(D)Attribute; Domain
(E)None of these

Answer :- (A)Tuple; Attribute

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2.Arrange the following in increasing order of their size.

 (A) Database<File<Record<Field<Byte<Bit
 (B) Bit<Byte<Field<Record<File<Database
 (C) Bit>Byte>Record>Field>File>Database
 (D) Bit>Byte>File>Record>Field>Database


Answer :-   (B) Bit<Byte<Field<Record<File<Database

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3. Round robin scheduling is essentially the preemptive version of

(A) FIFO
(B)Shortest job first
(C) Shortest remaining
(D)Longest time first
(E) None of these

Answer :- (A) FIFO

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4. Which of the following identifies specific web page and its computer on the web page?

(A) Web site
(B) URL
(C) Web site address
(D) Domain Name
(E) None of these

Answer :- (B) URL

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5.Communication handler is basically an ____ 16 bit micro controller?

(A) 8085
(B) 8086
(C) 8086A
(D) 80C186
(E) None of these

Answer :- (D) 80C186

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6.GSM stands for ____

(A) General System for Mobile Communication
(B)Global System for Mobile Communication
(C) Guided System for Mobile Communication
(D) Growing System for Mobile Communication
(E) None of these

Answer :- (B) Global System for Mobile Communication

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7.EDI refers to ----

(A) Electronic Data Interface
(B) Electric Device Interface
(C) Electronic Data Interchange
(D)Electronic Design Interface

Answer :- (C) Electronic Data Interchange

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8.PAN refers to_____

(A) Peer Area Network
(B) Personnel Area Network
(C) Personal Area Network
(D) Payment Application Network

Answer :- (C) Personal Area Network

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9.E-Commerce refers to ___

(A)Electrical Commerce
(B) Electronic Commerce
(C)Evolutionary Commerce
(D) Effective Commerce

Answer :- (B) Electronic Commerce

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10.Which of the following is a type of E-commerce?

(A) B2B  (Business to Business)
(B) B2C  (Business to Consumer)
(C) C2C  (Consumer to Consumer)
(D) All the above

Answer :- (D) All the above

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