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CBSE Important Questions

CBSE Guess > Papers > Important Questions > Class XI > 2010 >Computer Science >Computer Science By Mr. Ravi Kiran

CBSE CLASS XI

Q.1. Differentiate between primary memory and secondary memory. Give examples of each type of memory.
a) The memory inside the CPU is primary memory (main memory) and the memory outside it is known as secondary(auxiliary) memory.
Primary Memory: RAM (Random Access Memory) and ROM (Read only Memory) comes under primary memory. RAM is volatile memory and ROM is non volatile memory. All the data and programs must be stored in RAM for execution. But the content of RAM is not permanent. Eg: RAM, ROM.

Secondary Memory: Since primary memory has a limited storage capacity and is not permanent, secondary storage devices are used to store large amount of data permanently. There are various types of secondary devices available these days.
Eg: Hard disks, Floppy disks ----- Magnetic Media
CD ROMS, DVDs ----- Optical Media

Q.2. Expand the following:
i)CPU ii) ROM iii)MICR iv)CD-R 2

a) (i) CPU - Central Processing Unit
(ii)ROM - Read Only Memory
(iii)MICR – Magnetic Ink Character Reader
(iv) CD –R – Compact Dist Recordable

Q.3. Explain briefly the functions of ALU.

a) The Arithmetic and Logic Unit performs all the four arithmetical (+,-,*,/) and some logical (<,<=,>,>=,< >) operations. When two numbers are required to be added, these numbers are sent from memory to ALU where addition takes place and the result is put back in the memory. In the same way other arithmetic operations are performed.
For logical operations also, the numbers to be compared are sent from memory to ALU where the comparison takes place and the result is returned to the memory. The result of a logical operation is either TRUE or FALSE. These operations provide the capability of decision-making to the computer.

II Q.1. What is the difference between semantics error and syntax error? Give an example of each.

a) 1.Syntax Errors: Syntax errors occur when rules of a programming language are misused.
Syntax refers to formal rules governing the construction of valid statements in a language.
Eg: int a,b //Did not keep ; (semicolon) at the end of statement.

Q.2. Semantics Error: Semantic errors occur when statements are not meaningful.Semantics refers to the set of rules which give the meaning of a statement.
Eg: X * Y = Z;
(Siva plays Guitar is Syntactically and Semantically correct but Guitar plays Siva is Syntactically correct but Semantically incorrect).

Q2. Write an algorithm to find xy. 2
a) Step1: Start
Step2: Declare x, y as integers
Step3: Output “Enter the value of x and y ie base and exponent”
Step 4:Read x,y
Step 5:Output “The result of the expression =”, pow(x,y)
Step 6: Stop

Q.3.What is data abstraction? Explain the concept with the help of an example.
a) Abstraction: Abstraction refers to the act of representing essential features without including the background details or explanations.
Eg: If you talk about student details, complete details are his rollno, admissionno,
name, m1, m2, m3, total, avg, grade, fathername, address, pin, etc……
But abstraction about his marks are…
Rollno,admissionno,name,m1,m2,m3,total,avg,grade.

Paper By Mr. Ravi Kiran
Email Id :mrkdata@yahoo.com