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CBSE CLASS 11th – CS Easy Explaination !

In this page we will cover all the important Computer science topics in quick short manner to get your doubts cleared and have a bird's eye view to all the topics present in SUMITA ARORA's book !
Software Developer

1. Computer System Overview -

Cache Memory:

Pronounced as cash, cache memory is a special high-speed storage mechanism. It can be either a reserved section of main memory or an independent high speed storage device or even on CPU chip. Whenever some data is required, the CPU first looks in the cache, if it is there or not. If the data is found in cache, CPU does not access memory and hence the process becomes very fast.

Types of software

System Software 

A computer is mere a machine that knows nothing of itself. Rather it requires instruction for each and everything it performs. 

System software can futher be classified into two categories:



The primary goal of an operating system is thus to make the computer system convenient to use and secondary goal is to use computer hardware in an efficient manner.


A language processor is a special type of computer software that can translate the source code into an object code or machine code. 

Source code refers to the program code written a programmer in a high level programming language (HLL) such as in C, Java, C++ etc.

Application Software 

This type of software pertains to one specific application. For instance, a software that can perform railway reservation functions cannot prepare result for a school.

Application software can further be subdivided into four categories:

  1. Packages
  2. Utilities
  3. Customised Software 
  4. Developer tools

*google them seprately


The rapid growth of technology is not at all surprising but what surprises is the rate at which the technology is growing and evolving, impacting our lives in a way no one could have imagined some decades ago. 

Artificial Intelligence

Artificial Intelligence (AI) basically refers to the ability of a machine or a computer program to think and learn. In simple words, field of AI revovles around bringing out technologies that help build machine that can think, act and learn like humans.

  1. First it should be able to mimics human thought process & connection of neurons in brain cells.
  2. Secondly, it should act a human like way intelligent, think of its own past experiences.

Programmed to :-

  1. work with minimum human intervention 
  2. create and update knowledge base, which keeps updating
  3. having heuristic abilities

Other common example of AI today are :-

  1. Siri or Alexa – the personal assistant that have already become the new normal for thousands of people around the globe.
  2. smart home devices 
  3. self driving cars , like tesla
  4. online games like Alien : Isolation


Machine Learning

Machine learning is a sub-area of AI which refers ot the ability of computers to independently find solution to problems recognizing patterns in databases using statistical techniques. 

Machine Learning enables computers to recognize patterns on the basis of specific algorithns called models and data set and to develop adequate solution concepts.

Internet Of Things (IOT)

is a new age technology that allows computing devices to transfer data over a network like Internet without requiring human-to-human or human-to-computer interaction.

Cloud Computing

Cloud computing is the internet based computing, where shared resources, software and information are provided and other devices on demand, like the electricity grid.

Blockchain Technology 

It is a decentralised, digitalized, public lledger of each of the online transaction occuring among a network of peers.

5. Introduction to Problem Solving

Steve jobs’s famous quote clearly defines it, “Everyone in this country should learn to program a computer, because it teaches you to think”.

This qyorte is proof enough to say that in order to program a solution for a problem, you should think in a specific way.

Problem Solving Cycle :

Problem solving requires four main steps:


  1. Identify and analyse the problem 
  2. Find its solution and develop algorithm of the solution
  3. Code the solution in a programming language
  4. Test and Debug the coded solution.

and finally implement and maintain it.

6. Getting Started with Python

Python programming language was developed Guido Van Rossum in february 1991.

Python is influenced with ABC language and Modula-3 programming languages. Python is an easy to learn, general purpose, object oriented and a high level programming language

Practical classes contact – +91 8445490989

7. Python Fundamentals

Most, if fact nearly all daily life and computer actions are governed IPO cycle (Input, process, output)

Programs make IPO cycle happens !

Anywhere where you wnat to transform some kind of input to certain output, you have some kind of input  to certain output, you have to have a program.


in passage of text, individual words and punctutation marks are called tokens or lexical units or lexical elements. The smallest individual unit is program is know as Token or a Lexical unit. It is the term also used in natural language processing.


Keywords are the words that convey a special meaning to the language compiler/interpreter. These are reserved for special purpose and must not be used as normal identifier names.


Identifier are fundamental building blocks of a program and are used as the general terminology for the names given to different parts of the program which is variables, objects, classes, functions, lists, dictionaries etc.

Literals / Values

Literal are data items that have a fixed value. Python allows several kinds of literals

  • string literals
  • numeric literals
  • boolean literals
  • special literal none
  • literal collection


Operators are tokens that triggers some computation when applied to variable and other object in an expression. Variables and objects to which the computation is applied are called operands.

Types of operators:

  1. Unary operator
  2. Binary operator
  3. Arithmetic operator
  4. Bitwise operator
  5. Shift Operator
  6. Identity Operator
  7. Relational Operator
  8. Logical Operator
  9. Assignment Operator
  10. Membership Operator


8. Data Handling

Python provides a predefined set of data types for handling the data it uses.

Data Types

Data can be of many types e.g., character, integer, real, string, etc. Anything enclosed in quotes represents string data in Python.

Lists and Tuples

the lists and tuples are Python’s compound data types. We have taken them together in one section because they are basically the same types with one difference.

Lists can be changes modified but tuples cannot be changed or modified.

Lists in Python represents a lists of comma seperated values of any datatype between square brackets.

Tuples as those lists which cannot be changed ar not modifiable.

Mutable and Immutable types

The python data objects can be broadly categorised into two – mutable and ummutable types

Immutable types

are those that can never change their values in place. eg. string, tuples, boolean, floating point number

Mutable types

 are those whose values can be changed in place. eg. dictionaries, lists, sets.


debugging in simple English means to remove ‘bugs’ from a program. An error causing disruption in program’s running or in producing right output is a ‘program bug’. Debugging involves rectifying the code so that the reason behind the bug gets resolved and thus bug is also removed.

9. Flow of Control

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