Computer Science Class 11

Teachers and Examiners (CBSESkillEduction) collaborated to create the Functions in Python Class 11 Notes. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Functions in Python Class 11 Notes

A complex programme can be broken down into smaller programmes by using functions, and these smaller programmes, known as modules, make the programme easier to understand. A function is a piece of code that only executes when called.

Once defined, a function can be used again throughout the programme without requiring the user to write out the entire code for it each time. It can also be used inside of other functions by simply writing the function name and the necessary parameters.

The Advantages of Function

1. Increases readability, particularly for longer code as by using functions, the program is better organised and easy to understand.
2. Reduces code length as same code is not required to be written at multiple places in a program. This also makes debugging easier.
3. Increases reusability, as function can be called from another function or another program. Thus, we can reuse or build upon already defined functions and avoid repetitions of writing the same piece of code.
4. Work can be easily divided among team members and completed in parallel.

Type of Function

There are two types of function in python.

1. User – Define Function
2. Built – in – Function

The Python language includes built-in functions such as dir, len, and abs. The def keyword is used to create functions that are user specified.

Functions in Python Class 11 Notes

User – Define Function

User-defined functions are the fundamental building block of any programme and are essential for modularity and code reuse because they allow programmers to write their own function with function name that the computer can use.

Creating User Defined Function

A function definition begins with def (short for define). The syntax for creating a user defined function is as follows –

Syntax – 

def function_name(parameter1, parameter2, …) :
statement_1
statement_2
statement_3
….

• The items enclosed in “[ ]” are called parameters and they are optional. Hence, a function may or may not have parameters. Also, a function may or may not return a value.
• Function header always ends with a colon (:).
• Function name should be unique. Rules for naming identifiers also applies for function naming.
• The statements outside the function indentation are not considered as part of the function.

Q. Write a user defined function to add 2 numbers and display their sum.

#Program
#Function to add two numbers
def addnum():
fnum = int(input(“Enter first number: “))
snum = int(input(“Enter second number: “))
sum = fnum + snum
print(“The sum of “,fnum,”and “,snum,”is “,sum)
#function call
addnum()

Output:
Enter first number: 5
Enter second number: 6
The sum of 5 and 6 is 11

Functions in Python Class 11 Notes

Arguments and Parameters

User-defined function could potentially take values when it is called. A value received in the matching parameter specified in the function header and sent to the function as an argument is known as an argument.

Q. Write a program using a user defined function that displays sum of first n natural numbers, where n is passed as an argument.

#Program
#Program to find the sum of first n natural numbers
def sumSquares(n):
sum = 0
for i in range(1,n+1):
sum = sum + i
print(“The sum of first”,n,”natural numbers is: “,sum)
num = int(input(“Enter the value for n: “))
sumSquares(num) #function call

Q. Write a program using a user defined function myMean() to calculate the mean of floating values stored in a list.

#Program 7-6
#Function to calculate mean
def myMean(myList):
total = 0
count = 0
for i in myList:
total = total + i
count = count + 1
mean = total/count
print(“The calculated mean is:”,mean)
myList = [1.3,2.4,3.5,6.9]
myMean(myList)

Output:
The calculated mean is: 3.5250000000000004

Functions in Python Class 11 Notes

Q. Write a program using a user defined function calcFact() to calculate and display the factorial of a number num passed as an argument.

#Program 7-7
#Function to calculate factorial
def calcFact(num):
fact = 1
for i in range(num,0,-1):
fact = fact * i
print(“Factorial of”,num,”is”,fact)
num = int(input(“Enter the number: “))
calcFact(num)

Output:
Enter the number: 5
Factorial of 5 is 120

String as Parameters

Some programmes may require the user to supply string values as an argument.

Functions in Python Class 11 Notes

Q. Write a program using a user defined function that accepts the first name and lastname as arguments, concatenate them to get full name and displays the output as:

#Program
#Function to display full name
def fullname(first,last):
fullname = first + ” ” + last
print(“Hello”,fullname)
first = input(“Enter first name: “)
last = input(“Enter last name: “)
fullname(first,last)

Output:
Enter first name: Gyan
Enter last name: Vardhan
Hello Gyan Vardhan

Functions in Python Class 11 Notes

Default Parameter

The argument can be given a default value in Python. When a function call doesn’t have its appropriate argument, a default value is chosen in advance and given to the parameter.

Q. Write a program that accepts numerator and denominator of a fractional number and calls a user defined function mixedFraction() when the fraction formed is not a proper fraction. The default value of denominator is 1. The function displays a mixed fraction only if the fraction formed by the parameters does not evaluate to a whole number.

#Program
#Function to display mixed fraction for an improper fraction
def mixedFraction(num,deno = 1):
     remainder = num % deno
     if remainder!= 0:
         quotient = int(num/deno)
         print(“The mixed fraction=”, quotient,”(“,remainder, “/”,deno,”)”)
     else:
         print(“The given fraction evaluates to a whole number”)
num = int(input(“Enter the numerator: “))
deno = int(input(“Enter the denominator: “))
print(“You entered:”,num,”/”,deno)
if num > deno:
     mixedFraction(num,deno)
else:
     print(“It is a proper fraction”)

Output:
Enter the numerator: 17
Enter the denominator: 2
You entered: 17 / 2
The mixed fraction = 8 ( 1 / 2 )

Functions in Python Class 11 Notes

Functions Returning Value

The function’s values are returned using the return statement. A function that has finished its duty will return a value to the script or function that called it.

The return statement does the following –

• returns the control to the calling function.
• return value(s) or None.

Q. Write a program using user defined function calcPow() that accepts base and exponent as arguments and returns the value Baseexponent where Base and exponent are integers.

#Program
#Function to calculate and display base raised to the power exponent
def calcpow(number,power):
result = 1
for i in range(1,power+1):
result = result * number
return result
base = int(input(“Enter the value for the Base: “))
expo = int(input(“Enter the value for the Exponent: “))
answer = calcpow(base,expo)
print(base,”raised to the power”,expo,”is”,answer)

Output:
Enter the value for the Base: 5
Enter the value for the Exponent: 4
5 raised to the power 4 is 625

Flow of Execution

The first statement in a programme is where the Python interpreter begins to carry out the instructions. As they read from top to bottom, the statements are carried out one at a time.
The statements contained in a function definition are not executed by the interpreter until the function is called.

Scope of a Variable

An internal function variable can’t be accessed from the outside. There is a well defined accessibility for each variable. The scope of a variable is the area of the programme that the variable is accessible from. A variable may fall under either of the two scopes listed below:
A variable with a global scope is referred to as a global variable, whereas one with a local scope is referred to as a local variable.

Global Variable – A variable that is defined in Python outside of any function or block is referred to as a global variable. It is accessible from any functions defined afterward.

Local Variable – A local variable is one that is declared inside any function or block. Only the function or block where it is defined can access it.

Functions in Python Class 11 Notes

Built-in functions

The pre-made Python functions that are widely used in programmes are known as built-in functions. Let’s examine the subsequent Python programme –

#Program to calculate square of a number
a = int(input(“Enter a number: “)
b = a * a
print(” The square of “,a ,”is”, b)

In the programme mentioned above, the built-in functions input(), int(), and print() are used. The Python interpreter already defines the set of instructions that must be followed in order to use these built-in functions.

Commonly used built-in functions

Functions in Python Class 11 Notes

Module

The Python standard library includes a number of modules. A module is a collection of functions, whereas a function is a collection of instructions. suppose we have created some functions in a program and we want to
reuse them in another program. In that case, we can save those functions under a module and reuse them. A module is created as a python (.py) file containing a collection of function definitions.

To use a module, we need to import the module. Once we import a module, we can directly use all the functions
of that module. The syntax of import statement is as follows:

import modulename1 [,modulename2, …]

Built-in Modules

Let’s examine a few widely used modules and the functions that are contained in such modules:

Module name : math

Functions in Python Class 11 Notes

Module name : random

Functions in Python Class 11 Notes

Module name : statistics

Computer Science Class 11 Notes

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 MCQ

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 NCERT Solutions

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples and Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer

Teachers and Examiners (CBSESkillEduction) collaborated to create the Flow of Control in Python Class 11 Notes. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Flow of Control in Python Class 11 Notes

Selection Statement (Conditional Statement) 

Conditions are tested by selection statements, This type of statement depending on the condition and generate the result based on condition. If a condition is met in this sentence, a true block is run; else, a false block is. example of selection statement is If…Else statement and Switch Statement.

If Statement having three types –

1. If – Else Statement
2. Elif Statement
3. Nested If Statement

If – Else Statement 

If statement called if..else statement allows us to write two alternative paths and the control condition determines which path gets executed. The syntax for if..else statement is as follows.

The syntax of if statement is:
if condition:
        statement(s)
else:
        statement(s)

Q. Write a program to accept person age from the user and check weather person is eligible for vote or not.

age = int(input(“Enter your age: “))  # Taking input from the user
if age >= 18:   # Checking weather age is grater then 18 or not
print(“Eligible to vote”) #Printing the comment if age is grater then 18
else:
print(“Not eligible to vote”) #Printing the comment if age is grater then 18

Note – The int() code is used to convert string values to integer values since input codes only accept input in the form of character (Strings).

Flow of Control in Python Class 11 Notes

Program related to if statement 

Q. Program to print the positive difference of two numbers.

#Program 6-2
#Program to print the positive difference of two numbers
num1 = int(input(“Enter first number: “))
num2 = int(input(“Enter second number: “))
if num1 > num2:
diff = num1 – num2
else:
diff = num2 – num1
print(“The difference of”,num1,”and”,num2,”is”,diff)

Output:
Enter first number: 5
Enter second number: 6
The difference of 5 and 6 is 1

Flow of Control in Python Class 11 Notes

Elif Statement 

You can build a chain of if statements using the elif statement. Before the end of the elif chain is reached or one of the if expressions is true, the if statements are evaluated one at a time. If there is no true expression at the end of the elif chain, then else statement will be execuited.

The syntax for a selection structure using elif is as shown below.

if condition:
     statement(s)
elif condition:
     statement(s)
elif condition:
     statement(s)
else:
     statement(s)

Program related to if statement 

Q. Check whether a number is positive, negative, or zero.

number = int(input(“Enter a number: “)
if number > 0:
     print(“Number is positive”)
elif number < 0:
     print(“Number is negative”)
else:
print(“Number is zero”)

Flow of Control in Python Class 11 Notes

Q. Display the appropriate message as per the colour of signal at the road crossing.

signal = input(“Enter the colour: “)
if signal == “red” or signal == “RED”:
     print(“STOP”)
elif signal == “orange” or signal == “ORANGE”:
     print(“Be Slow”)
elif signal == “green” or signal == “GREEN”:
     print(“Go!”)

Q. Write a program to create a simple calculator performing only four basic operations.

#Program to create a four function calculator
result = 0
val1 = float(input(“Enter value 1: “))
val2 = float(input(“Enter value 2: “))
op = input(“Enter any one of the operator (+,-,*,/): “)
if op == “+”:
     result = val1 + val2
 elif op == “-“:
     if val1 > val2:
          result = val1 – val2
     else:
          result = val2 – val1
elif op == “*”:
     result = val1 * val2
elif op == “/”:
     if val2 == 0:
          print(“Error! Division by zero is not allowed. Program terminated”)
     else:
          result = val1/val2
else:
     print(“Wrong input,program terminated”)
     print(“The result is “,result)

Output:
Enter value 1: 84
Enter value 2: 4
Enter any one of the operator (+,-,*,/): /
The result is 21.0

Flow of Control in Python Class 11 Notes

Indentation

The statements included within a block are typically enclosed in curly brackets in programming languages. Python, however, uses indentation for both block and nested block structures. Indentation is the practise of placing leading whitespace (spaces and tabs) at the start of a sentence.

Q. Program to find the larger of the two pre-specified numbers.

#Program 6-4
#Program to find larger of the two numbers
num1 = 5
num2 = 6
if num1 > num2:                  #Block1
          print(“first number is larger”)
          print(“Bye”)
else:                                     #Block2
          print(“second number is larger”)
          print(“Bye Bye”)

Output:
second number is larger
Bye Bye

Flow of Control in Python Class 11 Notes

Repetition

Iteration  is another word for this kind of repetition. A programme can repeat a certain collection of statements by using looping constructs.

Looping – The ability to repeatedly run a group of statements in a programme based on a condition is provided by looping constructs. While a certain logical condition is true, the statements in a loop are repeated again.

There are two type of looping –

1. Entry Control Loop – The loop which check the condition first and then execuite the body of loop is known as entry control loop. example, for & while
2. Exit Control Loop – The loop which execuite the body of loop first and then check the condition is known as exit control loop. example do-while

For Loop

The for statement allows you to specify how many times a statement or compound statement should be repeated. A for statement’s body is executed one or more times until an optional condition is met.

Syntax of the For Loop

for <control-variable> in <sequence/ items in range>:
<statements inside body of the loop>

Q. Program to print the characters in the string ‘PYTHON’ using for loop.

#Program 6-6
#Print the characters in word PYTHON using for loop
for letter in ‘PYTHON’:
     print(letter)

Output:
P
Y
T
H
O
N

Q. Program to print the numbers in a given sequence using for loop.

#Program 6-7
#Print the given sequence of numbers using for loop
count = [10,20,30,40,50]
for num in count:
     print(num)

Output:
10
20
30
40
50

Q. Program to print even numbers in a given sequence using for loop.

#Program 6-8
#Print even numbers in the given sequence
numbers = [1,2,3,4,5,6,7,8,9,10]
for num in numbers:
if (num % 2) == 0:
        print(num,’is an even Number’)

Output:
2 is an even Number
4 is an even Number
6 is an even Number
8 is an even Number
10 is an even Number

Flow of Control in Python Class 11 Notes

The Range() Function

The range() is a built-in function in Python. Syntax of range() function is:

range([start], stop[, step])

It is used to generate a list of integers with a difference equal to the specified step value that runs from the given start value to the specified stop value (excluding the stop value). The function range() is often used in for loops for generating a sequence of numbers.

#start and step not specified
>>> list(range(10)-)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
#default step value is 1
>>> list(range(2, 10))
[2, 3, 4, 5, 6, 7, 8, 9]
#step value is 5
>>> list(range(0, 30, 5))
[0, 5, 10, 15, 20, 25]
#step value is -1. Hence, decreasing
#sequence is generated
>>> range(0, -9, -1)
[0, -1, -2, -3, -4, -5, -6, -7, -8]

Q. Program to print the multiples of 10 for numbers in a given range.

#Program 6-9
#Print multiples of 10 for numbers in a given range
for num in range(5):
     if num > 0:
          print(num * 10)

Output:
10
20
30
40

Flow of Control in Python Class 11 Notes

The ‘While’ Loop

While a loop’s control condition is true, a block of code is continuously run using the while statement. The while loop’s control condition is carried out before any statements inside the loop are performed. The loop continues as long as the control condition is true after each iteration. The statements in the body of the loop are not performed while this condition is false, and instead, control is passed to the statement that follows the while loop’s body. The body is not even once run if the while loop’s initial condition is false.

Syntax of while Loop

while test_condition:
body of while

Q. Program to print first 5 natural numbers using while loop.

#Program 6-10
#Print first 5 natural numbers using while loop
count = 1
while count <= 5:
print(count)
count += 1

Output:
1
2
3
4
5

Q. Program to find the factors of a whole number using while loop.

#Program 6-11
#Find the factors of a number using while loop
num = int(input(“Enter a number to find its factor: “))
print (1, end=’ ‘) #1 is a factor of every number
factor = 2
while factor <= num/2 :
if num % factor == 0:
#the optional parameter end of print function specifies the delimeter
#blank space(‘ ‘) to print next value on same line
print(factor, end=’ ‘)
factor += 1
print (num, end=’ ‘) #every number is a factor of itself

Output:
Enter a number to find its factors : 6 1 2 3 6

Flow of Control in Python Class 11 Notes

Break and Continue Statement

Using looping techniques, programmers can efficiently repeat tasks. When a specific condition is met, there are times when we may want to end a loop (coming out of the loop indefinitely) or skip a few of its statements before proceeding. Use of break and continue statements, respectively, can satisfy these criteria. These statements are provided by Python as a tool to provide the programmer additional control over how a programme is executed.

Break Statement

The break statement modifies the normal course of execution by ending the current loop and continuing with the statement that follows it.

Q. Program to demonstrate use of break statement.

#Program 6-12
#Program to demonstrate the use of break statement in loop
num = 0
for num in range(10):
     num = num + 1
     if num == 8:
          break
     print(‘Num has value ‘ + str(num))
print(‘Encountered break!! Out of loop’)

Output:
Num has value 1
Num has value 2
Num has value 3
Num has value 4
Num has value 5
Num has value 6
Num has value 7
Encountered break!! Out of loop

Q. Find the sum of all the positive numbers entered by the user. As soon as the user enters a neagtive number, stop taking in any further input from the user and display the sum .

#Program 6-13
#Find the sum of all the positive numbers entered by the user
#till the user enters a negative number.
entry = 0
sum1 = 0
print(“Enter numbers to find their sum, negative number ends the
loop:”)
while True:
#int() typecasts string to integer
     entry = int(input())
     if (entry < 0):
         break
     sum1 += entry
print(“Sum =”, sum1)

Output:
Enter numbers to find their sum, negative number ends the loop:
3
4
5
-1
Sum = 12

Q. Program to check if the input number is prime or not.

#Program 6-14
#Write a Python program to check if a given number is prime or not.
num = int(input(“Enter the number to be checked: “))
flag = 0         #presume num is a prime number
if num > 1 :
     for i in range(2, int(num / 2)):
          if (num % i == 0):
               flag = 1        #num is a not prime number
               break       #no need to check any further
     if flag == 1:
          print(num , “is not a prime number”)
     else:
          print(num , “is a prime number”)
     else :
          print(“Entered number is <= 1, execute again!”)

Output 1:
     Enter the number to be checked: 20
     20 is not a prime number
Output 2:
     Enter the number to check: 19
    19 is a prime number
Output 3:
     Enter the number to check: 2
     2 is a prime number
Output 4:
    Enter the number to check: 1
    Entered number is <= 1, execute again!

Flow of Control in Python Class 11 Notes

Continue Statement

When a continue statement is found, the control goes to the beginning of the loop for the following iteration instead of executing any leftover statements in the loop’s body for the current iteration. The loop is restarted if the condition that initiated it is still true; else, control is passed to the statement that comes before the loop.

Q. Program to demonstrate the use of continue statement.

#Program 6-15
#Prints values from 0 to 6 except 3
num = 0
for num in range(6):
     num = num + 1
     if num == 3:
          continue
     print(‘Num has value ‘ + str(num))
print(‘End of loop’)

Output:
Num has value 1
Num has value 2
Num has value 4
Num has value 5
Num has value 6
End of loop

Flow of Control in Python Class 11 Notes

Nested Loops

A loop may contain another loop inside it. A loop inside another loop is called a nested loop. Python does not impose any restriction on how many loops can be nested inside a loop or on the levels of nesting. Any type of loop (for/while) may be nested within another loop (for/while).

Q. Program to demonstrate working of nested for loops.

#Program 6-16
#Demonstrate working of nested for loops
for var1 in range(3):
     print( “Iteration ” + str(var1 + 1) + ” of outer loop”)
     for var2 in range(2): #nested loop
         print(var2 + 1)
     print(“Out of inner loop”)
print(“Out of outer loop”)

Output:
Iteration 1 of outer loop
1
2
Out of inner loop
Iteration 2 of outer loop
1
2
Out of inner loop
Iteration 3 of outer loop
1
2
Out of inner loop
Out of outer loop

Q. Program to print the pattern for a number input by the user.

#Program 6-17
#Program to print the pattern for a number input by the user
#The output pattern to be generated is
#1
#1 2
#1 2 3
#1 2 3 4
#1 2 3 4 5
num = int(input(“Enter a number to generate its pattern = “))
for i in range(1,num + 1):
    for j in range(1,i + 1):
          print(j, end = ” “)
    print()

Output:
Enter a number to generate its pattern = 5
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Q. Program to find prime numbers between 2 to 50 using nested for loops.

#Program 6-18
#Use of nested loops to find the prime numbers between 2 to 50
num = 2
for i in range(2, 50):
     j= 2
     while ( j <= (i/2)):
          if (i % j == 0): #factor found
               break #break out of while loop
          j += 1
     if ( j > i/j) : #no factor found
          print ( i, “is a prime number”)
print (“Bye Bye!!”)

Output:
2 is a prime number
3 is a prime number
5 is a prime number
7 is a prime number
11 is a prime number
13 is a prime number
17 is a prime number
19 is a prime number
23 is a prime number
29 is a prime number
31 is a prime number
37 is a prime number
41 is a prime number
43 is a prime number
47 is a prime number
Bye Bye!!

Flow of Control in Python Class 11 Notes

Q. Write a program to calculate the factorial of a given number.

#Program 6-19
#The following program uses a for loop nested inside an if..else
#block to calculate the factorial of a given number
num = int(input(“Enter a number: “))
fact = 1
# check if the number is negative, positive or zero
if num < 0:
     print(“Sorry, factorial does not exist for negative numbers”)
elif num == 0:
     print(“The factorial of 0 is 1”)
else:
     for i in range(1, num + 1):
          fact = fact * i
     print(“factorial of “, num, ” is “, fact)

Output:
Enter a number: 5
Factorial of 5 is 120

Computer Science Class 11 Notes

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 MCQ

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 NCERT Solutions

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples and Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer

Teachers and Examiners (CBSESkillEduction) collaborated to create the Getting Started with Python Class 11 Notes. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Getting Started with Python Class 11 Notes

Python is a high-level, object-oriented programming language. Python is frequently considered as one of the simplest programming languages to learn for beginners. Python’s simple syntax prioritizes readability and makes it simple to learn, which lowers the cost of programme maintenance. Python’s support for modules and packages promotes the modularity and reuse of code in programmes. For all popular platforms, the Python interpreter and the comprehensive standard library are freely distributable and available in source or binary form.

Features of Python

• Python is a high-level language. It is a free and open-source language.
• It is an interpreted language, as Python programs are executed by an interpreter.
• Python programs are easy to understand as they have a clearly defined syntax and relatively simple structure.
• Python is case-sensitive. For example, NUMBER and number are not same in Python.
• Python is portable and platform independent, means it can run on various operating systems and hardware platforms.
• Python has a rich library of predefined functions.
• Python is also helpful in web development. Many popular web services and applications are built using Python.
• Python uses indentation for blocks and nested blocks.

Working with Python

We require a Python interpreter installed on our computer or we can utilise any online Python interpreter in order to create and run (execute) a Python programme. The Python shell is another name for the interpreter.
diagram

The Python prompt, represented by the symbol >>> in the screenshot above, indicates that the interpreter is prepared to accept commands.

Execution Modes

There are two ways to use the Python interpreter:
a) Interactive mode
b) Script mode

Interactive Mode

Programmers can quickly run the commands and try out or test code without generating a file by using the Python interactive mode, commonly known as the Python interpreter or Python shell. To work in the interactive mode, we can simply type a Python statement on the >>> prompt directly. It’s practical to test one line of code for immediate execution while working in interactive mode.

Script Mode

In the script mode, a Python programme can be written in a file, saved, and then run using the interpreter.
Python scripts are stored in files with the “.py” extension. Python scripts are saved by default in the Python installation folder.

Python Keywords

Keywords are reserved words. Each keyword has a specific meaning to the Python interpreter, and we can use a keyword in our program only for the purpose for which it has been defined. As Python is case sensitive, keywords must be written exactly.

Identifiers

Identifiers are names used in programming languages to identify a variable, function, or other things in a programme. Python has the following guidelines for naming an identifier:
a. The name should begin with an uppercase or a lowercase alphabet or an underscore sign (_).
b. It can be of any length.
c. It should not be a keyword or reserved word.
d. We cannot use special symbols like !, @, #, $, %, etc.

Variables

A variable’s name serves as a program’s unique identifier (identifier). In Python, the term “variable” refers to an object, which is a thing or things that is kept in memory. A variable’s value can be a string, such as “b,” or a number, such as “345,” or any combination of alphanumeric characters (CD67). In Python, we can create new variables and give them particular values by using an assignment statement.

gender = ‘M’
message = “Keep Smiling”
price = 987.9

Comments

In the source code, comments are used to add remarks or notes. The interpreter doesn’t carry out comments. They are included to make the source code simpler for individuals to understand. comments always start from #.

Example
#Add your python comments

Everything is an Object

Python treats every type of object, including variables, functions, lists, tuples, dictionaries, sets, etc., as an object. Each item belongs to a particular class. An integer variable, for instance, is a member of the integer class. An item is a physical thing. A collection of various data and functions that work with that data is an object.

Data Types

In Python, each value corresponds to a certain data type. A variable’s data type describes the kinds of data values it can store and the types of operations it can execute on that data. The data types that Python.

Number

Only numerical values are stored in the Number data type. Three other categories are used to further categories it: int, float, and complex.

diagram

Sequence

An ordered group of things, each of which is identified by an integer index, is referred to as a Python sequence. Strings, Lists, and Tuples are the three different forms of sequence data types that are available in Python.

1. String – A string is a collection of characters. These characters could be letters, numbers, or other special characters like spaces. Single or double quotation marks are used to surround string values for example, ‘Hello’ or “Hello”).
2. List – List is a sequence of items separated by commas and the items are enclosed in square brackets [ ]. example list1 = [5, 3.4, “New Delhi”, “20C”, 45]
3. Tuple – A tuple is a list of elements enclosed in parenthesis and separated by commas ( ). Compared to a list, where values are denoted by brackets [], this does not. We cannot alter the tuple once it has been formed. example tuple1 = (10, 20, “Apple”, 3.4, ‘a’)

Set

A set is a group of elements that are not necessarily in any particular order and are enclosed in curly brackets. The difference between a set and a list is that a set cannot include duplicate entries. A set’s components are fixed once it is constructed. examle set1 = {10,20,3.14,”New Delhi”}

None

A unique data type with only one value is called None. It is employed to denote a situation’s lack of worth. None is neither True nor False, and it does not support any special operations (zero). example myVar = None

Mapping

Python has an unordered data type called mapping. Python currently only supports the dictionary data type as a standard mapping data type.

1. Dictionary – Python’s dictionary stores data elements as key-value pairs. Curly brackets are used to surround words in dictionaries. Dictionary use enables quicker data access. example, dict1 = {‘Fruit’:’Apple’, ‘Climate’:’Cold’, ‘Price(kg)’:120}

Mutable and Immutable Data Types

Once a variable of a certain data type has been created and given values, Python does not enable us to modify its values. Mutable variables are those whose values can be modified after they have been created and assigned. Immutable variables are those whose values cannot be modified once they have been created and assigned.

Deciding Usage of Python Data Types

When we need a straightforward collection of data that can be modified frequently, lists are chosen.
For example, it is simple to update a list of student names when some new students enrol or some students drop out of a class. When there is no requirement for data modification, we use tuples. For instance, the names of the months of a year.

Operators

A specific mathematical or logical operation on values is performed using an operator. Operands are the values that the operators manipulate. As an illustration, the operands of the phrase 10 + num are the number 10 and the variable num, and the operator is the plus symbol (+).

Arithmetic Operators

The four fundamental arithmetic operations, as well as modular division, floor division, and exponentiation, are all supported by Python’s arithmetic operators.

Relational Operators

A relational operator establishes the relationship between the operands by comparing their values on either side.

Assignment Operators

Assignment operator assigns or changes the value of the variable on its left.

Logical Operators

Python is compatible with three logical operators. Only lower case letters may be used to write these operators (and, or, not).

Identity Operators

Identity operators are used to determine whether or not a variable’s value belongs to a particular type. To determine whether two variables are referring to the same object or not, identity operators can also be utilised. Two identity operators are available.

Membership Operators

Membership operators are used to check if a value is a member of the given sequence or not.

Expressions

A mixture of constants, variables, and operators is referred to as an expression. An expression will always yield a value. An expression can either be a value or a standalone variable, but a standalone operator is not an expression. Below are a few instances of legitimate expressions.

Precedence of Operators

The order in which an operator is applied in an expression where there are several types of operators is determined by its precedence. The operator with a higher precedence is evaluated before the operator with a lower precedence.

Statement

In Python, a statement is a unit of code that the Python interpreter can execute.

x = 4 #assignment statement
cube = x ** 3 #assignment statement
print (x, cube) #print statement
4 64

Input and Output

The user is prompted to provide data using the input() function. All user input is accepted as strings. Although the input() function only accepts strings, the user may enter either a number or a string. input() has the following syntax:

input ([Prompt])

Prompt is an optional string that we could choose to display on the screen before accepting input. When a prompt is specified, it is first shown to the user on the screen before data entry is allowed. The input() function accepts the text entered directly from the keyboard, turns it to a string, and then assigns it to the variable to the left of the assignment operator (=). Pressing the enter key ends data entry for the input function.

fname = input(“Enter your first name: “)
Enter your first name: Arnab
age = input(“Enter your age: “)
Enter your age: 19
type(age)

Python’s print() method outputs data to the screen, which is the standard output device. Before printing the expression, the print() function evaluates it.

Type Conversion

An object can be converted from one data type to another using typecasting, also known as type conversion. It is employed in computer programming to guarantee that a function processes variables appropriately. Converting an integer to a string is an illustration of typecasting. There are two type of conversion –

1. Explicit Conversion
2. Implicit Conversion

Explicit Conversion

Data type conversion that occurs because the programmer actively implemented it in the programme is referred to as explicit conversion, also known as type casting. An explicit data type conversion can take the following general forms:

(new_data_type) (expression)

Type Conversion between Numbers and Strings

priceIcecream = 25
priceBrownie = 45
totalPrice = priceIcecream + priceBrownie
print(“The total is Rs.” + totalPrice )

Implicit Conversion

When Python converts data types automatically without a programmer’s instruction, this is referred to as implicit conversion, also known as coercion.

Implicit type conversion from int to float

num1 = 10 #num1 is an integer
num2 = 20.0 #num2 is a float
sum1 = num1 + num2 #sum1 is sum of a float
and an integer
print(sum1)
print(type(sum1))

Debugging

A programmer’s errors can prevent a programme from running properly or from producing the intended results. Debugging is the process of finding and fixing these flaws, sometimes referred to as bugs or errors, in a software. Program errors can be categorised as follows:

1. Syntax errors
2. Logical errors
3. Runtime errors

Syntax Errors

The syntax of Python is determined by its own rules. Only correctly syntactical statements—those that adhere to Python’s rules—are interpreted by the interpreter. The interpreter displays any syntax errors and terminates the execution at that point. For example, parentheses must be in pairs, so the expression (10 + 12) is syntactically correct, whereas (7 + 11 is not due to absence of right parenthesis.

Logical Errors

A programme defect that results in improper behaviour is known as a logical error. A logical mistake results in an undesirable output without immediately stopping the program’s execution. It can be challenging to spot these issues because the programme interprets correctly even though it contains logical faults.

For example, if we wish to find the average of two numbers 10 and 12 and we write the code as 10 + 12/2, it would run successfully and produce the result 16. Surely, 16 is not the average of 10 and 12. The correct code to find the average should have been (10 + 12)/2 to give the correct output as 11.

Runtime Error

A runtime fault results in an unexpected programme termination while it is running. When a statement is syntactically correct but unable to be executed by the interpreter, it is said to have a runtime error. Runtime errors do not show up until the programme has begun to run or execute.

For example, we have a statement having division operation in the program. By mistake, if the denominator entered is zero then it will give a runtime error like “division by zero”.

Computer Science Class 11 Notes

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 MCQ

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 NCERT Solutions

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples and Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer

Teachers and Examiners (CBSESkillEduction) collaborated to create the Introduction to Problem Solving Class 11 Notes. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Introduction to Problem Solving Class 11 Notes

Introduction to Problem Solving

Problems cannot be resolved by computers alone. We must provide clear, step-by-step directions on how to solve the issue. Therefore, the effectiveness of a computer in solving a problem depends on how exactly and correctly we describe the problem, create an algorithm to solve it, and then use a programming language to implement the algorithm to create a programme. So, the process of identifying a problem, creating an algorithm to solve it, and then putting the method into practise to create a computer programme is known as problem solving.

Steps for Problem Solving

To identify the best solution to a difficult problem in a computer system, a Problem Solving methodical approach is necessary. To put it another way, we must use problem-solving strategies to solve the difficult problem in a computer system. Problem fixing starts with the accurate identification of the issue and concludes with a fully functional programme or software application.
Program Solving Steps are –
1. Analysing the problem
2. Developing an Algorithm
3. Coding
4. Testing and Debugging

Analyzing the problem – It is important to clearly understand a problem before we begin to find the solution for it. If we are not clear
as to what is to be solved, we may end up developing a program which may not solve our purpose.

Developing an Algorithm – Before creating the programme code to solve a particular problem, a solution must be thought out. Algorithm is a step by step process where we write the problem and the steps of the programs.

Coding – After the algorithm is completed, it must be translated into a form that the computer can understand in order to produce the desired outcome. A programme can be written in a number of high level programming languages.

Testing and Debugging – The developed programme needs to pass different parameter tests. The programme needs to fulfil the user’s requirements. It must answer in the anticipated amount of time. For all conceivable inputs, it must produce accurate output.

Introduction to Problem Solving Class 11 Notes

What is the purpose of Algorithm?

A programme is created by a programmer to tell the computer how to carry out specific activities. Then, the computer executes the instructions contained in the programme code. As a result, before creating any code, the programmer first creates a roadmap for the software. Without a roadmap, a programmer might not be able to visualise the instructions that need to be written clearly and might end up creating a software that might not function as intended. This roadmap is known as algorithm.

Why do we need an Algorithm?

A programme is created by a programmer to tell the computer how to carry out specific activities. Then, the computer executes the instructions contained in the programme code. As a result, before creating any code, the programmer first creates a roadmap for the software. Without a roadmap, a programmer might not be able to visualise the instructions that need to be written clearly and might end up creating a software that might not function as intended. This roadmap is known as algorithm.

The purpose of using an algorithm is to increase the reliability, accuracy and efficiency of obtaining solutions.

Characteristics of a good algorithm

• Precision — the steps are precisely stated or defined.
• Uniqueness — results of each step are uniquely defined and only depend on the input and the result of the preceding steps.
• Finiteness — the algorithm always stops after a finite number of steps.
• Input — the algorithm receives some input.
• Output — the algorithm produces some output.

While writing an algorithm, it is required to clearly identify the following:

• The input to be taken from the user
• Processing or computation to be performed to get the desired result
• The output desired by the user

Introduction to Problem Solving Class 11 Notes

Representation of Algorithms

There are two common methods of representing an algorithm —flowchart and pseudocode. Either of the methods can be used to represent an algorithm while keeping in mind the following:
• it showcases the logic of the problem solution, excluding any implementational details
• it clearly reveals the flow of control during execution of the program

Flowchart — Visual Representation of Algorithms

A flowchart is a visual representation of an algorithm. A flowchart is a diagram made up of boxes, diamonds and other shapes, connected by arrows. Each shape represents a step of the solution process and the arrow represents the order or link among the steps.

There are standardized symbols to draw flowcharts. Some are given below –

Flow Chart Syntax

Introduction to Problem Solving Class 11 Notes

How to draw flowchart

Q. Draw a flowchart to find the sum of two numbers?

Q. Draw a flowchart to print the number from 1 to 10?

Introduction to Problem Solving Class 11 Notes

Pseudocode

Another way to represent an algorithm is with a pseudocode, which is pronounced Soo-doh-kohd. It is regarded as a non-formal language that aids in the creation of algorithms by programmers. It is a thorough explanation of the steps a computer must take in a specific order.

The word “pseudo” means “not real,” so “pseudocode” means “not real code”. Following are some of the frequently used keywords while writing pseudocode –

• INPUT
• COMPUTE
• PRINT
• INCREMENT
• DECREMENT
• IF/ELSE
• WHILE
• TRUE/FALSE

Example

Write an algorithm to display the sum of two numbers entered by user, using both pseudocode and flowchart.

Pseudocode for the sum of two numbers will be –
input num1
input num2
COMPUTE Result = num1 + num2
PRINT Result

Flowchart for this pseudocode or algorithm –

Introduction to Problem Solving Class 11 Notes

Flow of Control

The flow of control depicts the flow of events as represented in the flow chart. The events can flow in a sequence, or on branch based on a decision or even repeat some part for a finite number of times.

Sequence – These algorithms are referred to as executing in sequence when each step is carried out one after the other.

Selection – An algorithm may require a question at some point because it has come to a stage when one or more options are available. This type of problem we can solve using If Statement and Switch Statement in algorithm or in the program.

Repetition – We often use phrases like “go 50 steps then turn right” while giving directions. or “Walk to the next intersection and turn right.” These are the kind of statements we use, when we want something to be done repeatedly.  This type of problem we can solve using For Statement, While and do-while statement.

Verifying Algorithms

Software is now used in even more important services, such as the medical industry and space missions. Such software must function properly in any circumstance. As a result, the software designer must ensure that every component’s operation is accurately defined, validated, and confirmed in every way.

To verify, we must use several input values and run the algorithm for each one to produce the desired result. We can then tweak or enhance the algorithm as necessary.

Comparison of Algorithm

There may be more than one method to use a computer to solve a problem, If you wish to compare two programmes that were created using two different approaches for resolving the same issue, they should both have been built using the same compiler and executed on the same machine under identical circumstances.

Introduction to Problem Solving Class 11 Notes

Coding

Once an algorithm is decided upon, it should be written in the high-level programming language of the programmer’s choice. By adhering to its grammar, the ordered collection of instructions is written in that programming language.
The grammar or set of rules known as syntax controls how sentences are produced in a language, including word order, punctuation, and spelling.

Decomposition

A problem may occasionally be complex, meaning that its solution cannot always be found. In these circumstances, we must break it down into simpler components. Decomposing or breaking down a complicated problem into smaller subproblems is the fundamental concept behind addressing a complex problem by decomposition. These side issues are more straightforward to resolve than the main issue.

Computer Science Class 11 Notes

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 MCQ

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 NCERT Solutions

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples and Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer

Teachers and Examiners (CBSESkillEduction) collaborated to create the Emerging Trends Class 11 Notes. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Emerging Trends Class 11 Notes

Artificial Intelligence (AI)

Artificial intelligence, or I, refers to devices or programmes that resemble human intelligence in order to carry out tasks and have the ability to iteratively improve themselves based on the data they gather.

Artificial intelligence aims to imitate human intelligence naturally in machines so that they will act intelligently. An intelligent machine should be able to mimic some of the cognitive processes that people use to learn, make decisions, and solve problems. Machines are trained to build a knowledge base and base judgments off of it in order to complete jobs with the least amount of human involvement. In order to make new judgments, AI systems can also learn from their prior actions or results.

Machine Learning

Machine learning is a branch of artificial intelligence that enables computers to learn from data using statistical methods without explicit human programming. It includes algorithms that use information to learn on their own and anticipate the future.

Natural Language Processing (NLP)

Natural Language Processing (NLP) It deals with how people and computers communicate using human spoken languages like Hindi, English, etc. In fact, using our voice to conduct a web search, use a device, or control another device is achievable. NLP has made all of this feasible. An NLP system can convert speech to text and text to speech.

Emerging Trends Class 11 Notes

Immersive Experiences

Now movies are three dimension, video games are also begin developed to provide immersive experiences to the player. Immersive experiences allow us to visualize, feel and react by stimulating our senses. It enhances our interaction and involvement, making them more realistic and engaging. Immersive experiences have been used in the field of training, such as driving simulators , flight simulator and so on.

Virtual Reality – Virtual Reality (VR) is a three-dimensional, computer-generated situation that simulates the real world. The user can interact with and explore that environment by getting immersed in it while interacting with the objects and other actions of the user.

Augmented Reality – The term “augmented reality” refers to the superimposition of computer-generated perceptual information over the actual physical surroundings (AR). Consider Pokémon Go as an illustration, where players look for animated characters that appear in their real-world surroundings on their phone or tablet.

Emerging Trends Class 11 Notes

Robotics

A robot is essentially a machine that can complete one or more activities accurately and precisely on its own. A robot is programmable by a computer, which implies it can obey commands supplied by computer programmes, unlike other devices.

1. Mars Exploration Rover (MER) is a robotic space mission launched by NASA to learn more about the planet Mars.
2. Sophia is a humanoid robot that mimics human movements and facial expressions and uses artificial intelligence, visual data processing, and facial recognition.
3. An unmanned aircraft called a drone can be remotely piloted or can fly on its own using software-controlled flight plans in embedded systems in conjunction with onboard sensors and GPS.

Emerging Trends Class 11 Notes

Big Data

Every day, over 2.5 quintillion bytes of data are generated, and the rate is rising due to the Internet of Things’ ongoing development (IoT). As a result, big data—data sets with a large volume and high level of complexity—are created.

Such data cannot be handled and analyzed using conventional data processing methods because it is not only large but also unstructured, such as our posts, conversations, and instant messages, as well as the pictures. This data is highly valuable in the businesses, So, there is a strong focus on developing tools and processes to process and analyze big data.

Characteristics of Big Data

There are five different types of characteristics of Big Data – 

1. Volume – Size presents the biggest challenge for large data. It will be challenging to process a certain dataset if it is large.
2. Velocity – Velocity is the term used to describe the speed with which information must be processed after being input into a system. For example, Amazon record every click of the mouse when the shoppers are browsing on its website.
3. Variety – All the organized and unstructured data that could be produced by either people or machines is referred to as variety in big data.
4. Veracity – Big data can occasionally be inaccurate, distorted, noisy, or contain errors. It can also have problems with the methods used to obtain the data. Veracity relates to how reliable the data is.
5. Value – Big data is more than just a large collection of data; it also contains hidden patterns and insightful information that may be highly valuable to businesses.

Emerging Trends Class 11 Notes

Data Analytics

The practise of analysing datasets to make judgments about the information they contain is known as data analytics. You can take raw data and use data analytical tools to find patterns and gain insightful conclusions from it.

“Data analytics is the process of examining data sets in order to draw conclusions about the information they contain, with the aid of specialised systems and software.”

Internet of Things (IoT)

The “Internet of Things” is a collection of interconnected devices that can connect to one another and exchange data in the same network or you can say, It is a overall network of interconnected devices as well as the technology that enables communication between them.

Web of Things (WoT)

Internet of Things allows us to interact with different devices through Internet with the help of smartphones or computers, Web of Things (WoT) allows use of web services to connect anything in the physical world, besides human identities on web. It will pave way for creating smart homes, smart offices, smart cities and so on.

Emerging Trends Class 11 Notes

Sensors

Sensors are frequently used as monitoring and observing components. The development of IoT is being greatly aided by the evolution of smart electronic sensors. It will result in the development of fresh, intelligent systems with sensors.
A smart sensor is a device that receives input from the physical world and uses internal computer power to carry out predetermined tasks when a certain input is detected. The data is then processed before being transmitted.

Smart Cities

A smart city use the information and communication technologies (ICT), for creating, implementing, and promoting sustainable development methods to handle the issues of expanding urbanisation. Smart City handle transportation
systems, power plants, water supply networks, waste management, law enforcement, information systems, schools, libraries, hospitals and other community services work in unison to optimise the efficiency of city operations and services through the information and communication technologies.

Cloud Computing

Cloud computing is a new trend where computer-based services are supplied via the Internet or the cloud and are accessible to the user from any location using any device. Cloud computing is the distribution of computer services over the Internet (“the cloud”), including servers, storage, databases, networking, software, analytics, and intelligence.

Cloud Services

There are three standard models to categories different computing services delivered through cloud –

1. Infrastructure as a Service (IaaS)
2. Platform as a Service (PaaS)
3. Software as a Service (SaaS)

Infrastructure as a Service (IaaS) – IaaS is a particular kind of cloud computing service that provides necessary computation, storage, and networking resources on demand for example different types of computer infrastructure, such as servers, virtual machines (VM), storage and backup facilities, network components, operating systems, or any other hardware or software, can be offered by IaaS providers.

Platform as a Service (PaaS) – a cloud-based service that enables users to install and run applications without worrying about their setup or underlying infrastructure. In other words, PaaS offers a platform or setting for creating, testing, and distributing software applications.

Software as a Service (SaaS) – SaaS offers on-demand access to application software; often, this service requires user licencing or subscription. We utilise SaaS from the cloud when using Google Doc, Microsoft Office 365, Drop Box, etc. to modify a document online.

Emerging Trends Class 11 Notes

Grid Computing

Grid computing refers to a network of computers from various administrative domains cooperating to complete a task. Grid computing enables simple completion of complicated tasks that may be intractable for a single computer machine.

Grid can be of two types —

1. Data grid, used to manage large and distributed data having required multi-user access, and
2. CPU or Processor grid, where processing is moved from one PC to another as needed or a large task is divided into subtasks and divided to various nodes for parallel processing.

Blockchains

The blockchain technology is based on the idea of a shared, decentralised database that is replicated on every computer. A block is a safeguarded section of data or a legitimate transaction. Only the block’s owner has access to the block’s private data, which is hidden behind the header of each block, which is visible to all other nodes. These blocks come together to form the blockchain.

Teachers and Examiners (CBSESkillEduction) collaborated to create the Encoding Schemes and Number System Class 11 Notes. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Encoding Schemes and Number System Class 11 Notes

Encoding Schemes

A computer can only understand binary (0s and 1s) numbers. As a result, whenever a key is touched on a keyboard, is internally translated into a special code known as unique code and then converted to binary. for example, Pressing the key “A” causes is internally mapped to the value 65 (the code value), which is then translated to its corresponding binary value for the computer to comprehend. encoding helps the system to give unique number to the characters, symbols or numbers. 

What is encoding?

Encoding is the process of transforming data into an encryption process that is equivalent using a particular code. Some of the well-known encoding schemes are described in the following sections. There are three most popular encoding in computer system.
a. American Standard Code for Information Interchange (ASCII)
b. Indian Script Code for Information Interchange (ISCII)
c. Unicode ( Most popular coding method)

American Standard Code for Information Interchange (ASCII)

For the purpose of standardizing character representation, ASCII was created. The most widely used coding technique is still ASCII. ASCII represented characters using 7 bits. There are just 2 binary digits 0 and 1. Consequently, the total amount of distinct characters on the 27 = 128 on an English keyboard can be represented by a 7-bit ASCII code.

Encoding Schemes and Number System Class 11 Notes

Indian Script Code for Information Interchange (ISCII)

A standard for coding Indian scripts it is develop in the middle of the 1980s, India developed a system of characters known as ISCII. It is an 8-bit representation of Indian languages. which means it can represent 28=256 characters.

Unicode

Every character in the Unicode Standard has a specific number, independent of the platform, gadget, programme, or language. As a result of its wider adoption by modern software vendors, data may now be sent without corruption across a wide range of platforms, gadgets, and programmes.

The most popular method for identifying characters in text in almost any language is now Unicode. Unicode uses three different encoding formats: 8-bit, 16-bit, and 32-bit.

Encoding Schemes and Number System Class 11 Notes

Number System

What is Number System?

A way to represent (write) numbers is called a number system. There are a specific set of characters or literals for each number system. It is the mathematical notation for consistently employing digits or other symbols to represent the numbers in a particular set.
There are four different types of number system
a. Decimal Number System
b. Binary Number
c. Hexadecimal Number
d. Octal Number

Encoding Schemes and Number System Class 11 Notes

Decimal Number System

Decimal is single digit number system in computer. The decimal number system consists of ten single-digit numbers 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. This number system is also known as based-10 number.

Binary Number System

Binary Number is used in computer system because computer only understands the language of the two digits 0 and 1 (low/high). Binary number is also known as the base-2 system. Examples of binary numbers include 111111.01, 1011101, and 1001011.

Encoding Schemes and Number System Class 11 Notes

Octal Number System

Sometimes, a binary number is so large that it becomes difficult to manage. Octal number system was devised for compact representation of the binary numbers. Octal number system is called base-8 system.

Hexadecimal Number System

Hexadecimal numbers are also used for compact representation of binary numbers. It consists of 16 unique symbols (0–9, A–F), and is called base16 system. In hexadecimal system, each alphanumeric digit is represented as a group of 4 binary digits because 4 bits (24=16) are sufficient to represent 16 alphanumeric symbols.

Encoding Schemes and Number System Class 11 Notes

Applications of Hexadecimal Number System

Every byte’s memory location is described using the hexadecimal number system. For computer professionals, these hexadecimal numbers are also simpler to read and write than binary or decimal numbers.

Memory Address example using hexadecimal Number System

Color code example using hexadecimal Number System

Conversion between Number Systems

Although digital computers understand binary numbers, humans most often utilise the decimal number system. Octal and hexadecimal number systems are used to make the binary representation easier for us to understand. Lets see some of the number conversion system –

Conversion from Decimal to other Number Systems

To convert a decimal number to any other number system (binary, octal or hexadecimal), use the steps
given below.
Step 1: Divide the given number by the base value (b) of the number system in which it is to be converted
Step 2: Note the remainder
Step 3: Keep on dividing the quotient by the base value and note the remainder till the quotient is zero
Step 4: Write the noted remainders in the reverse order (from bottom to top)

Encoding Schemes and Number System Class 11 Notes

Decimal to Binary Conversion

Binary equivalent of 65 is (1000001)₂. Let us now convert a decimal value to its binary representation and verify that the binary equivalent of (65)₁₀ is (1000001)₂.

Decimal to Octal Conversion

Since the base value of octal is 8, the decimal number is repeatedly divided by 8 to obtain its equivalent octal number. The octal equivalent of letter “A” by using its ASCII code value (65)₁₀ is calculated in below figure –

Decimal to Hexadecimal Conversion

Since the base value of hexadecimal is 16, the decimal number is repeatedly divided by 16 to obtain its equivalent hexadecimal number. The hexadecimal equivalent of letter ‘A’ using its ASCII code (65)₁₀ is calculated as shown below –

Conversion from other Number Systems to Decimal Number System

We can use the following steps to convert the given number with base value b to its decimal equivalent, where base value b can be 2, 8 and 16 for binary, octal and hexadecimal number system, respectively.

Step 1: Write the position number for each alphanumeric symbol in the given number
Step 2: Get positional value for each symbol by raising its position number to the base value b symbol in the given number
Step 3: Multiply each digit with the respective positional value to get a decimal value
Step 4: Add all these decimal values to get the equivalent decimal number

Encoding Schemes and Number System Class 11 Notes

Binary Number to Decimal Number

Binary number system has base 2, the positional values are computed in terms of powers of 2. Using the above mentioned steps we can convert a binary number to its equivalent decimal value as shown below –

Octal Number to Decimal Number

The following example shows how to compute the decimal equivalent of an octal number using base value 8.

Hexadecimal Number to Decimal Number

For converting a hexadecimal number into decimal number, use steps given in this section with base value 16 of hexadecimal number system. Use decimal value equivalent to alphabet symbol of hexadecimal number in the calculation, as shown below –

Computer Science Class 11 Notes

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 MCQ

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 NCERT Solutions

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples and Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer

Teachers and Examiners (CBSESkillEduction) collaborated to create the Computer System Class 11 MCQ. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Computer System Class 11 MCQ

1. A computer along with additional hardware and software together is called a ___________.
a. Device System
b. Computer System 
c. Electronic System
d. None of the above

2. CPU is the electronic circuitry of a computer that carries out the actual processing and usually referred to as the ___________ of the computer.
a. Heart
b. Brain 
c. Head
d. None of the above

3. Physically, a CPU can be placed on one or more microchips called ____________.
a. integrated circuits (IC) 
b. Capacitor
c. Transistor
d. None of the above

4. The CPU is given instructions and data through programs. The CPU then fetches the program and data from the memory and performs _______________ as per the given instructions and stores the result back to memory.
a. Logical Operation
b. Arithmetic Operation
c. Arithmetic and Logic operations 
d. None of the above

5. While processing, the CPU stores the data as well as instructions in its local memory called __________.
a. Registers 
b. Gate
c. Catch
d. None of the above

6. CPU is also known as _____________.
a. Microprocessor 
b. Gate
c. Catch
d. None of the above

7. _____________ controls sequential instruction execution, interprets instructions and guides data flow through the computer’s memory.
a. Control Unit 
b. Arithmetic Logical Unit
c. Memory Unit
d. None of the above

8. The devices through which control signals are sent to a computer are termed as __________.
a. Output Device
b. Input Device 
c. Process
d. None of the above

9. Data entered through the input device is temporarily stored in the __________ of the computer system.
a. Read only memory
b. Random Access Memory 
c. Secondary Memory
d. None of the above

10. The device that receives data from a computer system for display, physical production, etc., is called _________.
a. Output Device 
b. Input Device
c. Process
d. None of the above

11. _________ printer used to build physical replica of digital 3D design (It is used to create prototypes).
a. LaserJet
b. Inkjet
c. Dot-Matrix
d. 3D-Printer 

12. Blaize Pascal invented a mechanical calculator known as ____________.
a. Tabulating Machine
b. Pascaline 
c. Analytic Engine
d. None of the above

13. Charles Babbage invented __________ mechanical computing device for inputting, processing, storing and displaying the output.
a. Tabulating Machine
b. Pascaline
c. Analytic Engine 
d. None of the above

14. __________ is known as the father of computers.
a. Blaize Pascale
b. Charles Babbage 
c. Herman Hollerith
d. None of the above

15. ______ was created 3000 years ago, and it is capable of performing basic arithmetic operations.
a. Analytic Engine
b. Abacus 
c. Turing Machine
d. Tabulating Machine

16. John Von Neumann invented a ____________ machine that can store both programmes and data in memory.
a. EDVAC
b. ENIAC
c. Both a) and b) 
d. None of the above

17. __________ is a silicon chip which contains an entire electronic circuit on a very small area and helps to reduce the size of the computer.
a. Vacuum Tubes
b. Integrated Circuit 
c. Transistor
d. None of the above

18. ____________ architecture having a central processing unit, memory to store data and program, input and output devices and communication channels to send or receive the output data.
a. Von Neumann Architecture 
b. Blaize Pascal Architecture
c. Herman Hollerith Architecture
d. Charles Babbage Architecture

19. ENIAC Stands for __________.
a. Electric Numerical Interpreter and Calculator
b. Electronic Numerical Integrator and Computer 
c. Electric Numerical Integrator and Calculator
d. None of the above

20. Which architecture is based on a binary program.
a. Von Neumann Architecture 
b. Blaize Pascal Architecture
c. Herman Hollerith Architecture
d. Charles Babbage Architecture

21. During the 1970s, Large Scale Integration (LSI) of electronic circuits allowed integration of complete CPUs on a single chip, called ______________.
a. Silicon Chip
b. Microprocessor 
c. Microcomputer
d. None of the above

22. VLSI Stands for ___________.
a. Very Large Scale Integration 
b. Very Last Scale Integration
c. Very Large Small Integration
d. None of the above

23. With further technological improvement, it is now possible to create an integrated circuit (IC) with a high density of transistors and other components (about 106 components). This process is known as _____________.
a. Very Large Scale Integration
b. Super Large Scale Integration 
c. Small Scale Integration
d. None of the above

24. IBM introduced its first personal computer in the year of ________.
a. 1971
b. 1975
c. 1981 
d. 1985

25. Apple introduced Macintosh machines in __________.
a. 1971
b. 1975
c. 1980
d. 1984 

26. _____________ operating system based on command line interface.
a. UNIX
b. DOS
c. Both a) and b) 
d. None of the above

27. WWW stands for ___________.
a. World Wide Web 
b. World Widest Web
c. World Web Wide
d. None of the above

28. The device that can link to other systems and devices via the Internet or other communication networks and exchange data with them is known as ____________.
a. Internet of Web (IoW)
b. Internet of Things (IoT) 
c. Internet of Intelligence (IoI)
d. None of the above

29. The binary digits 0 and 1, which are the basic units of memory, are called __________.
a. Bytes
b. Nibble
c. Bite 
d. None of the above

30. The 4-bit word is called a _________.
a. Bytes
b. Nibble 
c. Bite
d. None of the above

31. 1KB = ___________.
a. 1024 Bytes 
b. 1024 KB
c. 1024 MB
d. None of the above

32. 1 TB = _________.
a. 1024 KB
b. 1024 MB
c. 1024 GB 
d. None of the above

33. __________ is a volatile memory.
a. RAM 
b. ROM
c. CPU
d. None of the above

34. RAM stands for ___________.
a. Random Applicable Memory
b. Random Access Memory 
c. Random Acceptable Memory
d. None of the above

35. RAM and ROM is usually referred to as __________.
a. Secondary Memory
b. Main Memory
c. Primary Memory
d. Both b) and c) 

36. To speed up the operations of the CPU, a very high speed memory is placed between the CPU and the primary memory known as ___________.
a. Secondary Memory
b. Primary Memory
c. Cache Memory 
d. Main Memory

37. Examples of secondary memory devices include ____________.
a. Hard Disk
b. Compact Disk
c. Pen Drive
d. All of the above 

38. Data is transferred between different components of a computer system using physical wires called _________.
a. Data Bus 
b. Cache Memory
c. Secondary Memory
d. Primary Memory

39. Which one of the following is a member of System Bus.
a. Data Bus
b. Address Bus
c. Control Bus
d. All of the above 

40. Data Bus sends the data __________, and Address Bus sends the address __________.
a. Bidirectional, Unidirectional 
b. Bidirectional, Bidirectional
c. Unidirectional, Unidirectional
d. Unidirectional, Bibirectional

41. ____________ is a small-sized electronic component inside a computer that carries out various tasks involved in data processing as well as arithmetic and logical operations.
a. Microchip
b. Microprocessor 
c. Main Chip
d. None of the above

42. Examples of fifth generations of microprocessors are ___________.
a. Pentium
b. Celeron
c. Xeon
d. All of the above 

43. Microprocessors are classified on the basis of different features which include ___________.
a. Word Size
b. Memory Size
c. Clock Speed
d. All of the above 

44. Word size is the maximum number of bits that a microprocessor can process at a time, now the maximum word size is __________ bits.
a. 8 Bits
b. 16 Bits
c. 32 Bits
d. 64 Bits 

45. The _____________ indicates the speed at which the computer can execute instructions.
a. Core
b. Memory Size
c. Clock Speed 
d. None of the above

46. Microprocessor having a basic computation unit is known as ___________.
a. Core 
b. Clock Speed
c. Memory Size
d. None of the above

47. The ___________ is a small computing device which has a CPU, a fixed amount of RAM, ROM and other peripherals all embedded on a single chip.
a. Microprocessor
b. Microchip
c. Microcontroller 
d. None of the above

48. Which of the following computers considers as data ____________.
a. Picture
b. Songs & Video
c. Document
d. All of the above 

49. A computer system has many input devices, which provide it with raw data in the form of ____________.
a. Facts
b. Concepts
c. Instructions
d. All of the above 

50. Data which follows a strict record structure and is easy to comprehend is called __________.
a. Structured Data 
b. Unstructured Data
c. Semi-structured Data
d. None of the above

51. Data which is not organized in a predefined record format is called ___________.
a. Structured Data
b. Unstructured Data 
c. Semi-structured Data
d. None of the above

52. Data which have no well-defined structure but maintain internal tags or markings to separate data elements are called ____________.
a. Structured Data
b. Unstructured Data
c. Semi-structured Data 
d. None of the above

53. The software that provides the basic functionality to operate a computer by interacting directly with its constituent hardware is termed as ___________.
a. System Software 
b. Programming tools
c. Application Software
d. None of the above

54. An ___________ is the most basic system software, without which other software cannot work.
a. System Software
b. Programming tools
c. Application Software
d. Operating System 

55. Software used for maintenance and configuration of the computer system is called ___________.
a. System Software
b. Programming tools
c. System Utilities 
d. Operating System

56. The ___________ acts as an interface between the device and the operating system.
a. Device Driver 
b. Programming tools
c. System Utilities
d. Operating System

57. In computers it is very difficult for a human being to write instructions in the form of __________.
a. High level language
b. Low level language
c. 1s and 0s 
d. All of the above

58. ____________ are machine dependent languages and include machine language and assembly language.
a. Low level language 
b. High level language
c. 4th Generation language
d. None of the above

59. Machine language uses _________ to write instructions which are directly understood and executed by the computer.
a. High level language
b. Low level language
c. 1s and 0s 
d. All of the above

60. Example of High level language.
a. C++
b. Java
c. Python
d. All of the above 

61. a __________ is needed to convert a program written in assembly or high level language to machine language.
a. Language Reader
b. Language Translator 
c. Language Coder
d. None of the above

62. The program code written in assembly or high-level language is called __________.
a. Program code
b. Source code 
c. Text code
d. None of the above

63. Example of translator in computer system.
a. Assembler
b. Compiler
c. Interpreter
d. All of the above 

64. The translator used to convert the code written in assembly language to machine language is called ________.
a. Assembler 
b. Compiler
c. Interpreter
d. All of the above

65. __________ translator takes one line, converts it into executable code if the line is syntactically correct, and then it repeats these steps for all lines in the source code.
a. Assembler
b. Compiler
c. Interpreter 
d. All of the above

66. The application software developed for generic applications, to cater to a bigger audience in general are called __________.
a. Customized Software
b. General Purpose Software 
c. Both a) and b)
d. None of the above

67. Examples of general purpose software are __________.
a. LibreOffice
b. GIMP
c. Mozilla or Chrome
d. All of the above 

68. These are custom or tailor-made application software, that are developed to meet the requirements of a specific organization or an individual is known as _________.
a. General Purpose Software
b. Customized Software 
c. Digital Software
d. None of the above

69. Examples of customized software are ____________.
a. School Management Software
b. Accounting Software
c. User-defined Software
d. All of the above 

70. The developers of some application software provide their source code as well as the software freely to the public, with an aim to develop and improve further with each other’s help this type of software is known as _________.
a. Free Software
b. Open Source Software
c. Both a) and b) 
d. None of the above

71. Examples of open source software in computer systems are _________.
a. Libreoffice
b. Python
c. Mozilla Firefox
d. All of the above 

72. Some of the software is freely available for use but source code may not be available, such software is called _________.
a. Open Source Software
b. Freeware Software 
c. Both a) and b)
d. None of the above

73. An __________ can be considered to be a resource manager which manages all the resources of a computer.
a. Operating System 
b. Application Program
c. Open Source
d. All of the above

74. The primary objectives of an operating system are __________.
a. Two-fold
b. Interface to the user
c. Both a) and b) 
d. None of the above

75. ____________ is often less interactive and usually allows a user to run a single program at a time.
a. Command-based Interface 
b. Graphical User Interface
c. Both a) and b)
d. None of the above

76. Example of command-based interface operating system.
a. Ms-Dos
b. Unix
c. Both a) and b) 
d. None of the above

77. ____________run programs or give instructions to the computer in the form of icons, menus and other visual options.
a. Command-based Interface
b. Graphical User Interface 
c. Both a) and b)
d. None of the above

78. Example of graphical user-interface.
a. Windows Operating System
b. Ubuntu Operating System
c. Macintosh Operating System
d. All of the above 

79. _________ interface allows users to interact with the system simply using the touch input.
a. Command-based Interface
b. Graphical User Interface
c. Touch-based Interface 
d. None of the above

80. __________ interface helps people with special needs and people who want to interact with computers or smartphones while doing some other task.
a. Command-based Interface
b. Graphical User Interface
c. Touch-based Interface
d. Voice-based Interface 

81. Example of Voice-based Interface.
a. iOS (Siri)
b. OK Google or Google Now
c. Windows 10 (Cortana)
d. All of the above 

82. __________ interface interacts with the device using waving, tilting, eye motion and shaking.
a. Gesture-based Interface 
b. Graphical User Interface
c. Touch-based Interface
d. Voice-based Interface

83. ___________ concerns the management of multiple processes, allocation of required resources, and exchange of information among processes.
a. Process Management 
b. Memory Management
c. File Management
d. Device Management

84. ___________ concerns with management of main memory so that maximum memory is occupied or utilized by a large number of processes while keeping track of each and every location within the memory as free or occupied.
a. Process Management
b. Memory Management 
c. File Management
d. Device Management

85. File management system manages secondary memory, while a memory management system handles the main memory of a computer system.
a. Process Management
b. Memory Management
c. File Management 
d. Device Management

Computer Science Class 11 Notes

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 MCQ

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 NCERT Solutions

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples and Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer

Teachers and Examiners (CBSESkillEduction) collaborated to create the Computer System Class 11 Notes. All the important Information are taken from the NCERT Textbook Computer Science (083) class 11.

Computer System Class 11 Notes

Introduction to Computer System

A computer is an electronic device that can be programmed to accept data (input), process it and generate result (output).

A computer system’s main components include a central input/output devices, memory, and the processor unit (CPU). and storage mechanisms. Each of these parts is functional. together to produce the desired result as a single unit.

Central Processing Unit (CPU)

All instructions that a computer’s hardware and software send to it are handled by the CPU. The Arithmetic Logic Unit (ALU) and the Control Unit are the two fundamental parts of the CPU. ALU does all necessary arithmetic and logical operations in accordance with programme instructions.

Input Devices

Input devices are the devices used to transmit control signals to a computer. These tools transform the input data into a digital format that the computer system can use. Example – Keyboard, Mouse, Scanner, Microphone etc.

Output Devices

An output device is a device that receives data from a computer system for display to the users. Output device  transforms digital data into forms that people can understand. Example – Monitor, Speaker, Projector, Headphone etc.

Evolution of Computer

1. 500 BC (Abacus) – Computing is attributed to the invention of ABACUS almost 3000 years ago. It was a mechanical device capable of doing simple arithmetic calculations only.
2. 1942 (Pasealine) – Blaize Pascal created the Pascaline, a mechanical calculator that does multiplication and division by repeatedly adding and subtracting two numbers, as well as direct addition and subtraction of two numbers.
3. 1834 (Analytic Engine) – Charles Babbage invented analytical engine, a mechanical computing device for inputting, processing, storing and displaying the output, which is considered to form the basis of modern computers.
4. 1890 (Tabulating Machine) – A tabulating device was created by Herman Hollerith to summarise the information on the punched card. It is regarded as the beginning of programming.
5. 1937 (Turing Machine) – Turing’s machine that could solve any problem by running the code written on punched cards was known as a general-purpose, programmable machine (GPPC).
6. 1945 (EDVAC/ENIAC) – The idea of a stored programme computer, which could store both programmes and data in memory, was first proposed by John Von Neumann. Based on this idea, the EDVAC and later the ENIAC computers were created.
7. 1947 (Transistor) – Vacuum tubes were replaced by transistors developed at Bell Labs, using semiconductor materials.
8. 1970 (Integrated Circuit) – A silicon chip called an integrated circuit (IC) has a whole electronic circuit on a relatively small surface. ICs significantly reduced the size of the computer.

Von Neumann architecture for the computer

The central processing unit (CPU), often known as a processor or core, the main memory, and a connection between the memory and the CPU make up the von Neumann architecture. Each of the regions that make up main memory is able to store both data and instructions.

Computer Memory

A computer system needs memory to store the data and instructions for processing.

Units of Memory

Binary numbers are used by computers to store and process data. Bits refer to the fundamental building blocks of memory, the binary digits 0 and 1. These pieces are also combined to create words. A Nibble is an 8-bit word.

• KB (Kilobyte) 1 KB = 1024 Bytes
• MB (Megabyte) 1 MB = 1024 KB
• GB (Gigabyte) 1 GB = 1024 MB
• TB (Terabyte) 1 TB = 1024 GB
• PB (Petabyte) 1 PB = 1024 TB
• EB (Exabyte) 1 EB = 1024 PB
• ZB (Zettabyte) 1 ZB = 1024 EB
• YB (Yottabyte) 1 YB = 1024 ZB

Types of Memory

Computers have two types of memory — primary and secondary.

Primary Memory – The area of the computer where current data, programmes, and instructions are stored is referred to as primary memory or main memory. Because the primary memory is located on the motherboard, data from the primary memory may be read and written very quickly. Primary memory have two types

1. Random Access Memory (RAM) and
2. Read Only Memory (ROM).

Cache Memory – RAM is faster than secondary storage, but not as fast as a computer processor. So, because of RAM, a CPU may have to slow down. To speed up the operations of the CPU, a very high speed memory is placed between the CPU and the primary memory known as cache.

Secondary Memory – secondary memory to permanently store the data or instructions for future use. The secondary memory is non-volatile and has larger storage capacity than primary memory. It is slower and cheaper than the main memory. But, it cannot be accessed directly by the CPU.

Data Transfer between Memory and CPU

Both the CPU and primary memory, as well as primary and secondary memory, require data transfers. Data are transferred between different components of a computer system using physical wires called bus.

Bus is of three types —

1. Data bus – to transfer data between different components,
2. Address bus – to transfer addresses between CPU and main memory.
3. Control bus – to communicate control signals between different components of a computer.

Microprocessor

A microprocessor is a small electronic component within a computer that performs a variety of arithmetic, logical, and data processing-related activities. A modern microprocessor is constructed on an integrated circuit that contains millions of small parts, including resistors, transistors, and diodes.

Microprocessor Specifications

Microprocessors are classified on the basis of different features which include chip type, word size, memory
size, clock speed, etc. These features are briefly explained below:

Word Size – Word size is the maximum number of bits that a microprocessor can process at a time. Earlier, a word was of 8 bits and now it is 64 bits.

Memory Size – Depending upon the word size, the size of RAM varies. Initially, RAM was very small (4MB) due to 4/8 bits word size. As word size increased to 64 bits.

Clock Speed – The quantity of pulses produced by the clock within a computer every second is known as the clock speed. The clock speed reveals how quickly a computer can carry out instructions. Measurement of clock speed in Hertz (Hz), Kilohertz (kHz), or Gigahertz (GHz).

Cores – The CPU’s core is its fundamental computational unit. Earlier processors could only handle one task at a time since they only had one computing unit. The introduction of multicore processors has made it feasible for the computer to carry out numerous tasks at once, improving system performance.

Microcontrollers

As opposed to a microprocessor, which has only a CPU on the chip, a microcontroller is a compact computing device that has a CPU, a defined amount of RAM, ROM, and other peripherals all incorporated on a single chip. As an example, a fully automatic washing machine uses its microcontroller to automatically manage the washing cycle.

Data and Information

Everything which is meaningful is known as data by a computer system, including instructions, photographs, songs, films, documents, etc. Raw, unorganised facts can also be considered to be data, which is processed to produce valuable information. There are three types of data –

1. Structured Data
2. Un-Structured Data
3. Simi Structured Data

Structed Data – Data that is simple and complies to a specific record structure structured data is data that is easy to understand. Such information along a data file may contain tabular information in a predetermined format.

Un-Structured Data – Unstructured data refers to data that are not organised into a predetermined record format. Examples include text papers, pictures, social media posts, satellite photographs, audio and video files, and more.

Simi Structured Data – Semi-structured data refers to data that lacks a clear structure but nevertheless maintains internal tags or markers to distinguish data items. Examples include email, HTML pages, CSV files, and documents with comma-separated values.

What is Software?

The software consists of a set of instructions that produce the desired result. In other words, every piece of software is created with computation in mind. Operating systems like Ubuntu or Windows 7/10, word processors like LibreOffice or Microsoft Word all are software.

Depending on the mode of interaction with hardware and functions to be performed, the software can be broadly classified into three categories viz.

1. System software,
2. Programming tools
3. Application software.

System Software – System software is the software that directly interacts with a computer’s hardware to offer the fundamental functionality needed to run the device. A system software programme can use and operate various computer hardware parts. for example operating systems, system utilities, device drivers, etc.

• Operating System – The operating system is a system software that operates the computer for example, Windows, Linux, Macintosh, Ubuntu, Fedora, Android, iOS, etc.
• System Utilities – Software used for maintenance and configuration of the computer system is called system utility. for example, anti-virus software, disk cleaner tool, disk compression software, etc.
• Device Drivers – The device driver acts as an interface between the device and the operating system for example, language translator, a device driver acts as a mediator between the operating system and the
  attached device. 

Programming Tools – In order to complete some work we have to provide the computer with  guidelines that are applied to the computer to achieve the desired result.  Languages for computers are created  for creating these guidelines. for example, Compilers, Interpreter, assemblers, and code editors.

• Classification of Programming Languages – Assembly language or High level language was created to make writing code easier by allowing the use of English-like phrases and symbols in place of 1s and 0s. 
• Language Translators – A translator is required to translate programmes written in assembly or high level language to machine language which helps to understand easily.
• Program Development Tools – A text editor is necessary every time we decide to build a programme. A text editor is a piece of software that enables us to write instructions in a text file and save it as the source code.

Application Software – Application software is a type of computer programme that carries out a specified task for the user. for example, Microsoft Suite. Office, Excel, Word, PowerPoint, chrome, safari etc. There are again two broad categories of application software — general purpose and customised application software.

• General Purpose Software – General purpose software refers to application software created for generalist applications in order to serve a larger audience generally. Such ready-made application software can be used by end users as per their requirements. For example, spreadsheet tool Calc of LibreOffice.
• Customised Software – These are specialised applications that have been created to satisfy the needs of a particular business or person. School management software, accounting software, etc. are a few examples of customised software.

Proprietary or Free and Open Source Software

Open source software is a free software and is made available to anyone who requests it, and programmers are free to view or modify it without permission of developer. For example, the source code of operating system Ubuntu is freely accessible for anyone with the required knowledge to improve or add new functionality. More examples of Open Source Software are Python, Libreoffice, Openoffice, Mozilla Firefox, etc.

Operating System

A platform between the user and the computer is the operating system. An operating system (OS) is a piece of software that controls all other application programmes in a computer after being originally loaded by a boot programme. Examples of popular OS are Windows, Linux, Android, Macintosh and so on. 

OS User Interface

There are different types of user interfaces each of which provides a different functionality. Some commonly used interfaces are –

• Command-based Interface – A user using a command-based interface must type the commands to carry out various activities, such as creating, opening, editing, or deleting a file. MS-DOS and Unix are two examples of operating systems with a command-based interface.
• Graphical User Interface – Through the use of icons, menus, and other visual options, the Graphical User Interface (GUI) enables users to run programmes or provide commands to the computer. Microsoft Windows, Ubuntu, Fedora, Macintosh, and other operating systems are examples of systems with graphical user interfaces.
• Touch-based Interface – The two most well-known operating systems featuring touch-based user interfaces are iOS and Android. Touch-based interfaces on touchscreen devices are likewise supported by Windows 8.1 and 10.
• Voice-based Interface – The user having a special needs and those who want to use computers or cellphones while completing other tasks, they can use voice – based interface software. like iOS (Siri), Android (OK Google or Google Now), Microsoft Windows 10 (Cortana), and so forth.
• Gesture-based Interface – Some Android- and iOS-based smartphones, as well as some laptops, give the facilities to interact with the devices via gestures including shaking, tilting, and eye movements.

Functions of Operating System

Essential functions and duties that an operating system does for the management of the computer system are –

Process Management – Process management includes numerous activities such as process creation, scheduling, process termination, and a deadlock. A process is an active programme, and they play an essential role in modern operating systems. The OS must allot resources to allow processes to communicate and share data.

Memory Management – Memory management involves controlling how much of the system’s primary memory is used by various programmes while monitoring whether or not each and every location in the memory is free or occupied.

File Management – In a computer system’s secondary storage, data and applications are kept as files. In the secondary memory, file management entails the creation, updating, deletion, and protection of these files.

Device Management – There are numerous hardware and I/O devices attached to a computer system. These interdependent heterogeneous devices are managed by the operating system. The device driver and associated software for a specific device are in communication with the operating system. Additionally, the operating system must offer options for setting a specific device so that it can be used by a user or another device.

Logical Gate

Logic gate is used to design electronic circuit, Logic gate operation are based on one or more input and produce a single output. The most common types of logic gates are AND gate, OR gate, NOT gate, NAND gate, NOR gate, XOR gate, and XNOR gate. These gates are help to build digital circuits and make decisions making on the input signals.

1. AND gate: It outputs “1” if and only if all of its inputs are “1”.
2. OR gate: It outputs “1” if any of its inputs are “1”.
3. NOT gate: It inverts the input signal. If the input is “1”, the output is “0”, and vice versa.
4. NAND gate: It is the negation of AND gate. It outputs “0” if and only if all of its inputs are “1”.
5. NOR gate: It is the negation of OR gate. It outputs “0” if any of its inputs are “1”.
6. XOR gate: It outputs “1” if exactly one of its inputs is “1”.
7. XNOR gate: It is the negation of XOR gate. It outputs “1” if all of its inputs are the same.

De Morgan’s laws

De Morgan’s laws are two fundamental boolean algebraic rules that describe how conjunction (AND) and negation (NOT) relate to disjunction (OR). These principles, which bear the name Augustus De Morgan after the British mathematician, offer a means to simplify boolean expressions.

According to the first law, the disjunction (OR) of two propositions’ negations is equal to the negation of a conjunction (AND) of two propositions. This can be written mathematically as:
NOT (A AND B) = (NOT A) OR (NOT B)

According to the second law, the conjunction (AND) of the negations of two propositions is equal to the negation of an OR between them. This can be written mathematically as:
NOT (A OR B) = (NOT A) AND (NOT B)

Logic Circuits

A logic circuit is a digital circuit that generates an output by carrying out one or more logical operations on binary inputs. Basic logic gates like AND gate, OR gate, NOT gate, NAND gate, NOR gate, XOR gate, and XNOR gate are used in various combinations to achieve more complicated functions in logic circuits.

Many different functions, including data processing, information storing and decision-making can be carried out by logic circuits. Logic circuits are employed in digital electronics to regulate data flow and carry out actions on binary signals.

A key component of computer engineering and electronics, logic circuit design and implementation is utilised in a wide range of contemporary technologies, including control systems, computer hardware and telecommunications .

Number System

Different bases or radix points are used in number systems to represent numbers. The four most widely used number systems are hexadecimal, octal, binary, and binary.

• Binary: Only the digits 0 and 1 are used in the base-2 number system known as binary to represent numbers. Electronics that use digital frequently use it.
• Octal: It is a base-8 number system that represents numbers with eight digits, ranging from 0 to 7.
• Decimal is a base-10 number system that represents numbers using ten digits, ranging from 0 to 9. It is the number system that is most frequently utilised in daily life.
• Hexadecimal is a base-16 number system that represents numbers with sixteen digits (0 to 9) and letters (A to F). It is frequently employed when programming computers.

Encoding schemes

In computers and other electronic devices, characters, symbols, and words are represented using encoding systems. The encoding systems available are ASCII, ISCII, and UNICODE.

• ASCII: The American Standard Code for Information Interchange is a 7-bit encoding technique. The 26 letters of the alphabet, 10 numerals, as well as additional punctuation and control characters, total 128 characters.
• ISCII: Indian Standard Code for Information Interchange, or ISCII, is an 8-bit encoding system. It symbolises the alphabetic symbols found in Indian languages, such as Bengali and Devanagari.
• UNICODE: Characters from practically all writing systems throughout the world are represented by the multi-byte encoding standard known as UNICODE. UTF-8 and UTF-32 are just two of the implementations that are included.
• UTF-8: A minimum of 8 bits are used in the variable-width encoding technique known as UTF-8. Both ASCII and the entire UNICODE character set are supported, and it is backwards compatible with ASCII.
• UTF-32: A fixed-width encoding method called UTF-32 employs 32 bits per character. Although it supports the entire UNICODE character set, UTF-8 is more effective in terms of storage and transmission.

Computer Science Class 11 Notes

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 MCQ

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples in Python
• Unit 2 : Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer Science Class 11 NCERT Solutions

• Unit 1 : Basic Computer Organisation
• Unit 1 : Encoding Schemes and Number System
• Unit 2 : Introduction to problem solving
• Unit 2 : Getting Started with Python
• Unit 2 : Conditional statement and Iterative statements in Python
• Unit 2 : Function in Python
• Unit 2 : String in Python
• Unit 2 : Lists in Python
• Unit 2 : Tuples and Dictionary in Python
• Unit 3 : Society, Law and Ethics

Computer