Class 11 Encoding Schemes Notes: Important Points
Class 11 Encoding Schemes Notes: Important Points
Introduction
We know computer understands only binary language of 0s and 1s. Therefore, when a key on the keyboard is pressed, it is internally mapped to a unique code, which is further converted to binary.
For example:
When the key ‘A’ is pressed, it is internally mapped to a decimal value 65, which is then converted to its equivalent binary value for the computer to understand.
| Alphabet | Decimal Value | Binary Value |
| A | 65 | 01000001 |
| a | 97 | 01100001 |
What is encoding?
The mechanism of converting data into an equivalent cipher using specific code is called encoding.
It is important to understand why code value 65 is used for the key “A” and not any other value? Is it same for all the keyboards irrespective of their make?
Yes, it is same for all the keyboards. This has been possible because of standard encoding schemes where each letter, numeral and symbol is encoded or assigned a unique code. Some of the well-known encoding
schemes are:
American Standard Code for Information Interchange (ASCII)
In the early 1960s, computers had no way of communicating with each other due to different ways of representing keys of the keyboard. Hence, the need for a common standard was realised to overcome this shortcoming. Thus, encoding scheme ASCII was developed.
Initially ASCII used 7 bits to represent characters. Therefore, total number of different characters on the
English keyboard that can be encoded by 7-bit ASCII code is 27 = 128. Following table shows some printable
characters for ASCII code.
| Character | Decimal Value | Character | Decimal Value | Character | Decimal Value |
| Space | 32 | A | 65 | a | 97 |
| ! | 33 | B | 66 | b | 98 |
| “ | 34 | C | 67 | c | 99 |
| # | 35 | D | 68 | d | 100 |
| $ | 36 | E | 69 | e | 101 |
| % | 37 | F | 70 | f | 102 |
| & | 38 | G | 71 | g | 103 |
NOTE: ASCII is able to encode character set of English language only
Example 1: Encode the word DATA and convert the encoded value into binary values which can be understood by a computer.
ASCII value of ‘D’ is 68 and its equivalent 7-bit binary code = 1000100
ASCII value of ‘A’ is 65 and its equivalent 7-bit binary code = 1000001
ASCII value of ‘T’ is 84 and its equivalent 7-bit binary code = 1010100
ASCII value of ‘A’ is 65 and its equivalent 7-bit binary code = 1000001
Replace each alphabet in DATA with its ASCII code value to get its equivalent ASCII code and with 7-bit binary code to get its equivalent binary number.
Indian Script Code for Information Interchange (ISCII)
In order to facilitate the use of Indian languages on computers, a common standard for coding Indian scripts called ISCII was developed in India during mid 1980s. It is an 8-bit code representation for Indian languages
which means it can represent 28=256 characters.
UNICODE
There were many encoding schemes, but they were not able to communicate with each other. Hence, text
created using one encoding scheme was not recognised by another machine using different encoding scheme.
Therefore, a standard called UNICODE has been developed to incorporate all the characters of every written language of the world. UNICODE provides a unique number for every character, irrespective of device (server, desktop, mobile), operating system (Linux, Windows, iOS). Commonly used UNICODE encoding are UTF-8, UTF-16 and UTF-32. It is a super set of ASCII.
Unicode characters for Devanagari script is shown below. Each cell of the table contains a character along with its equivalent hexadecimal value.
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Disclaimer : I tried to give you the simple notes of ” Class 11 Encoding Schemes Notes: Important Points” , but if you feel that there is/are mistakes in the handouts or explanation of “Class 11 Encoding Schemes Notes: Important Points“ given above, you can directly contact me at csiplearninghub@gmail.com. The above Notes of “Class 11 Encoding Schemes Notes: Important Points ” are created by referring NCERT Book of Class 11. Screenshots used in this article are taken from NCERT book.