How to be a Programmer | Part 6 : Coding Systems in Computer

Coding Systems in Computer

Coding Systems in Computer

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What is Coding Systems in Computer?

According to the above part 5 article (How to be a Programmer | Part 5 : Number Systems), when you enter a data to the computer, it converts the data to binary patterns. Thus, binary codes are used when storing, numbers, letters, special characters, videos, sounds and images in storage devices of computers. Following are different coding systems used,

  • BCD – Binary Coded Decimal
  • ASCII – American Standards Code for Information Interchange
  • EBCDIC – Extended Binary Coded Decimal Interchange Code
  • Unicode

BCD – Binary Coded Decimal

This coding method was used in the early stage of computing. BCD takes advantage of the fact, That any decimal numeral can be represented by a four-bit pattern. BCD is used only to represent decimal numbers. 16 (24) symbols can be represented in this system. The main advantage of BCD is that it easy to encode and decode between decimal and binary form.

Decimal Numbers and BCD Values for the 10 Digits

Example: Indicating number 15710 in BCD codes.

1 -> 0001 (BCD)
5 -> 0101 (BCD)
7 -> 0111 (BCD)

1 5 710 = 0001 0101 0111

15710 = 000101010111 (BCD)

ASCII – American Standard Code for Information Interchange

ASCII coding system used 7-bit binary digit. 128 (27) symbols can represent in these systems. It is used to represent text and numbers (numbers from 0-9, the UPPER and lower case English letter from A-Z). It is designed and approved by ANSI (American National Standard Institute) in the early ’60s. ASCII was the first standard character set used between computers and the internet.

7-bit ASCII Character Codes

Example: Indicating the word CtechF in ASCII codes.

C – 067 / t – 116 / e – 101 / c – 099 / h – 104 / F – 070

ASCII Value = 067 116 101 099 104 070

Hex Value = 43 74 65 63 68 46

Binary Value = 01000011 01110100 01100101 01100011 01101000 01000110

EBCDIC – Extended Binary Coded Decimal Interchange Code

EBCDIC coding systems use 8-bit binary digits. this code system allows the use of 256 (28) characters. This system was used in IBM mainframe computers.

Example: Indicating the word CtechF in EBCDIC codes.

C – 195 / t – 163 / e – 133 / c – 131 / h – 136 / F – 198

EBCDIC Value = 195 163 101 131 136 198

Hex Value = C3 A3 85 83 88 C6

Binary Value = 11000011 10100011 10000101 10000011 10001000 11000110


Unicode coding systems is a computing industry standard of the consistent encoding. Unicode 1.0 was the 1st version of Unicode. It released in October 1991. It allows the use of 7,161 new characters. Latest Unicode 12.1 was released in May 2019. It allows the use of 137,929 characters. It covering 150 modern and historic scripts. Unicode system provides a unique number for every character. It can be used to represent different languages, symbols, special characters, and emojis.

List of Unicode Characters

Example: – Photos, Videos and Graphic Data

All of the images are made out of tiny dots called pixels. (pictures element) Pixel is the smallest unit of a digital image or graphic. In color pictures, each pixel is represented by three binary sequences. (24-bit) That corresponds to the primary colors (Red, Green, Blue). each sequence (8-bit) encode a number that determines the intensity of that particular color. When you consider that a typical image has millions of pixels. for example, an image with a resolution of 1024 x 760 will produce a maximum of 778,240 pixels. And the regular video displays 30 images per second. It contains +2.5 billions of pixels per minute.


Coding Systems in Computer

RGB (0, 188, 212)
Red – 000000 / Green – 10111100 / Blue – 11010100
Hex Code – 00 bc d4 (#00bcd4)

Example: – Sounds

Every sound is basically a set of vibrations. Vibration can be represented graphically as a waveform. Any duration on this waveform can be represented by a number. And this way, any sound can be presented into a set of binary codes.

Sources: (Images)
ICT Books (Details)

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