Page 55 - ComputerScience_Class_11

eNcodiNgS

2

Learning Objectives

2.1 Characters and their Encodings

Data is a collection of raw facts and figures which when processed gives meaningful information. Data that we use in
our daily life can broadly be classified as numeric and text. But internally, digital computers represent data in binary
form. A binary digit or bit comprises only two values 0 and 1.

A byte is a unit that most computers use to represent any character. 8 bits make a byte. A word is a unit of data of a
defined bit length that can be addressed and moved between storage and the computer processor. The word length
varies depending on the computer architecture. In IBM architecture, a word is 32 bits or four bytes whereas in Intel’s
PC processor architecture, a word is 16 bits or 2 bytes.

The tabular representation of various memory sizes is given below:

Name Size

bit (b) 1 bit
nibble 4 bits
byte (B) 8 bits

kilobyte (KB) 1024 bytes
megabyte (MB) 1024 kilobytes
gigabyte (GB) 1024 megabytes

terabyte (TB) 1024 gigabytes
petabyte (PB) 1024 terabytes

exabyte (EB) 1024 petabytes
zettabyte (ZB) 1024 exabytes
yottabyte (YB) 1024 zettabytes

When you input text, the character encoding maps characters you choose to specific bytes in computer memory.
To output the same, it reads the bytes back into characters. A character encoding provides a key to unlock this binary
code. It is a set of mappings between the bytes in the computer and the characters in the character set.

Encodings 53