# 1.1 Data Representation

 Data comes in many different forms, for example, it may be in the form of  Numbers – 10, 11.25, -30 etc., Text – “ Hello ! “ Audio – .mp3 Images – .bmp, gif, jpeg Videos – .avi All of the data is stored in computers as binary digits Data must be entered in a way that It captures the essence of the information. In the form, it is convenient for a computer to process.

How to represent data?

Humans have many symbolic forms to represent information such as Alphabets, numbers, pictograms. But, Computers can only represent information with electrical signals. A circuit can be OFF or ON.

Digital computers store information in Binary

Binary allows two states

• ON Yes     True    1
• OFF No       False  0
• Each digit in a binary number is called a bit

0          1          1          0 – bit

Off       On       On       Off Binary number system  = how numbers can be processed in Binary.

The BIT is a basic unit fo information in computing and digital communications. A bit can have only one of two values, therefore physically implemented with a two-state device. These values are commonly represented either as 0 or 1

The BYTE is a unit of digital information that most commonly consists of EIGHT BITS.

1 Bit = 0 or 1            (represented as b)

1 Byte = 8 bits         (represented as B) A NIBBLE is group of 4 bits. • Bit – a single binary digit
• Nibble – a group of four bits
• Byte – a group of eight bits
• Word – depends on the processor; 8,16,32,64 or more bits
• LSB – Least Significant Bit ( on the right )
• MSB – Most Significant Bit ( on the left )
 Data Measurement Chart 1 is 1 bit 0 is 1 bit 4 bits = 1 nibble 8 bits = 1 byte 1024 bytes = 1 kilobyte 1024 bytes = 1 1 megabyte 1024 megabytes = 1 gigabyte 1024 gigabyte = 1 terabyte 1024 terabytes= 1 petabyte 1024 petabytes = 1 exabyte 1024 exabytes = 1 zettabyte 1024 zettabytes = 1 yottabyte

## Number System

It is the set of rules and symbols to represent numbers. Binary Number System

The word binary is derived from the Latin word bini (two by two)

This system uses only two symbols (0 1), usually referred as binary digit or binary digits.

Decimal Number System

The Decimal number system is the commonly used term.

It is composed of ( 0 1 2 3 4 5 6 7 8 9 ). Using these numbers we express a quantity. The number base is also called as RADIX

Octal Number System

This system contains 8 digits (symbols) which are the first 8 decimal digits (0 1 2 3 4 5 6 7 )

There are no 8 & 9 in the Octal Number system.

Hexa Decimal Number System

It is derived from Greek hex(Six) and Latin decem(ten)

This system uses sixteen symbols to represent a number.

The set of symbols are (0 1 2 3 4 5 6 7 8 9 A B C D E F ) and the symbols A B C D E F are equivalent to 10 11 12 13 14 15.