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2.6 - DATA REPRESENTATION (REPRESENTATION CHARACTERS (E (Text and…
2.6 - DATA REPRESENTATION
BINARY
Computers use binary - the digits 0 and 1 - to store data. A binary digit, or bit, is the smallest unit of data in computing. It is represented by a 0 or a 1. Binary numbers are made up of binary digits (bits), eg the binary number 1001.
UNITS
Bits, Bytes, Kilobytes, Megabytes, Gigabytes, Terabytes and Petabytes are all different forms of describing data storage or the capacity of the system memory.
Bit
Two possible values - 0 and 1
Nibble - 4 bits
a group of 4 bits, e.g. 1001
Byte - 8 bits
8 bits - a single character takes up one byte of storage, e.g. A = 01000001
Kilobyte - 1024 bytes
2 to the power of 10 bytes.
Megabyte - 1024 KB
An MP3 song can be between 3 and 5 megabytes.
Gigabyte - 1024 MB
A DVD can be 4-8 GB in size.
Terabyte - 1024 GB
Most hard disks nowadays are 1 - 10 TB.
Petabyte - 1024 TB
Data centres and supercomputers use PB.
REPRESENTATION CHARACTERS
E
Text and characters need to be represented in binary form
Text and characters need to be converted to binary form
Text and characters - letters (upper and lowercase), numbers and symbols. Look at your keyboard
Binary form - 0 and 1
Standard ASCII
Uses binary code to represent each character, number and symbol in the chosen language. It stands for The american Standard Code for Information Interchange
It is a 7-bit system., so gives 128 possible values 2x2x2x2x2x2x2=128
EXTENDED ASCII
Other languages, such as German, French, Spanish, Finnish, Russian, etc. need to use more characters than we do, so use extended ASCII, which uses 8-bits, so has 258 possible values.
But, there is not a single agreed-upon standard for Extended ASCII. So, the same values in one set may represent an entirely different character to another.