© OCR 2016 Unit 2.6 Data Representation Lesson 1 ‒ Numbers

© OCR 2016 Starter Put these units in the correct order of size (smallest->largest): Bit Gigabyte Kilobyte Byte Petabyte Terabyte Megabyte Nibble

© OCR 2016 Learning Objectives Define the units bit, nibble, byte, kilobyte, megabyte, gigabyte, terabyte, petabyte. Know how data needs to be converted into a binary format to be processed by a computer. Know how to convert positive denary whole numbers (0-255) into 8 bit binary numbers and vice versa Know how to convert from binary and denary into positive hexadecimal numbers (0-255) and back again

© OCR 2016 Units The following units describe how much disk space, capacity or data storage is used. Bit Nibble Byte Kilobyte Megabyte Gigabyte Terabyte Petabyte

© OCR 2016 Introduction to binary Unit 8 Data Representation What is this symbol? Why?

© OCR 2016 Introduction to binary Unit 8 Data Representation Creating a circuit Computers comprise billions of switches to turn voltage on and off

© OCR 2016 Introduction to binary Unit 8 Data Representation Representing values Consider the same byte value This is represented in denary as 57 As an electrical circuit this could be represented as:

© OCR 2016 Bit A 'bit' is a Binary Digit A Binary Digit is the smallest unit of data a computer can store Each 'bit' is represented using either a 1 (true) or 0 (false)

© OCR 2016 Nibble This is a less known term It describes a group of 4 bits A nibble is really useful when converting between binary and hexadecimal A Nibble will only cover decimal numbers between 0 and 15

© OCR 2016 Byte A 'byte' is a collection of 8 bits. It is the ‘building block’ for every other measurement Keyboard characters generally take up 1 byte (8 bits) of storage Every other storage measurement is made up from multiples of bytes

© OCR 2016 Kilobyte This is another common unit of measurements It can be written as kB or kbyte. A kilobyte can be thought of as 1,000 bytes However because we are counting in binary, it is actually 1024 bytes You may use either in an exam! Kilobytes are often used when talking about document file sizes

© OCR 2016 Megabyte A megabyte is the other most common unit of storage. It can be written as MB or mbyte. Like a byte, a megabyte can be thought of as either 1,000 or 1,024 kilobytes We also use megabytes to measure transmission speeds on the web and also storage space on a CD.

© OCR 2016 Gigabyte A Gigabyte is 1024 Megabytes Again you can also use 1,000 Megabytes for rough calculations It can be written as GB or gbyte You must be careful NOT to use Gb - this used for gigabit To give you an idea of storage sizes, 1 Gigabyte could hold: ‒ Over 3,000 books ‒ 25% of a typical movie We often use GB to refer to hard drive sizes

© OCR 2016 Terabyte Terabyte is written as TB This is 1,024 Gigabytes More and more hard disks are now measured in Terabytes A Terabyte can store: ‒ Over 300 hours of video ‒ 1,000 copies of the Encyclopaedia Britannica

© OCR 2016 Petabyte You write a petabyte as PB A Petabyte is 1024 Terabytes (again you can use 1,000 in exams) A Petabyte is a massive amount of storage. It could hold: ‒ Over 2,000 years worth of songs, back to back ‒ 315 million photos (3MB each)

© OCR 2016 Activity 1 Create a Poster that defines all of the different units of storage. Your poster must include: An order to the units in how they are displayed Definition of each unit Examples of what could fit into that unit Colour that makes the poster engaging Stretch & Challenge Research and Include a section on what comes after Petabyte and what could possibly be stored with that capacity.