What's A Gigabyte Anyway?
Time 1.3 hrs

Difficulty Intermediate
Prerequisites Multimedia Basics
Departments Human Technologies
Authors Ross Parker
Groupings Individual
Pairs
Minimum Year Group None

### Blurb

In this unit you will explore binary, bits and bytes.

This work is shared under the following license: Creative Commons BY-SA-NC

### Outline

 CreditsAny CC attribution, thanks, credit, etc. Big Data thumbnail by freepik on freepik under Freepik License. 10 Types of People image copyright Redbubble, used under fair use. ASCII To Decimal Chart screenshot copyright Appropriate Solutions, Inc., used under fair use. What Is A Petabyte infographic copyright Gizmodo, used under fair use.

5 mins
Binary
All 0s and 1s
• Computers are complex machines that work by storing the simplest of values:
• 0 (also known as false or off)
• 1 (also known as true or on)
• This is called binary or base-2.
• This unit won't teach you lots about binary, but there are other units that will.
• For now you just need to know that computers use binary to store data.
• In ICT we call a single 0 or 1 a bit (short form binary digit)
• If you understand binary, you will get the following joke:

• Don't worry if you don't get it...you might one day!

5 mins
Bytes
8 Bit
• In computers, groups of 8 bits are stored together in a Byte.
• b stands for bit, B stands for Byte.
• A byte will look something like this:
• 10010111
• A byte can be used to:
• Store a number of 0 to 255.
• Store a letter of the alphabet, and some other special symbols like !, ? or @.
20 mins
ASCII
Letters
• ASCII (pronounced as-key) is a system that computers use to store characters (letters, numbers, special symbols).
• Instead of storing a letter directly, ASCII stores characters as numbers.
• For example A is the number 65 and a is the number 97
• You can use the chart below to see how different characters are represented as numbers in ASCII (click for a larger version):

• I could use ASCII to write my name (Ross Parker) as follows:

82 111 115 115 32 80 97 114 107 101 114

• Take some time now to write your name in ASCII.
• However, as computers can only store binary, a computer would store my name as:

01010010 01101111 01110011 01110011 00100000 01010000 01100001 01110010 01101011 01100101 01110010

15 mins
Gigabytes
Many, Many Bytes
• Because computers store so much information, we often don't count in bytes, but use groups of bytes.
• You may have heard of a gigabyte, or other groups such as kilobytes and megabytes.
• The table below shows what these things are:

1 bit (b) = a single 0 or 1

1 byte (B) = 8 bits

1 kilobyte (KB) = 1024 bytes

1 megabyte (MB) = 1024 kilobytes

1 gigabyte (GB) = 1024 megabytes

• This means that a gigabyte is a collection of 8,589,934,592 bits.
• Or 1 x 8 x 1024 x 1024 x1024
• That's a lot of data!
10 mins
Petabytes
Even more Numbers
• If you want some even bigger numbers:

1 terabyte (TB) = 1024 gigabyte

1 petabyte (PB) = 1024 terabytes

1 exabyte (EB) = 1024 petabytes

1 zettabyte (ZB) = 1024 exabytes

1 yottabyte (YB) = 1024 zettabytes

• It is very hard to imagine how big these numbers are, but the image below might help you get a handle on the size of a petabyte:

20 mins
Finishing Up
Evidence
• To show what you have learned in this unit:
• Give the document a title
• Write your name in ASCII using regular numbers
• Write your name in ASCII using binary numbers
• Make a guess at how many bytes of information are contained in the whole English language version of Wikipedia.