- DIN
- Objectives
- Activity 1 – Character Sets
- Activity 2 – Build Your Own
- Activity 3 –
Extending ASCII - Plenary
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Y10 AU – P7 – ASCII and Character Sets
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| ā±ļø Do It Now: |
| Provide screenshot evidence for each (1) Complete 2 hexadecimal conversions: Denary ā Binary ā Hex ā Nibbles Copy Checker (2) Complete 2X two’s complement conversions Two’s Complement Practice (3) Complete 2X logical shifts Binary Shift Practice (4) Complete 2X arithmetic shifts Arithmetic Shift Practice |
šÆ Learning Objectives
(1) We will learn what a character set is and why they are necessary
(2) We will learn about the ASCII character set and will be able to encode characters to binary data
(3) We will be able to describe the characteristics of standard ASCII and compare them to extended ASCII
š Activity 1 – Character Sets
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- Tab 2
- Tab 3
- Tab 4
What are character sets?
As computers store all data in 1s and 0s early computer scientists had to develop a way of representing text characters with 1s and 0s.
The first successful attempt at this (and something still used by computers) is ASCII
(American Standard Code For Information Interchange).
It uses a table to match each letter of the alphabet, number symbols and punctuation symbols to 7 digit binary numbers.
You can see the full table here
ASCII Facts
Ascii only uses 7 bits for each character
This gives us a maximum of 127 individual characters to work with
Number characters (0-9) are represented by 48 – 57
Uppercase letters at 65 – 90
Lowercase letters at 97 – 122
Everything in between is punctuation and special characters
Examples of ASCII Characters
Common examples:
A = 65 = 1000001
z = 122 = 1111010
It is easy to deduce that B would be 66 or 1000010
It is also easy to deduce that y would be 121 or 1111001
ASCII Binary Challenge
Use the clue to work out the ASCII value of the letter, then enter the correct 7-bit binary representation.
Screenshot your correct (glowing green) answers into OneNote
āØļø Activity 2 – Write your name in ASCII
Use this link to write your own name in ASCII: 8-Bit ASCII String Builder
Be aware, the app requires an 8 bit number (not a 7) so just put a 0 at the beginning
Screenshot the result into OneNote
š Expanding ASCII
- Tab 1
- Tab 2
- Tab 3
- Tab 4
- Tab 5
Not Just English Speakers
You might have noticed that ASCII is great for anyone who uses the English version of the alphabet.
What about other languages, for example German?
ASCII was extended to include these characters…
Extended ASCII also takes care of Norwegians
Extended ASCII VS Standard ASCII
Each character in Extended ASCII uses 8 bits e.g. 1111 0101
Standard ASCII characters are only 7 bits
With 8 bits, there are a potential 256 different characters available!
Standard ASCII can only offer 128 characters.
More Characters Needed
Extended ASCII enabled speakers of most European Languages to use computers, however there still weren’t enough!
What about Japanese?
They have three separate writing Systems!
Or Arabic, or even Cyrillic?
Extended ASCII couldn’t accommodate all of these…
Unicode
Unicode takes standard ASCII as its first 128 characters, however it can use up to 32 bits per character.
This means there are an incredible 4.3 billion characters!
This allows us to represent every writing system (including ancient writing systems like Ancient Egyptian)!
Unicode also allows us to use emojis!
Emoji Generator
Have a go at finding Emojis: Unicode Emoji Binary Builder
Screenshot what you have achieved into OneNote
š Plenary
Complete this quiz: ASCII and Unicode
Paste a screenshot of your result into OneNote
