ASCII & Unicode
Unit 5 Summary - part 1
ASCII has 128 characters and 7 bits of binary.
An example of finding ASCII codes.
Unicode is invented because ASCII doesn't support these:
1. Other languages' writings.
2. Vowels & consonants accents.
3. icons, emoticons, emojis
Every letter we type can be ASCII or Unicode.
ASCII is included in Unicode, that's why Python uses Unicode.
To find a character's Unicode, use ord on Python:
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Character = input("Enter a single character: ")
if len(Character)>1:
Character = Character[0]
print("the character", Character, "has the ASCII or Unicode value", ord(Character))
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To find a Unicode's character, use chr on Python:
Code = input("Enter a Unicode value: ")
Code = int(Code)
print("The Unicode value", Code, "represents the character",chr(Code))
Oxford AQA IGCSE 2019
10.1.
The ASCII code of the character 'A' is 65 in decimal.
A memory location contains the binary pattern 1000101 This binary pattern is for an ASCII code.
What character does this binary pattern represent? [1 mark]
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Answer:
Put the binary in this table:
Start calculating every top row that has 1 in it: 64+4+1 = 69
If A is 65, that means 69 is E.
10.2.
State two advantages of Unicode compared to ASCII. [2 marks]
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Alternative answers:
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Can represent more characters / can represent special characters
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Can represent alphabets with lots of characters / can represent multiple/different alphabets;
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Unlike ASCII, Unicode is consistent across countries;
Oxford AQA IGCSE 2020
11.1.
The ASCII character code for a is 1100001
Complete the table below to show how the string cab would be encoded as a bit pattern using ASCII. [2 marks]
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Answers:
You don't need to calculate
"a" = 1100001
Always add from the right. To add 1, change the right 0 into 1, and change the end right to 0.
"b" = 1100010
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The same goes to c. To add 1, change the right 0 into 1.
"c" = 1100011
11.2.
How many different characters can be encoded using ASCII? [1 mark]
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Answers:
Normal ASCII only has 7 bits. The answer is 128. Remember this.
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Because if you start creating this column:
Put all 1 in all columns, you'll get this calculation:
64+32+16+8+4+2+1 = 127 and one more character of index number 0, so it's 128.
Oxford AQA IGCSE Specimen Paper
1.6.
ASCII uses 7 bits to represent a character. How many different characters can be represented using ASCII? [1 mark]
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Final Answer:
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1.7.
How many extra bits would be needed to represent twice as many characters as ASCII can represent? [1 mark]
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Final Answer:
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Oxford AQA IGCSE Mock Paper
1.3.
The ASCII code of the letter ‘A’ is 65 in decimal.
What is the ASCII code of the letter ‘D’ in binary? [1 mark]
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