What's covered
Key facts
ASCII — Characters as Numbers
Standard ASCII uses 7 bits per character, with 128 possible code values (0–127).
Unicode — Beyond ASCII
The first 128 Unicode characters are identical to ASCII (one-to-one), so plain ASCII text is also valid Unicode — they are NOT completely different systems.
ASCII — Characters as Numbers
In ASCII, capital 'A' is encoded as 65.
Unicode — Beyond ASCII
Unicode uses more bits per character on average because there are far more characters to distinguish.
ASCII — Characters as Numbers
Lowercase 'a' is ASCII 97.
Unicode — Beyond ASCII
Unicode includes emoji as well as letters.
ASCII — Characters as Numbers
Standard ASCII canNOT encode Chinese, Arabic, or Japanese — it only covers the basic Latin alphabet.
Unicode — Beyond ASCII
Modern Unicode can represent over a million possible characters (codepoints).
ASCII — Characters as Numbers
ASCII is a character encoding standard that maps characters to numbers.
Unicode — Beyond ASCII
Unicode is NOT limited to English — it covers Chinese, Arabic, Japanese, Hindi, Hebrew, Cyrillic, and many more.
Sample questions
A taste of the 17 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
Why do computers need character codes?
- •To make characters appear bigger
- •To make the keyboard run faster
- •To remove characters from screen
- ✓To store text as numbers internally
Why was Unicode created?
- •To reduce the file size of text documents
- •To replace binary with a faster encoding
- •To standardise keyboard layouts worldwide
- ✓To support more languages
What is the ASCII code for lowercase 'a'?
- •Forty-eight (48, the digit 0 code)
- ✓Ninety-seven (97, lowercase)
- •Sixty-five (65, capital A code)
- •Thirty-two (32, the space code)
How does Unicode compare to ASCII?
- •Is exactly the same as ASCII
- •Supports far fewer characters
- ✓Supports far more characters
- •Uses no bits per character
How many bits does standard ASCII use per character?
- •Eight bits per char
- ✓Seven bits per char
- •Sixteen bits per char
- •Thirty-two bits per char
Roughly how many characters can modern Unicode represent?
- •Just one thousand characters
- •Just ten thousand characters
- •Just two hundred characters
- ✓Over one million characters
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