What's covered
Key facts
Standard ASCII uses 7 bits per character, with 128 possible code values (0–127).
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.
In ASCII, capital 'A' is encoded as 65.
Unicode uses more bits per character on average because there are far more characters to distinguish.
Lowercase 'a' is ASCII 97.
Unicode covers most of the world's languages and scripts.
Standard ASCII canNOT encode Chinese, Arabic, or Japanese — it only covers the basic Latin alphabet.
Unicode includes emoji as well as letters.
ASCII is a character encoding standard that maps characters to numbers.
Modern Unicode can represent over a million possible characters (codepoints).
Sample questions
A taste of the 20 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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