Stretch tasks Storing Characters: ASCII and Unicode

Round 1: Quiz Blitz

1. A list of characters, each with a unique binary code Every character gets a number, and the number is stored in binary.
2. 7 7 bits give 2 to the power 7 = 128 characters. Extended ASCII uses 8.
3. 69 A 65, B 66, C 67, D 68, E 69. Count carefully: off by one is the classic slip.
4. False The character '5' has ASCII code 53. That is why "5" + "3" gives "53".
5. 128 7 bits give 128 codes. 256 is extended ASCII.
6. It can represent almost every written language; It includes emoji and mathematical symbols Unicode covers over a million characters, but it uses more bits, so files are bigger.
7. True So old ASCII text is still valid Unicode.
8. Each character uses more bits 16 or more bits per character instead of 7 or 8.
9. 100 a 97, b 98, c 99, d 100.
10. 256 2 to the power 8 is 256.
11. ASCII → Extended ASCII → Unicode 7 bits, then 8 bits, then 16 or more.
12. So codes turn back into the same characters With different sets, every message would arrive as gibberish.

Round 2: Quick Fire

1. • Computers only store binary, so each character is given a unique code
   • Devices must agree on the same set so text is shown correctly
   Model answer

   Computers can only store binary, so each character is given a unique binary code. Devices must agree on the same character set, or text sent from one would be shown as gibberish on another.

2. • K is 75
   • Letters are in order, and K is 10 letters after A
   Model answer

   K is 75. Letters are stored in order, and K is 10 letters after A, so its code is 65 + 10 = 75.

3. • Advantage: far more characters, so almost every language and emoji
   • Disadvantage: more bits per character, so larger files
   Model answer

   Advantage: Unicode can represent over a million characters, so it covers almost every written language. Disadvantage: it uses more bits per character, so text files are larger.

4. • The quoted values are characters or strings, not numbers
   • So + joins them together: concatenation
   Model answer

   "5" and "3" are strings of characters, not numbers, so + joins them together, which is concatenation, giving "53". Without the quotes they are numbers, so + adds them to give 8.

Round 3: Big Think

1. • ASCII uses 7 bits, so it only has 128 characters
   • ASCII only covers English and basic symbols
   • Unicode covers almost every written language, such as Chinese and Arabic
   • Unicode also has emoji
   • So names with accents are stored and displayed correctly
   Model answer

   ASCII uses 7 bits, so it only has 128 characters, which covers English and basic symbols only. Customers from around the world will write in many languages, such as Chinese, Arabic and Greek, and use accents in their names. Unicode can represent over a million characters, covering almost every written language and emoji too, so every review would be stored and displayed correctly.

2. • ASCII uses 7 bits per character
   • ASCII has 128 characters
   • Extended ASCII uses 8 bits for 256 characters
   • Unicode uses 16 bits or more per character
   • Unicode has over a million characters, covering almost every language
   • Unicode files are larger for the same text
   • The first 128 Unicode codes are the same as ASCII
   Model answer

   ASCII uses 7 bits per character, so it can represent 128 characters: English letters, digits, punctuation and control characters. Extended ASCII uses 8 bits for 256 characters. Unicode uses 16 bits or more per character, so it can represent over a million characters, covering almost every written language as well as emoji. The first 128 Unicode codes are the same as ASCII, so ASCII text is still valid. The drawback of Unicode is that it uses more bits per character, so the same text gives larger files that need more storage and bandwidth.

This or That

1. Unicode ASCII's 128 characters cover English only. Unicode covers almost every writing system.
2. 89 Y comes just before Z, so it is one less.
3. ASCII ASCII needs 7 bits a character. Unicode needs 16 or more.
4. 32 A space is a character too, with code 32.
5. Lower: it is 65 Upper case letters come first in ASCII: A is 65 and a is 97.
6. No: its ASCII code is 55 The digit characters start at 48 for '0', so '7' is 55.
7. No: ASCII is its first 128 codes Unicode kept ASCII's codes, so ASCII text is still valid.
8. The character set Both devices must turn the same codes into the same characters.

Memory Match

• A 4 ASCII: 7 bits, 128 characters
• B 1 Extended ASCII: 8 bits, 256 characters
• C 5 Unicode: 16 or more bits, over a million characters
• D 2 Character set: Characters with their unique binary codes
• E 6 Character code: The number given to one character
• F 3 A: Code 65 in ASCII

Sort It

1. ASCII only Covers English letters and basic symbols only That is ASCII's big limit, and the reason Unicode was created.
2. Both Stores A as code 65 Unicode's first 128 codes are the same as ASCII.
3. Unicode only Makes files larger for the same English text More bits for every character means a bigger file.
4. Unicode only Can store emoji Emoji are in Unicode, not ASCII.
5. ASCII only Uses 7 bits per character Standard ASCII uses 7 bits. Unicode uses 16 or more.
6. Unicode only Can store Chinese, Arabic and Greek Unicode covers almost every writing system.
7. Both Stores characters in order, so B is one more than A Both keep letters in a logical order, which is why you can count on from A.
8. Both Gives each character a unique binary code Every character set does that.
9. Unicode only Uses 16 or more bits per character More bits per character is how Unicode fits so many in.
10. ASCII only Has exactly 128 characters 2 to the power 7 is 128. Unicode has over a million.