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Worksheet

F8.6 Characters: ASCII and Unicode

Data representation · GCSE · OCR J277 1.2.4, AQA 8525 3.3.5, Edexcel 1CP2 2.2.1 · about 12 min

BugBotLab
NameClassDate

What this lesson is about

Character sets, bits per character, and why Unicode was needed.

Questions 5 marks in all

  1. [1 mark]How many characters can 7-bit ASCII represent?

  2. [1 mark]Why was Unicode needed?

    1. AASCII has no room for the world's other writing systems and symbols
    2. BASCII was too slow
    3. CUnicode uses fewer bits
    4. DASCII cannot store digits

  3. [1 mark]ord('A') is 65. What is ord('D')?

  4. [1 mark]A 12-character message is stored in 7-bit ASCII. How many bits is it?

  5. [1 mark]What does this program print?

    print(len("robot".encode("utf-8")), len("机器人".encode("utf-8")))

The task: message sizes

For the message BugBot says hi, print three lines: characters: <n>, ascii bits: <n> for 7-bit ASCII, and utf-8 bytes: <n>. Then print the 7-bit binary code of each of its first three characters, one per line, such as B 1000010. Work everything out from the message.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

message = "BugBot says hi"

Plan your program here, then type it in and press Run.

QR code
Do it on the robot
www.bugbotlab.com/learn/f8-6-characters-ascii-and-unicode/
The simulator checks it and tells you when it passes. Nothing to install, no account.

Challenges

  1. Find the smallest code for a lower-case letter, and explain how to turn any capital into lower case with arithmetic.
  2. Send the robot's name as a string of 7-bit binary codes, and decode it again.
  3. Which uses fewer bytes in UTF-8: a tweet in English or the same length of emoji? Measure it.