1. Lecture 36 – Unit 6 – Under the Hood Binary Encoding – Part 2
CMPT 120
Lecture 36 – Unit 6 – Under the Hood
Binary Encoding – Part 2

2. Review – “Computers use 0 and 1 to represent everything“
Computer memory:
integer
floating point
number
colour
character
CPU instruction
sound

3. Review - Decimal numeral system
Binary numeral system
Decimal -> (Base 10)
Ten symbols (digits):
0, 1, 2, 3, 4, 5, 6, 7, 8, 9
Binary -> (Base 2)
Two symbols (bits): 0, 1 (bits -> binary digits)

4. Review - Decimal numeral system
Binary numeral system
Positional system
When counting:
Positional system
When counting:
0 0 1 …
0 0 9
0 1 0
0 1 1
1 9 9
2 0 0
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1 …
102
101 22 21 20
100

5. How computers represent integers
Which integer is this:
bit
byte
A bit either contains a 0 or 1
A byte is 8 bits

6. How computers represent integers
Which integer is this :

7. You try it!
Which integer is this?

8. Decimal numeral system
So far …
Decimal numeral system
Binary numeral system

9. Decimal numeral system
Let’s try …
Decimal numeral system
Binary numeral system

10. What is 106 as a binary number?

11. Can you convert these?
9 _ _ _ _ _ _ _ _
10 _ _ _ _ _ _ _ _
11 _ _ _ _ _ _ _ _
12 _ _ _ _ _ _ _ _
13 _ _ _ _ _ _ _ _
14 _ _ _ _ _ _ _ _
15 _ _ _ _ _ _ _ _
64 _ _ _ _ _ _ _ _
255 _ _ _ _ _ _ _ _
256 _ _ _ _ _ _ _ _

12. How can we read/write long binary numbers easily?

13. Hexadecimal Numbers

14. ASCII and Unicode

15. How computers represent characters
We have already seen how computers deal
with letters and characters … remember ASCII?
Source:
See ASCII Table:

16. Unicode UTF - 8
ASCII uses 8 bits (1 byte) to encode characters using 0’s and 1’s
How many different characters can we represent in ASCII with 8 bits (1 byte)?
To type in other languages than English, we may need a lot more than that
Unicode uses up to 4 bytes to handle more characters
Let’s have a look:

17. Other Character Encodings

18. I have a great idea! Let’s write a binary-decimal converter in Python
How would we go about solving this problem?

19. Next Lecture Practice speaking binary and hexadecimal and a lot more!
Bring your laptop! 