1. Essence of Computation
CSCI N100
Essence of Computation
Learning how computers think

2. Definition of computer
Universal
Information
Manipulator

3. Universal Works with all kinds of information
Does all kinds of stuff to it
Very few limitations

4. Information Seems to be able to work with anything
Actually very limited
Tiny pieces of data combined into complex information

5. Manipulator Seem able to do anything with data Actually very limited
Simple commands combined into complex instructions

6. Computers and Information
Information limited to on/off impulses
Like a light switch
Infinite positions
Two outcomes

7. Working with Multiple Switches
One switch - two messages
Two switches - four messages
Three switches - eight messages

8. Assigning Values to messages
Looking at the pattern
1, 2, 4, 8, 16, 32, 64,
Seeing how it works…

9. Conversion Chart Binary to Decimal28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1

10. Conversion Chart Binary to Decimal28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1  0

11. Conversion Chart Binary to Decimal28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1  0
 8x1
 4x1
 0x2
 1x0

12. Conversion Chart Binary to Decimal28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1  0
 8x1
 4x1
 0x2
 1x0
 8+
 4+
 0+
1101 = 13

13. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1 22

14. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1 22
The 1st number that is equal to or less than the decimal number

15. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1 22
Subtract 22 – 16 remainder of 6

16. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1 22
Subtract 22 – 16 remainder of 6

17. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1  0
Subtract 22 – 16 remainder 6
Subtract 6 – 8?

18. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1  0
Subtract 22 – 16 remainder 6
Subtract 6 – 8?
Subtract 6 – 4 remainder 2

19. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1  0
Subtract 22 – 16 remainder 6
Subtract 6 – 8?
Subtract 6 – 4 remainder 2
Subtract 2 – 2 remainder 0

20. Conversion Chart Decimal to Binary28 27 26 25 24 23 22 21 20
256
128 64 32 16 8 4 2 1  1  0
22 = 10110