1. Computer Fundamentals
Northern College Diploma
Philip Bird

2. Bits and Bytes
Computers work with on’s and off’s – Binary digital values 0 and 1.
Binary digits (bits) are usually organised into groups of 8 – a byte.
We can use a byte to represent a whole number (integer), a fraction (real) and a character.
We can also represent negative numbers.

3. Converting to Binary Base4 Base3 Base2 Base1 Base0 10000 1000 100 10 1
Decimal 16 8 4 2
Binary

4. Converting from Binary16 8 4 2 1
= 13 = 22

5. Binary Addition
128 64 32 16 8 4 2 1
=102
=117 1 1 1 1 1 1 1 1 1
=219

6. Storing Characters
128 64 32 16 8 4 2 1
=65 ‘A’
=97 ‘a’
=43 ‘+’

7. Storing Negative Numbers
-128 64 32 16 8 4 2 1
=38
=-90
=127
=-128

8. Storing Fractions
1/2
1/4
1/8
1/16
1/32 1
=13/16
=23/32

9. Logic Gates Used to process the binary digits.
Originally made as valves, then transistors then integrated into circuits on a chip.
History of smaller, faster, denser, cheaper.
Each gate governed by a rule.

10. NOT Gate In Out 1 NOT 1 1 Rule:1
NOT 1 1
Rule:
The output is the opposite of the input.

11. AND Gate In1 In2 Out 1 1 1 AND Rule:1 1 1
AND
Rule:
The output is 1 if all the inputs are 1.

12. OR Gate In1 In2 Out 1 1 1 OR Rule:1 1 1 OR
Rule:
The output is 1 if any of the inputs are 1.

13. XOR Gate In1 In2 Out 1 1 1 XOR Rule:1 1 1
XOR
Rule:
The output is 1 if either of the inputs are 1 but not both.

14. Summary Why do computers use binary? What can be stored in binary?
What is a logic gate used for?