1. Basic Digital Logic 2 Combinational Logic
Created for the Western Canadian Robotics Society
Paul Godin
February 2004

2. Basic Digital Logic 2
Review

3. Review Digital Electronics makes use of 2 states: Logic High, or “1”
Logic Low, or “0”

4. Review
There are 3 basic digital gates:
AND OR
NOT

5. Review AND, where ALL inputs must be “1” for the output to be “1”
OR, where ANY of the inputs can be “1” for the output to be “1”
NOT (or the Inverter) where the output is the opposite (compliment) of the input.

6. Review Questions
What is the outcome of the following: 1 1 1 1 1

7. Basic Combinational Logic, NAND and NOR gates
Basic Digital Logic 2
Basic Combinational Logic, NAND and NOR gates

8. Combinational Logic
A circuit that utilizes more that 1 logic function has Combinational Logic.
As an example, if a circuit has an AND gate connected to an Inverter gate, this circuit has combinational logic.

9. Combinational logic
How would your describe the output of this combinational logic circuit?

10. NAND Gate
The NAND gate is the combination of an NOT gate with an AND gate.
The Bubble in front of the gate is an inverter.

11. Combinational logic
How would your describe the output of this combinational logic circuit?

12. NOR gate
The NOR gate is the combination of the NOT gate with the OR gate.
The Bubble in front of the gate is an inverter.

13. NAND and NOR gates
The NAND and NOR gates are very popular as they can be connected in more ways that the simple AND and OR gates.

14. Exercise 1 – a bit challenging
Complete the Truth Table for the NAND and NOR Gates
NAND
NOR
Input
Output 1
Input
Output 1
Hint: Think of the AND and OR truth tables. The outputs for the NAND and NOR are inverted.

15. Exercise 2 – more challenging
Turn the NAND and NOR gates into inverter (NOT) gates. Include a switch for the input.

16. Basic Digital Logic 2
Chips and Gates

17. Basic Digital Chips
Digital Electronics devices are usually in a chip format.
The chip is identified with a part number or a model number.
A standard series starts with numbers 74, 4, or 14.
7404 is an inverter
7408 is an AND
7432 is an OR
4011B is a NAND

18. Chips Basic logic chips often come in 14-pin packages.
Package sizes and styles vary.
Pin 1 is indicated with a dot or half-circle
Numbers are read counter-clockwise from pin 1 (viewed from the top)
Pin 14
Pin 8
Pin 1
Pin 7

19. Chips Chips require a voltage to function
Vcc is equal to 5 volts and is typically pin 14
Ground is typically pin 7
Pin 14
Pin 8
Pin 1
Pin 7

20. Chips – Specification Sheet
Voltage
The voltage and ground pins must be connected for the device to function. Check the specification sheet to make sure.
Ground
Diagram from

21. Chips – Specification SheetB C D
Diagrams from

22. Wiring a chip IN
Vcc IN
OUT
Probe
Vcc

23. Useful Resources Textbooks on Digital Electronics (used is ok!)
Electronics Workbench or other electronic simulation software
Craig Maynard’s Virtual Vulcan
The following web sites:

24. Lab Exercise
Using the experimenter’s boards, connect the circuit provided to you in the following pages.

25. Layout of the SK-10 Experimenter's Board

26. Layout of the SK-10 Experimenter's Board
Flat Side
7400
Wires

27. Logic Diagram of Lab

28. End of Basic Digital Logic 2
Copyright WCRS and Paul Godin
For non-profit use only