TODAY YOU ARE LEARNING.......

1. to explain why data is represented in computer systems in binary form

2. to understand and produce simple logic diagrams using the operations NOT, AND and OR

3. to produce a truth table from a given logic diagram.

LOGIC GATES

SOLVE THESE LOGIC PROBLEMS

http://www.think-logically.co.uk/lt.htm

Starter - http://www.logic-puzzles.org/game.php?u2=259141ce8e168b457b53b6b9d9a8bcee

Starter 2 - http://www.logic-puzzles.org/game.php?u2=a4d4c77ef9e37009fb233bf8f170a395

Further Reading http://www.ee.surrey.ac.uk/Projects/CAL/digital-logic/gatesfunc/index.html#orgate

AND GATE

Input A Input B Output (Q)

0 0

0 1

1 0

1 1

Produces an output only if both inputs are on

CAN YOU DRAW A CIRCUIT THAT WOULD ACT LIKE AN AND GATE?

OR GATEProduces an output when one or the other input are active….

Input A Input B Output (Q)

0 0

0 1

1 0

1 1

CAN YOU DRAW A CIRCUIT THAT WOULD ACT LIKE AN OR GATE?

NOT GATE

A NOT gate inverts its input

Input (A) Output (Q)

0

1

CAN YOU DRAW A CIRCUIT THAT WOULD ACT LIKE AN NOT GATE?

SOME EXTRAS TO FRY YOUR BRAIN

NAND IS AN “INVERTED AND GATE”

NOT AND = NAND

Input A Input B A.B Output (Q)=A.B

0 0

0 1

1 0

1 1

CAN YOU DRAW A CIRCUIT THAT WOULD ACT LIKE AN NAND GATE?

A NOR gate is simply an inverted OR gate. Output is high when neither input A nor input B is high:

NOT OR =NOR

Input A Input B A+B Output (Q) A+B

0 0

0 1

1 0

1 1

CAN YOU DRAW A CIRCUIT THAT WOULD ACT LIKE AN NOR GATE?

An XOR gate is constructed similarly to an OR gate, except with an additional NAND gate inserted such that

if both inputs are high, the inputs to the final NAND gate will also be high, and the output will be low.

XOR – EXCLUSIVE OR

Input A Input B Output (Q)

0 0

0 1

1 0

1 1

CAN YOU DRAW A TRUTH TABLE?

CAN YOU DRAW A TRUTH TABLE?

NOT GATE

AND GATE