Logic Gates (report).pptx

7/30/2019 Logic Gates (report).pptx

1/19


2/19

an electronic component that is

capable of directing the flow ofelectricity in a circuit, based on

signals from the computer that

corresponds to logical relationships,

such as AND, NOT, and OR.


3/19

A logic gate receives two

incoming electric currents,

compares them, and then sends it

on a new, outgoing electric current

depending on what it finds.

A logic gate is a bit like a doorman

or bouncer who is allowed to let

people into a nightclub only if they

pass certain tests.


4/19


5/19

TRUTH TABLEInput

OutputA B

0 0 0

0 1 0

1 0 0

1 1 1


6/19

Suppose you go to a nightclub where the doorman's

job is to enforce a simple rule: "Everyone in your

group must wear a tie to come in". You go along witha friend one night. If you're both wearing ties, you'll

get in. If only one of you is wearing a tie, or if neither

of you is, neither of you will get in. An AND logic gate

works the same way with two electrical inputs. If

both inputs are switched on (that is, carry a number

1), the output will be 1 as well. Otherwise the output

will be 0.


7/19

TRUTH TABLE

Input Output

0 1

1 0


8/19

So far, you've failed to get into either of the clubs. But there's one

last hope: you know a friend is having a party a few streets away.

The only trouble is, there's a really argumentative and contrary

person on the door. He talks to each person in turn as they

approach him. If you're nice and polite, he shouts abuse at you

and turns you away. But if you're rude to him, he likes that for

some reason and lets you in. In other words, he does exactly the

opposite of what you'd expect! In electronics, there's a logic gatethat works in the same, contrary way and it's called a NOT gate or

invertor. Unlike AND and OR gates, it has only one input and one

output. The output is exactly the opposite of the input, so if the

input is a 0, the output is a 1 and vice versa.


9/19

TRUTH TABLE

InputOutput

A B

0 0 00 1 1

1 0 1

1 1 1


10/19

You're not wearing a tie, so you go to another club

further down the street. Here, the person on the door is

enforcing a different rule: "A group of people can comein if any one of them is a member". If either you or your

friend is a member, or if you both are members, you can

both come in. If neither of you is a member, you're both

left out in the cold. An OR logic gate works this way withtwo electrical inputs. If either input is switched on (that

is, carries a number 1), the output will be 1 as well.

Otherwise the output will be 0.


11/19


12/19

NAND is just like AND,

only the end result isswapped over (so where

AND produces an output

of 1, NAND produces an

output of 0).


13/19

NOR is like OR

with the end

result swapped

over in the same

way.


14/19

XOR (Exclusive OR)is like an OR, but it

switches off if

both the inputs

are switched on.


15/19

Calculators use different

combinations of logic gates. Logic

gates controls how the displayworks in a calculator figures out

the results of calculations.

Calculators


16/19

Each segment of

the display is

switched on and

off by a series of

logic gates that

are connectedtogether.


17/19

Consider this as an example.

* The other six segments of each digit are controlled

by other combinations of logic gates.


18/19


19/19

Logic Gates (report).pptx

Documents

Transcript of Logic Gates (report).pptx