Showing posts with label Computers. Show all posts
Showing posts with label Computers. Show all posts

Thursday, January 31, 2013

Binary


When we talk about letters and words, we know that A is a letter,
and Apple is a word with the letters A, p, p, l, e.

For numbers, instead of saying letters we call them digits So the number 174 has the digits 1, 7, 4.

The numbers we use every day go from 0 to 9.
The digits are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
(The number 10 uses the digits 1 and 0.)

Since there are ten digits, we use the word decimal.

What if we only had two digits to use, 0 and 1?

Could we still make numbers?
Yes!

We can make the numbers: 0, 1, 10, 11, 100, 101, 110, 111 and so on!
Since we're only using 2 digits, we use the word binary (like bicycle which has two wheels)

When we want to match up our decimal numbers to our binary numbers,
we just put them in the same order.

binary 0, 1, 10, 11 is the same as decimal 0, 1, 2, 3
So b0 = d0, b1 = d1, b2 = d10, b3 = d11 and so on!

We already learned about how computers use 1 and 0 to turn lights on and off on your computer screen.

The whole computer uses just binary numbers to do all the math to turn those switches on and off.

Just think, giving a computer a number like: 1110 can be like telling it to turn 3 lights on, and the other one off!

Thursday, January 24, 2013

And Or logic gates


Last time we learned about true and false
and how they worked in computers like On and Off switches
turning thousands of light bulbs on and off.

light bulb
(from: wikipedia - incandescent light bulb)

Now think about what would happen if you had two light switches
called switch A and switch B,
and they were hooked up to the same light bulb.

light switch light switch
(from: wikipedia - light switch)

Would you have to have both switches set to ON for it to turn on?
Or is just one good enough?

In computers and electronics, we call that using AND and OR.
So if you need both light switches ON to turn on one light bulb,
that means you need A AND B on.

If the light will turn ON with either switch,
that means A OR B.

When people draw out the AND and OR in pictures,
they sometimes call them logic gates. There are different pictures for an AND gate and an OR gate.

The AND gate sort of looks like a big letter D.
and
(from: wikipedia - and gate)

The OR gate sort of looks like a spaceship!
OR
(from: wikipedia - OR)

Using those logic gates like switches to turn on and off light bulbs,
you can draw up big pictures that can be used as instructions for building a computer!
alu
(from: wikipedia - logic diagram)

Thursday, January 17, 2013

Boolean True False


You probably already know this, but True is a way of saying Yes.
and False is the opposite and means No.

A fancy word for True and False is Boolean
named after the famous mathemetician George Boole.

In computers and electronics, it's kind of like you're looking at a light bulb.
If the light bulb is ON, you can call that True or Yes or even the number 1.
Is the light bulb is OFF, you can call it False or No or the number 0.
light bulb
(from: wikipedia - light bulb)

Inside computers the electricity that runs the computer has thousands
or even millions of little ones and zeroes, meaning True and False.

These little light bulbs are what make the pictures on your computer screen
and the light switches come from things like your keyboard and mouse.

You can imagine a room just filled with light bulbs and light switches,
and that's exactly what some of the oldest computers (like the ENIAC) looked like!
eniac
(from: wikipedia - eniac)

Thursday, November 15, 2012

USB


USB stands for Universal Serial Bus

It's the name of a type of connector for computers, to connect phones, computers, cameras, and just about anything else!

This is what a USB port looks like on a computer:



And this is what a USB cable looks like:

(from: wikipedia - usb)

Thursday, October 4, 2012

Hardware & Software


For computers, the word hardware means all of the hard parts of the computer, like the screen, buttons, keyboards, all the bits and pieces inside a phone or laptop or desktop computer.

computer hardware
(From: Wikipedia - Personal Computer Hardware)

The word software means all of the things that the computers do, like games and programs that run and make the computer work.

Angry Birds

(From: Wikipedia - Angry Birds)

Thursday, September 27, 2012

ENIAC


The first computer was called the ENIAC.
(Sounds like Any-Ack) It stands for a bunch of big words that just mean it was a big math calculator:
Electronic Numerical Integrator And Computer

eniac
(From: Wikipedia - eniac)

It wasn't like any of the fancy computers we have now with big colored touch screens!
It was a whole room full of wires and lights and could only do math problems with numbers.
This might not seem like much, but it could figure out over 350 problems like this in less than a second.
Way faster than most humans!

9,292,532,154 x 2,135,484,354 = 19,844,057,023,908,918,516