All to know about Computers

To be fair, computers have changed enormously considering 6 decades ago. In the 1940s, they were giant scientific and military behemoths commissioned by the government at a cost of millions of dollars per computer; today, most computers are not even recognizable as such: they are embedded in everything from cellphones to microwaves and digital radios. What makes computers flexible enough to work in all these different appliances? How come they are so phenomenally useful? And how exactly do they work? Let's take a closer look!

What is a computer?

A computer is an electronic machine that processes information—in other words, an information processor: it takes in raw information (or data) at one end, stores it until it's ready to work on it, chews and crunches it for a bit, then spits out the results at the other end. All these processes have a name. Taking in information is called input, storing information is better known as memory (or storage), chewing information is also known as processing, and spitting out results is called output.

Imagine if a computer were a person. Suppose you have a friend who's really good at math. She is so good that everyone she knows posts their math problems to her.  Each morning, she goes to her letterbox and finds a pile of new math problems waiting for her attention. She piles them up on her desk until she gets around to looking at them. Each afternoon, she takes a letter off the top of the pile, studies the problem, works out the solution, and scribbles the answer on the back. She puts this in an envelope addressed to the person who sent her the original problem and sticks it in her out tray, ready to post. Then she moves to the next letter in the pile. You can see that your friend is working just like a computer. Her letterbox is her input; the pile on her desk is her memory; her brain is the processor that works out the solutions to the problems; and the out  tray on her desk is her output.

Once you understand that computers are about input, memory, processing, and output, all the junk on your desk makes a lot more sense:

• Input: Your keyboard and mouse, for example, are just input units—ways of getting information into your computer that it can process. If you use a microphone and voice recognition software, that's another form of input.
• Memory/storage: Your computer probably stores all your documents and files on a hard drive: a huge magnetic memory. But smaller, computer-based devices like digital cameras and cellphones use other kinds of storage such as flash memory cards.
• Processing: Your computer's processor (sometimes known as the central processing unit) is a microchip buried deep inside. It works amazingly hard and gets incredibly hot in the process. That's why your computer has a little fan blowing away—to stop its brain from overheating!
• Output: Your computer probably has an LCD screen capable of displaying high-resolution (very detailed) graphics, and probably also stereo loudspeakers. You may have an inkjet printer on your desk too to make a more permanent form of output.

What is a computer program?

The first computers were gigantic calculating machines and all they ever really did was "crunch numbers": solve lengthy, difficult, or tedious mathematical problems. Today, computers work on a much wider variety of problems—but they are all still, essentially, calculations. Everything a computer does, from helping you to edit a photograph you've taken with a digital camera to displaying a web page, involves manipulating numbers in one way or another.

Suppose you're looking at a digital photo you just taken in a paint or photo-editing program and you decide you want a mirror image of it (in other words, flip it from left to right). You probably know that the photo is made up of millions of individual pixels (colored squares) arranged in a grid pattern. The computer stores each pixel as a number, so taking a digital photo is really like an instant, orderly exercise in painting by numbers! To flip a digital photo, the computer simply reverses the sequence of numbers so they run from right to left instead of left to right. Or suppose you want to make the photograph brighter. All you have to do is slide the little "brightness" icon. The computer then works through all the pixels, increasing the brightness value for each one by, say, 10 percent to make the entire image brighter. So, once again, the problem boils down to numbers and calculations.

What makes a computer different from a calculator is that it can work all by itself. You just give it your instructions (called a program) and off it goes, performing a long and complex series of operations all by itself. Back in the 1970s and 1980s, if you wanted a home computer to do almost anything at all, you had to write your own little program to do it. For example, before you could write a letter on a computer, you had to write a program that would read the letters you typed on the keyboard, store them in the memory, and display them on the screen. Writing the program usually took more time than doing whatever it was that you had originally wanted to do (writing the letter). Pretty soon, people started selling programs like word processors to save you the need to write programs yourself.

Today, most computer users rely on prewritten programs like Microsoft Word and Excel or download apps for their tablets and smartphones without caring much how they got there. Hardly anyone writes programs any more, which is a shame, because it's great fun and a really useful skill. Most people see their computers as tools that help them do jobs, rather than complex electronic machines they have to pre-program. Some would say that's just as well, because most of us have better things to do than computer programming. Then again, if we all rely on computer programs and apps, someone has to write them, and those skills need to survive. Thankfully, there's been a recent resurgence of interest in computer programming. "Coding" (an informal name for programming, since programs are sometimes referred to as "code") is being taught in schools again with the help of easy-to-use programming languages like Scratch. There's a growing hobbyist movement, linked to build-it yourself gadgets like the Raspberry Pi and Arduino. And Code Clubs, where volunteers teach kids programming, are springing up all over the world.