How Computers Work

Do you want to know how does a computer work? Students and those who want to get into the repair business will find this article on how computers work really useful.

A computer, though it looks very compact and simple nowadays, it is still a complicated piece of equipment. At the most basic level, it takes information input into the CPU, or central processing unit, and then outputs information and solutions to the user.

When you turn on the computer, the system software tells the CPU to start certain programs and some hardware devices so that they are ready for more input from you. This whole process is called booting up (short for bootstrap). The boot process is controlled by the PC’s basic input-output system (BIOS), read more.

But then there is a lot more to it.

Just take a look inside of your computer, in case you get the opportunity to do so, and you will see that it is basically several transistors working together in a microprocessor, to add numbers and do other calculations, and make decisions. In addition, we’ll also talk about processor design, what a logic gate is, how a computer does math logic, and all the basics of digital design, that goes into making of a processor.

If you’ve always been curious about how computers really work, and if you’re interested in logic circuits, here’s a video that explains the theory behind how computers count and how you can build your own 4-bit computer using logic gates. which are made of individual transistors.

How Does a Computer Work?

A computer is made of several components, but then how do these components work with each other? What exactly happens when you press the power button?

BIOS in Action
Here is the sequence of steps that happen when the power to the computer is switched on.

1. The motherboard gets power from the power supply.
2. The BIOS (software associated with the processing chip) then checks all the hardware components. If new hardware has been recently added, the relevant drivers are installed for that component.
3. The BIOS then starts loading all of the necessary components, such as the video card, sound card, keyboard, mouse and RAM
4. The BIOS initializes the operating system.
5. Once all the hardware and software checks are done, the operating system (OS) takes over.

So are you ready to use the computer now?

Not yet! The operating system has its own sets of tests and things to be loaded. Only after that you can start working on the computer.

Operating system (OS) in Action
So what does the OS do?

It basically manages the processor, memory, devices, storage and other applications.

Whenever you want to work with any application such as Word or Excel, it’s the operating system that checks for the program and loads it.

As you can see, to the end user, it might seem to be an easy task using the various applications, but it is all made easy due to the coordination between the various parts within the computer.

How Does a Computer Boot?

Knowing how a computer boots can help you to pinpoint problems if your computer is not starting in the normal manner.

Do you really need to know how a computer boots? Not really! In fact, you won’t even bother about it till your computer is working fine.

But the moment your computer faces any problem, or is hit by a malware, and is not working properly, it helps to know how it boots so that you can pin point the exact problems.

Here are the basic steps in the boot process for a computer.

CPU in Action
When the power comes on, the CPU searches for one simple instruction that will tell the system to go to the BIOS to allow it to start up.

This instruction is usually referred to as a jump.

In other words, the CPU turns on and finds the jump instruction in order to allow the BIOS to begin doing its job.

POST: power-up self test
Without this process, the computer will not be able to boot and would not work.

POST is exactly what it stands for: power-up self test.

There are certain devices that are needed to continue the boot process, and the POST tests these devices for reliability. Once tested, and if working properly, these devices are started up.

This power-up self test is completed by the BIOS.

Bootable Devices
After the POST is successfully completed, the BIOS then searches for a bootable device so that the operating system starts. Usually this is located on the hard drive, but it can be located on any device.

The BIOS will continue to search till it finds one, in case nothing is found you will get an error message and your computer will not boot up.

Master Boot Record
The hard disk drive is made of several partitions. A master boot record (MBR) is a partition which holds the remaining information required to start the computer (boot it up).

The master boot record is also known as the boot sector. Inside the MBR is a special piece called the kernel, or the operating system kernel.

This contains all the information necessary for the operating system to load and start doing all the tests.

This is how a computer works.