How does computer work

How Do Computers Work?

Computer Basics

To accomplish a task using a computer, you need a combination of hardware, software, and input.

Hardware consists of devices, like the computer itself, the monitor, keyboard, printer, mouse and speakers. Inside your computer there are more bits of hardware, including the motherboard, where you would find the main processing chips that make up the central processing unit (CPU). The hardware processes the commands it receives from the software, and performs tasks or calculations.

Software is the name given to the programs that you install on the computer to perform certain types of activities. There is operating system software, such as the Apple OS for a Macintosh, or Windows 95 or Windows 98 for a PC. There is also application software, like the games we play or the tools we use to compose letters or do math problems.

How They Work Together

First, you provide input when you turn on the computer. Then the system software tells the CPU to start up certain programs and to turn on some hardware devices so that they are ready for more input from you. This whole process is called booting up.

The next step happens when you choose a program you want to use. You click on the icon or enter a command to start the program. Let’s use the example of an Internet browser. Once the program has started, it is ready for your instructions. You either enter an address (called a URL, which stands for Uniform Resource Locator), or click on an address you’ve saved already. In either case, the computer now knows what you want it to do. The browser software then goes out to find that address, starting up other hardware devices, such as a modem, when it needs them. If it is able to find the correct address, the browser will then tell your computer to send the information from the web page over the phone wire or cable to your computer. Eventually, you see the web site you were looking for.

If you decide you want to print the page, you click on the printer icon. Again, you have provided input to tell the computer what to do. The browser software determines whether you have a printer attached to your computer, and whether it is turned on. It may remind you to turn on the printer, then send the information about the web page from your computer over the cable to the printer, where it is printed out.

How does a computer work?

This page is created to give you a better understanding of how the personal computer works starting when you press the power button.

Powering on the computer

When you first press the power button, the computer sends a signal to the computer power supply, which converts the AC (alternating current) to DC (direct current). This power supplies the computer and its components with the proper amount of voltage and electricity.

Once the computer and its components have ample power and the power supply reports no errors, it sends a signal (using transistors) to the motherboard and the computer processor (CPU). While this is happening, the processor clears any leftover data in the memory registers and gives the CPU program counter a F000 hexadecimal number. This number tells the CPU that it’s ready to process the instructions at this location contained in the basic input/output system (BIOS).

BIOS and the POST

When the computer first looks at the BIOS, it begins the power-on self-test (POST). This sequence makes sure the necessary components are present and functioning properly. If the computer does not pass any of these tests, it encounters an irregular POST. An irregular POST is a beep code that is different from the standard one or two beeps. For example, an irregular POST could generate no beeps or a combination of different beeps to indicate the cause of the failure.

If the computer passes the POST, it looks at the first 64-bytes of memory located in the CMOS chip. This chip is kept alive by the CMOS battery even when the computer is turned off. This chip contains information such as the system time and date and information about all the hardware installed in your computer.

After loading the CMOS information, the POST begins inspecting and comparing the system settings with what is installed in the computer. If no errors are found, it loads the basic device drivers and interrupt handlers for hardware such as the hard drive, keyboard, mouse, and a floppy drive. These basic drivers allow the CPU to communicate with these hardware devices and allow the computer to continue its boot process.

Next, the POST checks the real-time clock (RTC) or system timer and the system bus to make sure both are working. Finally, you’ll get a picture on your display after the POST has loaded the memory contained on the display adapter.

Next, the BIOS checks to see if it’s performing a cold boot or warm boot (reboot) by looking at the memory address 0000:0472. If it sees 1234h, the BIOS knows that this is a reboot, and skips the remainder of the POST steps.

If 1234h is not seen, the BIOS knows that this is a cold boot and continues running additional POST steps. Next, it tests the computer memory (RAM) installed in the computer by writing to each chip. Early computers would show this step as the memory was counted during boot.

Finally, the POST sends signals to the computer optical drive and hard drive for testing. If all drives pass the test, the POST is complete and instructs the computer to start loading the operating system.

Loading the operating system

After the computer has passed the POST, it starts the boot process. This process is responsible for loading the operating system and all its associated system files. Because Microsoft Windows is the most commonly used operating system, this section covers loading Microsoft Windows.

The BIOS first hands control over to the bootstrap loader, which looks at the boot sector of the hard drive. If your boot sequence in CMOS setup is not set to look at the hard drive first, it may boot from the first available boot media (e.g., DVD or flash drive).

In this example, the Microsoft Windows 10 Bootmgr (Windows boot manager) is found on the boot sector. It tells the computer where to find the remaining code on the hard drive. Next, Windows is loaded, beginning with the Windows splash screen and loading the Windows registry. After loading the registry, Windows begins to load many low-level programs that make up the operating system into memory. Many of the initially loaded programs are what allow Windows to communicate with the essential hardware, and other programs running on the computer.

After the registry has loaded, the initial basic hardware devices, it begins to load plug and play devices, PCI, and ISA devices. After loading all these devices, Windows loads full support of the hard drive, partitions, and any other disk drives, and then moves to all other drivers that are installed.

Finally, after completing the steps above, any additional required services are loaded, and Windows starts.

Hardware devices communicating with the computer

After the computer has loaded the operating system, the hardware attached to the computer must be able to communicate with the CPU. Hardware communication is done using an interrupt request (IRQ). The interrupt controller sends the request (INTR) to the CPU to stop what it’s doing to process a new hardware request. Anything being performed by the CPU is put on hold and stored as a memory address in the memory stack. Then, that task resumes when the current (more urgent) task is completed.

What is a computer and how does it work?

Have you ever been curious about how a computer works? When I was a small child, I often wondered how any electrical device works. Whenever an electronic item went terrible in the house, I would open it and try to know its working process. During this time, I had also opened my house’s computer, but it was so complicated that I could not do anything. I did not try to understand further to avoid making it worse.

Today I know how a computer works. It is not as much complex as it looks. Some simple elements make the computer work. So, If you have ever wanted to see how the computer works, stay with me until the end. I will try my best to explain it to you as smoothly as possible.

Computer

Before proceeding, let us understand what a computer is. A computer is a machine that takes data to process it with the help of some instructions, and when the data is processed, the output it receives is often sent to the output device.

A computer is everything that can process data. A computer is used almost everywhere in today’s time. Whether you talk about a small toy or talk about the biggest airplane, in today’s time, whatever is going on with electricity, the computer is used in it.

TTL Chips

The primary component behind the working of a computer is called TTL chips. TTL chips, i.e., transistors-transistors logic integrated chips. These Integrated Chips are nothing but many combinations of different gates (AND OR XOR, etc.). If you are unfamiliar with all these gates, then don’t worry, I will explain to you further about all these gates. For the time being, you understand that it only performs some actions on whether the voltage is coming or not. This action is a fundamental rule. These simple semiconductor transistors give a pre-based output. These gates work on a binary system logic, i.e., a number system with only two numbers, the first number is 0, and the second number is 1.

With the help of binary numbers, we can convert almost every electrical signal into a digital signal. Using two voltage parameters(generally 0V ), we convert analog signals into digital signals. The computer works on the digital signal. These digital signals use switches. Switches only have two possibilities, either it will be in OFF state or ON state. OFF and ON are represented using two numbers i.e., 0 and 1, respectively.

Main Components of a Computer

So let’s talk about a computer. There are about three main things on a computer.

CPU means the central processing unit. CPU contains a lot of small circuits with a specialized purpose. These circuits are made up of logic gates. It performs small operations such as addition, subtraction, multiplication, division, store, fetch, Output, etc. But the thing to understand is that, how does the CPU know which operation to perform?

To know how the CPU knows which operation to perform, We need to see the sent instructions. Instruction is a predetermined sequence of binary numbers. Every sequence is mapped to a particular circuit.Whenever an instruction comes to the CPU, the CPU checks the corresponding operation to the binary series.

Memory

Now let’s talk about the second component of the computer, which is memory. Memory is used to store any type of data. Memory is of two kinds. The first memory is Volatile memory. Volatile memory is a memory that wipes its data when the computer shuts down. The second memory is Non-volatile memory. Non-volatile memory retains data even if the computer turns off.

RAM is a type of volatile memory. Whenever a computer wants to run a program, it first stores it in the main memory(RAM) and then runs it. CPU does this because the RAM is more high-speed than any Secondary storage. To do this, it takes the help of the operating system. The operating system manages memory. When these programs complete their execution, the output is saved in permanent storage devices.

ROM means read-only memory. Understandably, this memory cannot be written. ROM provides programs to start the computer. ROM helps at the starting of a computer and loads the operating system.

Secondary Memory

Secondary memory is a non-volatile storage device. This type of memory is used to store data permanently. It holds files of the operating system, user applications, personal files, and other storage purposes. This type of storage is significant, cheap, and reliable. Hard Disks, SSDs, USB drives, Optical disks are some examples of secondary memory.

Software

The third component is the software. Software is a collection of small programs. The most important software are :

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So how do computers actually work?

A high-level overview of how binary numbers make computers work for curious non-technical people.

How computers work is something that I’ve always been curious about but never actually thought that I was going to have the actual basic knowledge to understand it, even at a high level. So doing the research to write this blog post and finding out that it wasn’t so hard to understand has been very rewarding, plus, getting to understand how computers work, again even at a high level, is pretty mind-blowing.

The most basic way of thinking of a computer is as an Input/Output machine. That’s a pretty basic idea: computers take information from external sources (your keyboard, mouse, sensors or the internet), store it, process it, and return the result (Output) of that process. By the way, if you think about it, the moment computers are connected through the internet there’s an ever ending loop of inputs and outputs as the output of a computer (say a website) becomes the input of another and so forth(!!).

Now, we are all pretty used and familiar with the ways a computer has to receive input and to print out some output, we’ve all used a mouse or a keyboard, or even talked to a computer and we’ve all read an article on a website, listened to music or browsed through some old pictures, etc. What we ain’t as familiar with, and what we usually struggle to understand is how a computer actually processes information.

So how does the binary number system works? Binary numbers mean that all numbers are computed with base 2. As an example, most of us are used to think of numbers with base 10. If you think about any number, let’s say 2561, you can see how depending on the position the number occupies from right to left, the number has a different value which is a multiple of ten. In this example, for instance, 1 occupies the 1s position, 6 occupies the 10s position, 5 occupies the 100s position and 2 occupies the 1000’s position. This way, (2×1000) + (5×100) + (6×10) + (1×1) = 2561. Binary numbers work in the exact same way but every incremental step represents an x2 increment over the previous one. Here’s an example of how to represent number 12:

So, with 8 bits you can represent any number between 0 and 255, and with 32 bits you can represent any number between 0 and 4 billion. You might be thinking, sure but what about strings and punctuation? Well, as of today, we still follow the ASCII, American Standard Code for Information Interchange that basically maps any character or punctuation sign including capital letters to one of the 8-bit numbers. And this is how we use numbers to represent letters.

Sure, but what about images? Well, actually an image can also be reduced to 0’s and 1’s. As you know, any screen has a given number of pixels and every pixel has a color and as you know, using RGB or HEX color codes we can represent colors as numbers which means that we can basically tell a computer which color each pixel must have. The same thing goes for music, video and any other type of information you can think of.

But how the hell do we “compute” electric signals? That is where electrical circuits come in. On a very basic and oversimplified level, we can use electrical circuits to behave as “logical machines”. We can have circuits that, given a specific input, will return an output depending on the logic with which they’ve been built (Not, And, Or) but also sums, subtractions, multiplications, and divisions. The interesting part is that using these very elemental forms of representing and processing information we can actually achieve “functional completeness” which is a term used in Logic to refer to a set of boolean operators which are able to represent all possible truth tables, which is a fancy way that mathematicians have to say that sky is the limit. All these calculations happen in a unit inside your CPU called ALU (Arithmetic Logic Unit).

As you probably know CPU’s — Central Processing Unit — are the brains of computers and it’s where all the computation happens. The interesting part about CPU’s is that they don’t have any memory which means that they can’t remember absolutely anything. Without memory, every computation would be lost right after we perform it. Roughly speaking, and as you might already know, there are two types of memory our computers use: RAM which stands for Random Access Memory and Persistent Memory. You can think of RAM memory as an immense grid (matrix) storing 8-bit numbers. RAM memory keeps track of the “addresses” in the memory matrix of any given 8-bit number for whenever the CPU needs it. And guess what? In order to perform these operations, we use the exact same circuit logic that we used before. This is, we use the exact same logic to allow a given input to be stored in a given “place” in the memory or to access whatever piece of information stored in it.

I know that I am barely scratching the surface of how computers work here, but just getting to understand this has taken me quite some time and has already blown my mind more than a few times. What fascinates me about this is how powerful computers are and how embedded they are in our everyday lives, this is why I think it’s important to at least have an intuition of how they work. Also, as always, if you spot any mistake please let me know.

I’ll finish this post with a video that I really like where Steve Jobs compares computers to bicycles here:

Here’s a list of amazing resources I’ve found while doing some research for this post:

How PCs Work

By: Jeff Tyson & Stephanie Crawford | Updated: May 12, 2021

The word computer refers to an object that can accept some input and produce some output. In fact, the human brain itself is a sophisticated computer, and scientists are learning more about how it works with each passing year. Our most common use of the word computer, though, is to describe an electronic device containing a microprocessor.

A microprocessor is a small electronic device that can carry out complex calculations in the blink of an eye. You can find microprocessors in many devices you use each day, such as cars, refrigerators and televisions. The most recognized device with a microprocessor is the personal computer, or PC. In fact, the concept of a computer has become nearly synonymous with the term PC.

When you hear PC, you probably envision an enclosed device with an attached video screen, keyboard and some type of a pointing device, like a mouse or touchpad. You might also envision different forms of PCs, such as desktop computers, towers and laptops. The term PC has been associated with certain brands, such as Intel processors or Microsoft operating systems. In this article, though, we define a PC as a more general computing device with these characteristics:

While the Altair 8800 was the first real personal computer, it was the release of the Apple II a couple of years later that signaled the start of the PC as a sought-after home appliance. The Apple II, from inventors Steve Jobs and Steve Wozniak, proved that there was a demand for computers in homes and schools. Soon after, long-established computer companies like IBM and Texas Instruments jumped into the PC market, and new brands like Commodore and Atari jumped into the game.

In this article, we’ll look inside the PC to find out about its parts and what they do. We’ll also check out the basic software used to boot and run a PC. Then, we’ll cover mobile PCs and examine the future for PC technology.

Core PC Components

To see how a PC works, let’s start with the pieces that come together to make up the machine. The following are the components common to PCs in the order they’re typically assembled:

A PC is typically much more than these core components. Next, we’ll look at the ports and peripherals that let you interact with the computer and how you can add even more components using expansion slots.