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What is a computer? A computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve, and process data. You may already know that you can use a computer to type documents, send email, play games, and browse the Web. You can also use it to edit or create spreadsheets, presentations, and even videos.

  • Hardware is any part of your computer that has a physical structure, such as the keyboard or mouse. It also includes all of the computer's internal parts, which you can see in the image below.

Before we talk about different types of computers, let's talk about two things all computers have in common: hardware and software.

Hardware vs. software

Everything you do on your computer will rely on both hardware and software. For example, right now you may be viewing this lesson in a web browser (software) and using your mouse (hardware) to click from page to page. As you learn about different types of computers, ask yourself about the differences in their hardware. As you progress through this tutorial, you'll see that different types of computers also often use different types of software.

  • Software is any set of instructions that tells the hardware what to do and how to do it. Examples of software include web browsers, games, and word processors.

When most people hear the word computer, they think of a personal computer such as a desktop or laptop. However, computers come in many shapes and sizes, and they perform many different functions in our daily lives. When you withdraw cash from an ATM, scan groceries at the store, or use a calculator, you're using a type of computer.

What are the different types of computers?

Many people use desktop computers at work, home, and school. Desktop computers are designed to be placed on a desk, and they're typically made up of a few different parts, including the computer case, monitor, keyboard, and mouse.

  • Desktop computers

The second type of computer you may be familiar with is a laptop computer, commonly called a laptop. Laptops are battery-powered computers that are more portable than desktops, allowing you to use them almost anywhere.

  • Laptop computers

A server is a computer that serves up information to other computers on a network. For example, whenever you use the Internet, you're looking at something that's stored on a server. Many businesses also use local file servers to store and share files internally.

  • Servers

Since the evolution of humans, devices have been used for calculations for thousands of years. One of the earliest and most well-known devices was an abacus. Then in 1822, the father of computers, Charles Babbage began developing what would be the first mechanical computer. And then in 1833 he actually designed an Analytical Engine which was a general-purpose computer. It contained an ALU, some basic flow chart principles and the concept of integrated memory. Then more than a century later in the history of computers, we got our first electronic computer for general purpose. It was the ENIAC, which stands for Electronic Numerical Integrator and Computer. The inventors of this computer were John W. Mauchly and J.Presper Eckert. And with times the technology developed and the computers got smaller and the processing got faster. We got our first laptop in 1981 and it was introduced by Adam Osborne and EPSON.

  • History

Powering on the computer Computer power supply 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).

  • How does a computer work?

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 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.

  • Famous Computer Scientists

Loading the operating system Windows 10 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.

Tim Berners-Lee Sir Timothy John Berners-Lee, a.k.a. Tim BL, was a well-known computer scientist from England. Initially, he worked as a researcher at CERN, the European Organization for Nuclear Research. Later, Tim became a Fellow of Computer Science at the University of Oxford. Currently, he is a professor at the Massachusetts Institute of Technology (MIT). Important contributions and achievements Tim BL invented the World Wide Web (WWW). Tim BL was awarded the Knighthood by Queen Elizabeth II. He invented the three major requirements of WWW: Hypertext Transfer Protocol (HTTP), Uniform Resource Locator(URL), and Hypertext Markup Language (HTML). He launched the first website http:// info.cern.ch. He co-founded the World Wide Web Foundation. He founded the World Wide Web Consortium at the Massachusetts Institute of Technology.

Ray Tomlinson Raymond Samuel Tomlinson was an American computer programmer. His work helped users to transmit messages on different computers. Tomlinson invented the Transmission Control Protocol (TCP), one of the main protocols of the Internet protocol suite. Important contributions and achievements Tomlinson invented email on the ARPANET system. ARPANET is the forerunner of the Internet. Tomlinson created the @ sign symbol to connect the username with the destination address. He received the Computer Pioneer Award from the American Computer Museum. Tomlinson was the first person to write a file transfer program called CPYNET to transfer files through the ARPANET.