COMPUTER HARDWARE PART

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A computer monitor an output device which displays information in pictorial form. A monitor usually comprises the display device, circuitry, casing, and power supply.

Basically there are 3 types of monitors-:

CRT (cathode ray tube) monitors. (As shown in pic 1)

These monitors employ CRT technology, which was used most commonly in the manufacturing of television screens. With these monitors, a stream of intense high energy electrons is used to form images on a fluorescent screen. A cathode ray tube is basically a vacuum tube containing an electron gun at one end and a fluorescent screen at another end.

While CRT monitors can still be found in some organizations, many offices have stopped using them largely because they are heavy, bulky, and costly to replace should they break. While they are still in use, it would be a good idea to phase these monitors out for cheaper, lighter, and more reliable monitors.

LCD (liquid crystal display) monitors(As shown in pic 2)

The LCD monitor incorporates one of the most advanced technologies available today. Typically, it consists of a layer of color or monochrome pixels arranged schematically between a couple of transparent electrodes and two polarizing filters. Optical effect is made possible by polarizing the light in varied amounts and making it pass through the liquid crystal layer. The two types of LCD technology available are the active matrix of TFT and a passive matrix technology. TFT generates better picture quality and is more secure and reliable. Passive matrix, on the other hand, has a slow response time and is slowly becoming outdated.

LED (light-emitting diodes) monitors (As shown in pic 3)

LED monitors are the latest types of monitors on the market today. These are flat panel, or slightly curved displays which make use of light-emitting diodes for back-lighting, instead of cold cathode fluorescent (CCFL) back-lighting used in LCDs. LED monitors are said to use much lesser power than CRT and LCD and are considered far more environmentally friendly.

The advantages of LED monitors are that they produce images with higher contrast, have less negative environmental impact when disposed, are more durable than CRT or LCD monitors, and features a very thin design. They also don’t produce much heat while running. The only downside is that they can be more expensive, especially for the high-end monitors like the new curved displays that are being released.

A computer's CPU handles all instructions it receives from hardware and software running on the computer.processor, central processor, or microprocessor, the CPU (pronounced sea-pea-you) is the central processing unit of the computer.

CPU

Stands for "Central Processing Unit." The CPU is the primary component of a computer that processes instructions. It runs the operating system and applications, constantly receiving input from the user or active software programs. It processes the data and produces output, which may stored by an application or displayed on the screen.

The CPU contains at least one processor, which is the actual chip inside the CPU that performs calculations. For many years, most CPUs only had one processor, but now it is common for a single CPU to have at least two processors or "processing cores." A CPU with two processing cores is called a dual-core CPU and models with four cores are called quad-core CPUs. High-end CPUs may have six (hexa-core) or even eight (octo-core) processors. A computer may also have more than one CPU, which each have multiple cores. For example, a server with two hexa-core CPUs has a total of 12 processors

Keyboard

A computer keyboard is one of the primary input devices used with a computer. Similar to an electric typewriter, a keyboard is composed of buttons that create letters, numbers, and symbols, as well as perform other functions. The following sections provide more in-depth information and answers to some of the more frequently asked questions about the keyboard.

Keyboard overview

The following image shows a 104-key Saitek keyboard with arrows pointing to each section, including the control keys, function keys, LED indicators, wrist pad, arrow keys, and keypad.

QWERTY keyboard layout

Below is a close up image of a QWERTY computer keyboard with each of the keys selectable. You may hover your mouse cursor over any of the keys to see a description. Clicking any of the keys opens a new page with full details.

• Computer keyboard key explanations.

Keyboard ports and interfaces

Today, most desktop computer keyboards connect to the computer using either USB or Bluetooth for wireless communication. Before USB, a computer may have used PS/2, serial port, or AT (Din5) as a keyboard interface.

• How to connect and install a keyboard.

Types of keyboards

Today, most keyboards are similar to each other, but may be missing one or more of the sections mentioned earlier (e.g., the keypad). Where keyboards begin to differ the most is with their constructions. Some keyboards are mechanical, while others use membrane keys. Some keyboards are split down the middle and others even fold in half or roll up. While most keyboards use the QWERTY layout, there are still people who use the DVORAK layout.

Laptop keyboards

A laptop keyboard is arranged differently than a desktop keyboard to accommodate the laptop's narrower footprint. Most laptop keyboards are made smaller by placing the keys closer and by including an Fn key. The Fn key is used in conjunction with other keys to perform special functions. For example, pressing the Fn key and the up or down arrow on the keyboard shown below, increases and decreases the brightness of the screen. Furthermore, many laptop keyboards omit the numeric keypad to save space.

Smartphone and tablet keyboards

Today's smartphones and tablets do not come with a physical keyboard, although it may be purchased as an optional peripheral add-on. These devices utilize a thumb keyboard or on-screen keyboard to type messages and enter text into various fields. The image is an example of the Apple iPhone on-screen keyboard, used on all Apple touch-based devices.

Why is the keyboard an input device?

A computer keyboard is considered an input device because it only sends data to a computer and does not receive any information back.

What are multimedia keys?

Multimedia keys are those keys which allow the user to control music on their computer keyboard. These keys add functionality such as play, pause, stop, rewind, fast-forward, skip track, eject, shuffle, and repeat.

Computer mouse

A computer mouse is a handheld hardware input device that controls a cursor in a GUI (graphical user interface) and can move and select text, icons, files, and folders on your computer.

For desktop computers, the mouse is placed on a flat surface (e.g., mouse pad or desk) in front of your computer. The picture is an example of a desktop computer mouse with two buttons and a wheel.

Who invented the mouse?

The mouse was originally known as the X-Y Position Indicator for a Display System and was invented by Douglas Engelbart in 1963 while working at Xerox PARC. But, due to Alto's lack of success, the first widely used application of the mouse was with the Apple Lisa computer. Today, this pointing device is on virtually every computer.

What are the uses of a mouse?

Below is a list of computer mouse functions to give you an idea of all the things a mouse is capable of doing.

1. Move the mouse cursor - The primary function is to move the mouse pointer on the screen.
2. Open or execute a program - Once you've moved the pointer to an icon, folder, or other object clicking or double clicking that object opens the document or executes the program.
3. Select - A mouse also allows you to select text or a file or highlight and select multiple files at once.
4. Drag-and-drop - Once something is selected, it can also be moved using the drag-and-drop method.
5. Hover - Moving the mouse cursor over objects with hover information can help discover the function of each object on the screen. For example, hover the mouse over the "hover" link to see an example.
6. Scroll - When working with a long document, or viewing a long web page, you may need to scroll up or down. To scroll, use the mouse wheel, or click and drag the scroll bar.
7. Perform other functions - Many desktop mice also have buttons that can be programmed to perform any function. For example, many mice have two side buttons on the thumb portion of the mouse the button closest to the palm can be programmed to go back on web pages

Printer

Updated: 06/07/2019 by Computer Hope

A printer is an external hardware output device that takes the electronic data stored on a computer or other device and generates a hard copy of it. For example, if you created a report on your computer, you could print several copies to hand out at a staff meeting. Printers are one of the most popular computer peripherals and are commonly used to print text and photos. The picture is an example of an inkjet computer printer, the Lexmark Z605.

printers

Below is a list of all the different types of computer printers. Today, the most common printers used with a computer are inkjet and laser printers.

• 3D printer
• AIO (all-in-one) printer
• Dot matrix printer
• Inkjet printer
• Laser printer
• LED printer
• MFP (multifunction printer)
• Plotter
• Thermal printer

Printer interfaces

There are a few different ways a printer can connect to and communicate with a computer (referred to as interfaces). Today, the most common connection types are by USB cable or via Wi-Fi. Below is a full list of cables and interfaces used to connect a computer to a printer.

• Cat 5
• Firewire
• MPP-1150
• Parallel port
• SCSI
• Serial port
• USB
• Wi-Fi

What are the uses of a printer?

Each type of printer has different types of uses. Examples of more frequent uses of printers include the following.

3D printer

• Print tools or parts needed to build something.
• Print replacement parts for something that has broke.
• Print toys for children.

Inkjet printer

• Print copy of a document for school.
• Print pictures on photo printer.
• Print receipts for purchases made online.

Laser printer

• Quickly print hundreds of text documents or pages.
• Print hard copies of professional or legal documents.

History of various printers and how they work

Mechanical printer

The first mechanical printer was invented by Charles Babbage, for use with the Difference Engine, which Babbage developed in 1822. Babbage's printer utilized metal rods with printed characters on each rod to print text on rolls of paper that were fed through the device.

Dot matrix printer

The first dot matrix printer was created by IBM in 1957. However, the first dot matrix impact printer was introduced by Centronics in 1970. To create letters and images, the print head, which contains pins, sits over an ink ribbon. This ribbon rests above a piece of paper. As the print head moves across the ribbon (usually horizontally), the pins are pressed into the ribbon to imprint ink onto the page (similar to a typewriter). As these pins print a series of dots, you can see where this printer got its name. See our dot matrix printer page for further information and related links.

Inkjet printer

While inkjet printers started being developed in the late 1950s, it wasn't until the late 1970s that they were able to reproduce decent digital images. These higher quality inkjet printers were developed by multiple companies, including Canon, Epson, and Hewlett-Packard. Inkjet printers are similar to dot matrix printers in that the images they create are composed of dots. However, the dots on an inkjet printer are shot onto the page rather than using a ribbon and pins. Furthermore, an inkjet printer's dots are much smaller, and their print speed is faster. See our inkjet printer page for further information about this printer.

Laser printer

In the early 1970s, Gary Starkweather invented the laser printer while working at Xerox by modifying one of their model 7000 copiers. However, it wasn't until 1984 when Hewlett-Packard introduced the HP LaserJet that laser printers became more widely available and affordable. The following year, Apple introduced the Apple LaserWriter, which introduced PostScript technology to the printer market. Laser printers are a more complex than their predecessors. For information on how they work, see our laser printer definition.

3D printer

The 3D printer was created by Chuck Hull in 1984. 3D printers work by taking a digital blueprint of an object and reproducing it layer-by-layer using various materials such as plastic and metal alloys. See our 3D printer definition for further information about this printer.

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A scanner is a device that captures images from photographic prints, posters, magazine pages, and similar sources for computer editing and display. Scanners come in hand-held, feed-in, and flatbed types and for scanning black-and-white only, or color

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Scanner

 When referring to hardware, a scanner or optical scanner is a hardware input device that optically "reads" and image and converts it into a digital signal. For example, a scanner may be used to convert a printed picture, drawing, or document (hard copy) into a digital file which can be edited on a computer. The picture shows an example of a flatbed scanner, the Epson V300