Computer hardware refers to the physical/tangible components or parts of the computer. Hardware is any physical part of the computer that you can touch, see and pickup.
Computer hardware is categorized in the following ways;
- Input hardware devices
- Processing devices
- Output devices
- Storage devices
- Communication/ Networking hardware
Input devices are used to enter data/instructions or commands in a form that the computer can use. They send the data or commands to the processing unit.
According to the type of data they input, they can be grouped into the following:
- Text input devices
- Pointing input Devices
- Imaging input Devices
- Gaming input Devices
- Audio input Devices
- Biometric input Devices and
- Other Specialized input devices
Text input devices
Text is a general word for all characters such as letters, numerical digits, symbols and marks that combine to form words, sentences, paragraphs and so on. There is a variety of devices that help us to input text into a computer. The following are the text input devices commonly used.
- The Keyboard
A keyboard is an input device, consisting of a set of keys (buttons) used to operate a computer. Each press of a key corresponds to a single written character of text, but to produce some symbols, it requires pressing and holding several keys simultaneously. Usually a standard keyboard has between 80 to110 keys. A keyboard is the main and most reliable computer input device.
The QWERTY is referred to as the “Universal” keyboard. The name “QWERTY” comes from the first six letters in the top alphabet row (the one just below the numbers). There are other setups also available such as Dvorak, ABCDE, GKOS, QWERTZ and AZERTY Keypads, Keyers and chorded keyboards have fewer keys, specially designed for devices such a pocket sized computers.
Advantages of Keyboard
- Keyboards are very common (commonly supplied with computers)
- Entering data and commands with keyboard is faster as compared to the mouse
- Keyboards are more reliable
Demerits of Keyboard
- It takes a lot of time to practice in order to type quickly
- Keys can easily become faulty due to dust.
- Some keyboards keys are very hard to press, causing fingers to hurt.
- Voice Recognition Equipment
Voice Recognition Equipment (a.k.a Speech recognition) converts spoken words to text. Computers with Speech recognition do not actually understand speech, but they are programmed to recognize a vocabulary of words, which can range from two words to millions of words.
- No typing of data is necessary.
- Voice recognition can be used by people whose hands are disabled.
- Dictating text is faster than typing.
- Voice Recognition systems are also ideal for the blind
Demerits of text input by speech Recognition
- Error rate is high, depending on user’s accent.
- Words with the same pronunciations (Homophones) like see and sea cannot be distinguished
- Speech Recognition does cannot work in noisy environment
- The Voice Recognition software must be trained to recognize more words.
- It requires the user to speak in a writing style,
i.e. even pronouncing the marks such as comma.
- Optical Mark Recognition (OMR)
Optical mark recognition (OMR) devices read hand-drawn marks such as small circles or rectangles. A person places these marks on a form, such as a test, survey, or questionnaire answer sheet.
The OMR device first reads a master document, such as an answer key sheet for a test, to record correct answers based on patterns of light; the remaining documents then are passed through the OMR device and their patterns of light are matched against the master document.
- Barcode readers/scanners
A bar code reader is an opticalreader that uses laser beams to read bar codes that are printed on items usually in super markets.
A bar code is an identification code that normally consists of a set of vertical lines and spaces of different widths. The bar code represents some data that identifies the item and the manufacturer.
- Optical Character Recognition (OCR)
Optical character recognition (OCR) is a technology that involves reading typewritten, computer-printed, or handwritten characters from ordinary documents and translating the images into a form that the computer can understand. OCR devices include a small optical scanner for reading characters and sophisticated software (OCR software) for analyzing what is read
- Magnetic Ink Character Readers (MICR)
Magnetic-ink character recognition (MICR) reader is used to read text printed with magnetized ink.
MICR readers are mainly used by the banking industry for processing checks. Each check is inserted into an MICR reader, which sends the check information to a computer for processing.
- Radio Frequency Identification (RFID) readers
Radio-frequency identification (RFID) is a technology that uses radio waves to transfer data from an electronic tag, attached to an object, through a reader for the purpose of identifying and tracking the object. RFID can work over a long distance. An RFID tag can be affixed to cars, computer equipment, books, mobile phones, etc.
- Magnetic Strip Card Readers
A magnetic stripe card reader reads the magnetic stripe on the back of credit cards, bank ATM cards, and other similar cards. Exposure to a magnet or magnetic field can erase the information and contents of a card’s magnetic stripe.
- Pointing Devices
A pointing device is an input device, which allows users to move a pointer and make selections on the computer screen. A pointing device is any piece of hardware that is used to input spatial data into a computer.
There are many examples of pointing devices such as:
- The Mouse
A mouse is an input pointing device that is used to select and icons and items on the screen. The mouse is a hand held device that lets you point to and make selections of items on your screen.
In a PC mouse there are mostly 2-3 buttons. A ball under the mouse senses movement. An optical mouse uses a light-emitting diode and photodiodes to detect movement relative to the underlying surface.
The Functions of a mouse
- The mouse is used as a pointer to move to, or select a particular section of the displayed window.
- It is used to complement the keyboard especially in a graphical interface environment
- Its right button provides an array of time saving shortcut menus.
There are two basic types of mice:
- Mechanical: Has a rubber or metal ball on its underside that can roll in all directions. Mechanical sensors within the mouse detect the direction the ball is rolling and move the screen pointer accordingly.
- Optical: Uses a laser (light to detect the mouse’s movement. but they are also more expensive. Mice connect to PCs in one of several ways: Serial mice connect directly to an RS-232C serial port or a PS/2 port. This is the simplest type of connection. PS/2 mice connect to a PS/2 port. USB mice connects to a USB (Universal Serial Bus) port
Advantages of using a mouse
- Moves cursor around the screen faster than using keystrokes
- A mouse is user-friendly for computer beginners.
- A mouse is easy and convenient to use with a graphical user interface.
Disadvantages of using a mouse include
- It is not easy and convenient to input text with a mouse.
- Issuing commands by using a mouse is slower than by using a keyboard.
- It needs some practice in order to control a mouse properly.
- A mouse is not accurate enough for drawings that require high precision.
- A mouse usually requires a flat surface to operate.
- A mouse needs more desk space to operate when compared with a trackball or a touchpad
- Requires moving hand from keyboard to mouse and back.
- Repeated motion can lead to carpal tunnel syndrome
Operations of a mouse/What can a mouse do?
- Clicking: It is an act of pressing and releasing the left hand button of the mouse once.
- Right clicking: It is an act of pressing and releasing the right mouse button once
- Double clicking: Is the act of pressing a computer mouse twice quickly without moving the mouse
- Dragging: Is an act of pointing at an item, then hold down the left mouse button as you move the mouse.
- Scrolling. It is an act of navigating the window page up or down by moving the wheel like button.
- Dropping. This refers to the release of the left button mouse after dragging an item.
- Cordless Mouse/Wireless mouse
The cordless mouse is a lot better than a normal mouse. It reduces the amount of work space needed to move the mouse around. This mouse runs on a battery. When you move the mouse it sends an infrared beam to a sensor which interprets it causing the pointer to move.
- Stylus pen & digitizing tablet
Stylus pen- The pen lets you draw on what is called a digitizing tablet that mirrors the surface area of the computer screen. The pen can be used as a standard mouse (without wires connected to it) or also as a free flowing drawing device. The pen is useful for drawing since drawing graphics with a mouse tends to be somewhat difficult.
The trackball is an upside-down mouse that remains stationary on your desk. It is the same principle as the mouse except that the rollers are reversed and the ball is on top. This ball does not need as much attention as the normal mouse because the only thing that touches it is your hand as the normal mouse touches a surface.
The touchpad has sensors that sense your touch. When they sense your touch they send a signal to the computer to move the mouse pointer to that location on the screen. Common on laptop computers.
- Light pen
Light pen- is a form of a light-sensitive wand used in conjunction with a computer’s CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy. A light pen can work with any CRT-based display, but not with LCD screens, projectors and other display devices.
- Touch Screens
A touch screen is a touch-sensitive input and display device. Users can interact with these devices by touching areas of the screen.
You touch words, pictures, numbers, letter, pointers or special locations identified on the screen. With some smart phones, portable media players, and other personal mobile devices, you can touch the screen to perform tasks such as dialing telephone numbers, entering text, and making on-screen selections.
Kiosks, which are freestanding computers, usually have touch screens. Many ATMs also have touch screens.
- Track Point
A Track Point, also called a pointing stick, is a cursor control device located in the middle of the keyboard between the G, H, and B keys. The control buttons are located in front of the keyboard toward the user. The Track Point is operated by pushing in the general direction the user wants the cursor to move. Increasing pressure causes faster movement.
- Imaging Devices
Imaging input Devices are devices that input images such as still photos, motion pictures, graphics, video etc. into the computer for processing.
- Image scanner
A scanner is a light-sensing input device that converts hardcopy documents, drawings, or pictures to an electronic version (softcopy), which can then be stored on a disk. The electronic version of scanned material is in the form of rows and columns of dots called a bitmap
Each dot on a bitmap consists of one or more bits of data.
Common types of scanners include:
- A flatbed scanner works like a copy machine except that it creates a file of the document rather than a paper copy.
- A sheet feed scanner has motorized rollers that can feed the source document across the scanning head during the scanning process.
- A handheld scanner can be manually passed over the image to be scanned.
- The quality of a scanner is determined by its resolution and color depth.
- Digital Camera
A digital camera allows users to take pictures and store the photographed images digitally instead of storing on a traditional film.
When you take pictures, the images are electronically stored in the camera. Later, you transfer a copy of the stored pictures to your computer or printer by connecting a cable between the digital camera and your computer.
What are the advantages of a digital camera over a traditional film camera?
- Ability to store images on media
- Ability to edit images
- Faster at taking images
- Images can be sent to other devices via a network
- Digital video (DV) camera
A digital video (DV) camera, by contrast records video as digital signals instead of analog signals. To transfer recorded images to the computer hard disk, users connect DV cameras directly to a port on the system unit. After saving the video on a storage medium, you can play it or edit it and burn it to a DVD using software programs on the computer.
This is a light weight video camera that records data in digital form onto a storage device such as a videotape.
- Web cam
A Web cam, also called a PC video camera, is a type of digital video camera that usually sits on top of the monitor. Some laptop computers have built-in Web cams.
Webcams enable users to:
- capture video and still images,
- send e-mail messages with video attachments,
- add live images to instant messages,
- broadcast live images over the Internet,
- and make video telephone calls
- Gaming input Devices
Gaming input devices are devices specifically designed to be used for playing computer games.
- Gaming keyboard
Gaming keyboards typically include programmable keys so that gamers can customize the keyboard to the game being played. The keys on gaming keyboards light up so that the keys are visible in all lighting conditions.
Some have small displays that show important game statistics, such as time to targets remaining.
- Gaming wheels
A gaming wheel is a steering wheel-type input device. Users turn the wheel to simulate driving a vehicle using programs on a computer. Most gaming wheels also include foot pedals for acceleration and braking actions. Gaming wheels include buttons, called triggers that you press to initiate certain events
Joystick- Consists of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer.
A gamepad controls the movement and actions of players or objects in video games or computer games. On the gamepad, users press buttons with their thumbs or move sticks in various directions to trigger events. Gamepads communicate with a game console or a personal computer via wired or wireless technology.
- Light gun
A light gun is used to shoot targets and moving objects after you pull the trigger on the weapon. Instead of emitting light, most light guns work by detecting light. When the user pulls the trigger, the screen uses one of several techniques to send light, which is received by a receptor in the barrel of the gun.
- Dance pad
A dance pad is a flat electronic device divided into panels that users press with their feet in response to instructions from a music video game. These games test the user’s ability to step on the correct panel at the correct time, following a pattern that is matching with the beat of a song.
- Motion sensing game controllers
These are devices that allow the user to guide onscreen elements by moving a handheld input device in predetermined directions through the air. Examples include the power glove, play station move gadgets, among others.
Audio input is the process of entering any sound into the computer such as speech, music, and sound effects. To enter sound into a computer, it must have a sound card. Audio input devices are plugged into a port on the sound card.
A sound card is a device that can be slotted into a computer to allow the use of audio components for multimedia applications. Without a sound card, Audio input and output is not possible.
A microphone is an instrument for converting sound waves into electrical energy variations, which may then input into the computer for processing, recording or audio playback. Microphones are connected to the sound card in the system unit.
- Musical Instrument Digital Interface (MIDI) devices
MIDI is the standard that defines how digital musical devices represent sound electronically. MIDI devices such as electronic pianos allow users to record and edit music. For example, you can set the beat speed, and add notes, to produce sound.
This the earliest device most commonly used to record speech for later playback or to be typed into print. It was established by Alexander Graham Bell in Washington, D.C. in 1881.
- Biometric input Devices
A biometric device translates a biological personal characteristic into a digital code that is stored or compared with a digital code stored in the computer.
- Fingerprint scanner
A fingerprint scanner captures curves and indentations of a fingerprint. Some grocery and retail stores now use fingerprint readers as a means of payment, where the customer’s fingerprint is linked to an account or credit card.
- Face Recognition systems
A face recognition system captures a live face image and compares it with a stored image to determine if the person is a legitimate user. Some buildings use face-recognition systems to secure access to rooms.
- Hand geometry system
Biometric devices measure the shape and size of a person’s hand using a hand geometry system. Some large companies use this system as time and attendance devices or as security devices. Day-care centers use this system to verify parents who pick up their children.
- Signature verification systems
A signature verification system recognizes the shape of your handwritten signature, as well as measures the pressure exerted and the motion used to write the signature. Signature verification system uses a specialized pen and tablet.
- Iris recognition system
These are devices that use iris recognition technology to read patterns in the iris of the eye. These patterns are as unique as a fingerprint. Iris recognition systems are used by government security organizations, the military and financial institutions that deal with highly sensitive data.
- Other Specialized input devices
There are many other special input devices that are used for doing special customized tasks.
- Remote Control
Remote control devices emit a beam of infrared light, which carries data signals. Remote control is commonly used with TVs but many laptop computers being produced come with remotes and a form of input device, which allow you to operate the laptop from a distance.
Chemical responses to the physical environment or movement can be converted to electrical signals by devices known as sensors, which input them it to the computer for processing. Various sensors can be used to measure heat, light, pressure, acidity, oxygen concentration, water flow, etc.