3.2 COMPUTER HARDWARE

1. Introduction To Computer Hardware

Computer hardware refers to all the tangible components of the computer system. Every time, new devices are invented and used for different purposes.

Computer hardware equals the collection of physical elements that comprise a computer system. Computer hardware refers to the physical parts or components of a computer such as a monitor, keyboard, hard drive disk, mouse, printers, graphic cards, sound cards, memory, motherboard, chips, etc. all of which are physical object that you can actually touch.

2. INPUT DEVICES

UNIT INTRODUCTION

Input devices are used to enter data 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.

A. 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. Text input devices are all the devices that are used for entering text into the computer. There is a variety of devices that help us to input text into a computer.

Text input devices include:
 The Keyboard,

•  Voice Recognition Equipment
• OMR and Barcode readers
•  OCR and Optical readers
• MICR readers
• RFID readers
• Magnetic Strip Card Readers, etc

1. THE KEYBOARD

Definition: A keyboard is an input device, consisting of a set of keys used to
operate a computer. Each press of a key corresponds to a single written character of text, but to produce
some symbols requires pressing and holding several keys simultaneously. Usually, a standard keyboard has between 80 and 110 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 as pocket-sized computers. Christopher Latham Sholes was an American newspaper publisher. In 1866, he invented the first practical typewriter and the
QWERTY keyboard layout is still in use today.

ADVANTAGES OF KEYBOARD

• Keyboards are very common (commonly supplied with computers)
• Entering data and commands with the keyboard is faster than 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.

2. VOICE RECOGNITION EQUIPMENT

Voice Recognition Equipment (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.

ADVANTAGES

• 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

• The error rate is high, depending on the user’s accent.
• Words with the same pronunciations (Homophones) like see and sea cannot be distinguished
• Speech Recognition does can’t work in a 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 commas.

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.

4. BARCODE READERS

A bar code reader is an optical reader that uses laser beams to read bar codes that are printed on items
usually in supermarkets. 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.

5. 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.

6. MICR READERS

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 a MICR reader, which sends the check information to a computer for processing.

2.1. IMAGING DEVICES

Imaging input Devices are devices that input images such as still photos, motion pictures, graphics, video, etc. into the computer for processing. Common Imaging devices include:

• Image scanner
• Digital Camera
• Digital video (DV) camera
• Camcorder
• Webcam

1. 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:

• Flatbed scanner
• Pen or handheld scanner
• Sheet bed scanner
• Drum scanner.

2. WEBCAM

A Webcam 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 Webcams. 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.

3. DIGITAL CAMERA

A digital camera allows users to take pictures and store the photographed images digitally instead of storing them 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.

4. 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.

5. CAMCORDER

This is a lightweight easily portable video camera that records data in digital form onto a storage device such as a hard disk or a videotape.

2.2. AUDIO INPUT DEVICES

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. Examples of audio input devices include;

• Microphones,
• Tape players,
• CD/DVD players,
• MIDI devices
• Dictaphone, etc.

1. MICROPHONES

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. Various types of Microphones available. Microphones are connected to the sound card in the system unit.

2. MIDI DEVICES

MIDI (musical instrument digital interface) 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 e.g. you can set the beat speed, and add notes, to produce sound.

3. DICTAPHONE

This is 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.

2.3. GAMING INPUT DEVICES

Gaming input devices are devices specifically designed to be used for playing computer games.
Examples Include:

• Gaming Keyboard
• Joysticks and wheels
• Gamepad
• The light guns Dance pad
• Motion sensing game controllers

1. 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.

2. 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.

3. JOYSTICK

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. Joysticks can also be used as pointing devices.

4. GAMEPAD

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.

5. LIGHT GUNS

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.

6. 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.

7. 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, and play station move gadgets, among others.

2.4. 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. Common biometric devices include:

• Fingerprint scanner
• Face Recognition systems
• Hand geometry systems
• Signature verification systems
• Iris Recognition systems

1. FINGERPRINT SCANNER

A fingerprint scanner captures the 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.

2. 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.

3. 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.

4. 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. The signature verification system uses a specialized pen and tablet.

5. 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.

3. OUTPUT DEVICES

INTRODUCTION

Output is data that has been processed into a useful form called information. Computers generate several types of output, depending on the hardware and software being used and the requirements of the user.

An output device is any type of hardware component capable of conveying information to one or more people. Commonly used output devices include display devices, printers, Audio Output Devices, and others.

3.1. CATEGORIES OF COMPUTER OUTPUT

While working with a computer, a user encounters four basic categories of output:

• Text, (characters that are used to create words, sentences, and paragraphs)
• Graphics (non-text information such as drawings and charts),
• Audio(music, speech, or any other sound)
• Video (full-motion images played back at various speeds)

3.2. DISPLAY COMPUTERS

3.3. TERMS ASSOCIATED WITH PRINTERS

TERMS ASSOCIATED WITH PRINTERS

1. Toner is a powder used in laser printers and photocopiers to form printed text and images on paper.
2. DPI. (Dots per inch) is a measure of the number of individual dots printed in a line within the span of 1 inch (2.54 cm). The DPI value correlates with image resolution.
3. Hard copy is a permanent reproduction, in the form of a physical object, of any media suitable for direct use such as paper.
4. Page orientation is the way in which a rectangular page is focused for normal viewing. The two most common types of orientation are;

• portrait
• landscape.

A page in portrait orientation is taller than it is wide, with information printed across the shorter width of the paper. 

A page in landscape orientation is wider than it is tall, with information printed across the widest part of the paper.

3.4. AUDIO OUTPUT DEVICES

4. PROCESSING DEVICES

Processing devices are the computer electronic components and chips housed in the system unit. The system unit is a box-like case that houses the motherboard, the disks and drives bays, the power supply, and the cooling systems. The components in the system unit are connected to the motherboard. Two major components on the motherboard are the CPU and internal memory. A drive bay is a rectangular opening that typically holds disk drives.

THE MOTHERBOARD

The motherboard is a single circuit board that provides the path through which the processor communicates with internal and peripheral devices. The motherboard is also called the system board. The components attached to the motherboard include the processor chip, memory chips, buses, and Expansion Slots for Adapter Cards.

BUSES

The BUS is a common electrical path that enables data flow between the various system components. A bus allows the various devices inside and attached to the system unit to communicate with each other. All buses consist of
two parts:

• The data bus which transfers actual data bits and
• The address bus transfers information about where the data should go in memory.

EXPANSION SLOTS AND ADAPTER CARDS

An expansion slot is a socket on the motherboard that can hold an adapter card. An adapter card also called an expansion card, is a circuit board that increases the capabilities of the system or provides connections to peripherals. Some motherboards include all necessary capabilities and do not require adapter cards. Adapter cards are used for many supplemental capabilities, such as more memory, higher quality sound devices, a modem, extra ports, or graphics capabilities.