What is computer hardware?
Hardware is such parts of a computer that you can see, touch, and feel. Computer hardware is the collection of all the physical or tangible parts that make up a computer system. In another word, all the physical parts of the computer which can be touched or felt are known as hardware. The hardware consists of electronic and all devices used to perform various functions in the computer system. Some examples of hardware are keyboard, mouse, monitor, CPU, printer, scanner, ROM, RAM, etc.
Types of computer hardware
The hardware components of computers differ from one computer model to another according to their uses. However, the basic components and their functions are the same for all computer systems. Computer hardware can be categorized into four different types. They are:
- Input Unit(Hardware)
- Processing Unit(Hardware)
- Output Unit(Hardware)
- Memory and Storage Unit(Hardware)
1. Input Unit (Hardware)
The input unit consists of input devices. The devices that are used to enter data and instructions or commands into the computer are called input devices. The input devices can be considered as the eyes and ears of computers. With the help of input devices, we can enter data and give commands to the computer. Nowadays, various types of input devices are used in computers. Some of the commonly used input devices are described following.
The keyboard is an input device. It is a set of typewriter-like keys that enable the user to enter data into a computer. The keyboard consists of a set of alphabets (A-Z), digits (0,1,2,………9) symbols, and a functional and control key. When a key is pressed, an electrical signal is produced and it is detected by an electronic circuit called a keyboard encoder and converted to binary code. The keyboard is also called QWERTY because the first six keys on the top row of the keyboard contain the letter QWERTY.
A mouse is an input device that is most commonly used with a personal computer. It is used to point objects and give commands to the computer. When we move the mouse on the mouse pad, the mouse pointer on the screen moves in the corresponding direction. Items or icons can be moved or selected by pressing the mouse buttons (called clicking). There are two types of the mouse they are mechanical mouse and optical mouse.
A scanner is an input device that allows capturing drawing or photographing from hardcopy sources like paper, into electronic form. Using scanner drawings, graphs, photos, text can be converted to digital form by passing optical mechanisms.
A joystick is another input device that can be used for controlling the movement of the cursor or a pointer in a computer device. The pointer/cursor movement is controlled by the direction of a lever on the joystick. The input device of the joystick is mostly used for gaming applications and, sometimes in graphics applications.
A trackball is an input device that uses a ball that can rotate in any direction. It is also pointing devices like a mouse and the user spins the ball in different directions to move the cursor on the screen. An associated electronic circuit detects the direction and speed of the spin.
f. Light Pen
A light pen is an input device of a computer. It is based on light-sensitive and basically, a stylus (like pen), that is used to draw pictures, select the text and interact with user interface elements on a computer screen, or monitor. It is made of a photocell placed in a pen-shaped tube that detects the light emitted from the screen.
g. Touch Screen
A touch screen is a kind of screen that consists of a touch-sensitive display panel covering the screen. You can use your fingers or a stylus to select the objects on the screen and give commands to the computer. It replaces the use of a mouse or light pen as a pointing device. Touch screens are mostly used on portable computers such as laptop computers, palmtop computers, notebook computers, etc.
It is a touch-sensitive pad that is used as a pointing device. By putting your fingers on the touchpad, we can point the object on the screen and give the command to the computer. This pad is used in some portable computers such as laptop computers, palmtop computers, notebook computers, etc.
i. Web Camera
A web camera is a kind of camera that takes photos or videos and sends it from one computer to another computer when we will use it in Internet chatting and for video calling. It is used in messenger programs such as Facebook Messenger, Skype, IMO, Viber, WhatsApp, Snapchat, etc. It is connected to a computer often using a USB(Universal Serial Bus) port.
A Microphone is also an input device of the computer. It is also known as MIC that is used to input voice or sound into the computer. We can record speech, songs, etc. on the computer using a microphone. Computer stores recorded voice and sound in digital format. It is widely used in voice chatting over the Internet, video conferencing, and recording sound.
2. Processing Unit (Hardware)
The processing unit consists of processing devices. CPU(Central Processing Unit) is the main processing unit of the computer. It is the heart of the computer system. It is linked with various peripheral devices like input/out devices, storage devices, and so on. It performs all operations on data according to the program instructions. Processing Unite executes the program instructions and tells other parts of the computer what to do. The speed of the CPU is measured in terms of MegaHertz(MHz) or GigaHertz(GHz) or more. The CPU consists of three main parts. These are:
a. Control Unit(CU)
The Control Unit is also known as the brain of the computer. It directs all hardware components to operate and flow necessary signals to the components. It manages and coordinates the entire computer system. Control Unit receives the instructions from the program stored in the main memory, interprets the instructions, and directs other units or parts of the system to execute them. It is the central nervous system of other components of the computer system since it controls all other units in the system.
b. Arithmetic Logic Unit(ALU)
ALU (Arithmetic and Logical) is the place where the actual execution of instructions takes place during the processing of data. All data and instructions stored in primary memory before processing send to ALU for arithmetic or logical operation. ALU performs arithmetic calculations such as addition, subtraction, multiplication, division on integer, and real number. It can also perform a logical operation (AND, OR, NOT, IF) and comparison (such as greater than, less than, equal to, not equal to, etc) between two operands.
The CPU also consists of a number of registers and adder circuits. A register is a temporary storage device that holds data and instruction as long as it is being interpreted and executed. When the data and instructions are fetched from the main memory for processing these have to be stored in one of the registers of the CPU.
3. Output Unit(Hardware)
The output unit consists of output devices. The unit which is used to deliver data and information after processing it to the user in a human-understandable form is known as the output unit. The processed result of the computer is called output. The output of the computer can be presented in different ways such as softcopy and hard copy output. Some commonly used output devices are monitors, printers, speaker plotters, etc.
A monitor is the basic output device of a computer that is used to display any type of data and information from the computer. It is also called a Visual Display Unit and a softcopy-out device. Most monitors used in personal computers display the output in the text, graphics, and video. The monitor is a softcopy output device because it displays data and information temporarily until the electric power is supplied to it There are different types of monitor they are: CRT(Cathode Ray Tube) , LCD(Liquid Crystal Display), LED(Light Emitting Diode), etc.
A printer is the most popular output device of a computer that accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheets of paper. It is also known as a hardcopy output device. Printers provide information in a permanent readable form. The printer can be classified into two categories on the way how they print. They are impact printers and non-impact printers.
A speaker is the most commonly used sound output device. Speaker connects to a computer to generate sound. The special signal used to produce the sound that comes from a computer speaker is created by the computer’s sound card. Some speakers are also inbuilt inside the system unit and they produce different sounds while using the computer system. Various types of speakers are available in the market. The quality of the sound output depends on the speaker’s quality.
A plotter is the output device used to produce real and good quality graphics and drawing under computer controls. It uses ink pen or ink-jet to draw graphics or drawings. Either a single color or multicolor pen can be used. It is specially used in scientific and engineering fields.
4. Memory and Storage Unit(Hardware)
a) Magnetic Disk: Magnetic disk is widely used because it is relatively cheaper, high storage capacity, reliability and fast to access data in comparison with other storage technologies. Magnetic storage is read-write, which makes it possible to re-use the storage capacity over and over again by deleting older data. The storage capacity is also very large, making it attractive for storing very large amounts of data. Types of magnetic disk are hard disk, pen drive, floppy disk etc.
i) Hard Disk: Hard disk is a storage device used to store and provides relatively quick access to the large volume of data on electromagnetically charged surfaces. Hard disk is both input and output device since data can be both stored and retrieved from it. It is non-volatile in nature and is mainly used to store large volume of data permanently. It has read/write facility. Data in hard disk can be accessed randomly. The main components in hard disk are platters. Platters made up of aluminum coated with iron-oxide on both sides to stored data magnetically. A hard disk has a storage capacity in terms of gigabyte.
ii) Floppy Disk: Floppy disk is a removable disk so it can be used to transfer small amount of data from one computer to another. The disk is enclosed in a protective plastic cover called disk jacket to protect disk from external damage. Floppy disks are portable magnetic device. It is read/write memory. Data in floppy disk can be accessed randomly.
iii) Flash Memory: Flash memory is a memory storage device for computers and electronics. It is most often used in devices like digital cameras, USB flash drives, and video games. It is quite similar to EEPROM. Flash memory is one kind of Non-volatile random-access memory. It is slower than RAM but faster than hard drives. It is much used in small electronics because it is small and has no moving parts.
iv) Pen Drive: A pen drive, or a USB flash drive, is a portable data-storage device. Pen drives have replaced the floppy drives of old and have become the most popular data-storage devices among consumers. Micro, lightweight and handy, a pen drive can be easily carried and easily transfer data and files from one computer to another computer. Storage capacity of pen drive is MB to GB.
v) Memory Card: Memory card is a type of storage media that is often used to store photos, videos, or other data in electronic devices. Devices that commonly use a memory card include digital cameras, handheld computers, MP3 players, PDAs, cell phones etc. It is non-volatile memory. There are a handful of different types of memory cards on the market, each varying in size, compatibility, and storage capacity.
b) Optical Disk: Optical disk is an electronic data storage device that can be read and write. It is used for store music, movie and software. Optical disks are CD, DVD, Blue ray etc.
i) DVD: DVD stands for “Digital Versatile Disc“. The DVD can store any kind of digital data and is widely used for software and other computer files as well as video programs watched using DVD players. DVDs offer higher storage capacity than compact discs while having the same dimensions. It can store any type of data such as text, audio-video, graphics etc. Examples of DVD are DVD R, DVD ROM etc.
ii) Blue-Ray Disc: Blue-ray Disc (BD) is a digital optical disc data storage format. It was designed to replace the DVD format, in that it is capable of storing hours of video in high-definition (HDTV 720p and 1080p) and ultra high-definition resolution.