Computer Fundamenta

 

Computer Fundamentals

Computer is an electronic device i.e. used to work with information or compute. It is derived from the Latin word "computare" which means to calculate.

Our computer fundamentals include all topics of Computer fundamentals such as input devices, output devices, memory, CPU, motherboard, computer network, virus, software, hardware etc.

What is Computer?

A computer is a programmable electronic device that accepts raw data as input and processes it with a set of instructions (a program) to produce the result as output. It renders output just after performing mathematical and logical operations and can save the output for future use. It can process numerical as well as non-numerical calculations. The term "computer" is derived from the Latin word "computare" which means to calculate.

A computer is designed to execute applications and provides a variety of solutions through integrated hardware and software components. It works with the help of programs and represents the decimal numbers through a string of binary digits. It also has a memory that stores the data, programs, and result of processing. The components of a computer such as machinery that includes wires, transistors, circuits, hard disk are called hardware. Whereas, the programs and data are called software.

It is believed that the Analytical Engine was the first computer which was invented by Charles Babbage in 1837. It used punch cards as read-only memory. Charles Babbage is also known as the father of the computer.

The basic parts without which a computer cannot work are as follows:

• Processor: It executes instructions from software and hardware.
• Memory: It is the primary memory for data transfer between the CPU and storage.
• Motherboard: It is the part that connects all other parts or components of a computer.
• Storage Device: It permanently stores the data, e.g., hard drive.
• Input Device: It allows you to communicate with the computer or to input data, e.g., a keyboard.
• Output Device: It enables you to see the output, e.g., monitor.

 

 

 

Computers are divided into different types based on different criteria. Based on the size, a computer can be divided into five types:

1. Micro Computer
2. Mini Computer
3. Mainframe Computer
4. Super Computer
5. Workstations

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1. Micro Computer:

It is a single-user computer which has less speed and storage capacity than the other types. It uses a microprocessor as a CPU. The first microcomputer was built with 8-bit microprocessor chips. The common examples of microcomputers include laptops, desktop computers, personal digital assistant (PDA), tablets, and smartphones. Microcomputers are generally designed and developed for general usage like browsing, searching for information, internet, MS Office, social media, etc.

2. Mini Computer:

Mini-computers are also known as "Midrange Computers." They are not designed for a single. They are multi-user computers designed to support multiple users simultaneously. So, they are generally used by small businesses and firms. Individual departments of a company use these computers for specific purposes. For example, the admission department of a University can use a Mini-computer for monitoring the admission process.

3. Mainframe Computer:

It is also a multi-user computer capable of supporting thousands of users simultaneously. They are used by large firms and government organizations to run their business operations as they can store and process large amounts of data. For example, Banks, universities, and insurance companies use mainframe computers to store the data of their customers, students, and policyholders, respectively.

4. Super Computer:

Super-computers are the fastest and most expensive computers among all types of computers. They have huge storage capacities and computing speeds and thus can perform millions of instructions per second. The super-computers are task-specific and thus used for specialized applications such as large-scale numerical problems in scientific and engineering disciplines including applications in electronics, petroleum engineering, weather forecasting, medicine, space research and more. For example, NASA uses supercomputers for launching space satellites and monitoring and controlling them for space exploration.

5. Work stations:

It is a single-user computer. Although it is like a personal computer, it has a more powerful microprocessor and a higher-quality monitor than a microcomputer. In terms of storage capacity and speed, it comes between a personal computer and minicomputer. Work stations are generally used for specialized applications such as desktop publishing, software development, and engineering designs.

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Benefits of Using a Computer:

• Increases your productivity: A computer increases your productivity. For example, after having a basic understanding of a word processor, you can create, edit, store, and print the documents easily and quickly.
• Connects to the Internet: It connects you to the internet that allows you to send emails, browse content, gain information, use social media platforms, and more. By connecting to the internet, you can also connect to your long-distance friends and family members.
• Storage: A computer allows you to store a large amount of information, e.g., you can store your projects, ebooks, documents, movies, pictures, songs, and more.
• Organized Data and Information: It not only allows you to store data but also enables you to organize your data. For example, you can create different folders to store different data and information and thus can search for information easily and quickly.
• Improves your abilities: It helps write good English if you are not good at spelling and grammar. Similarly, if you are not good at math, and don't have a great memory, you can use a computer to perform calculations and store the results.
• Assist the physically challenged: It can be used to help the physically challenged, e.g., Stephen Hawking, who was not able to speak used computer to speak. It also can be used to help blind people by installing special software to read what is on the screen.
• Keeps you entertained: You can use the computer to listen to songs, watch movies, play games and more.

 

The computer has become a part of our life. There are plenty of things that we do in a day are dependent on a computer. Some of the common examples are as follows:

1. ATM: While withdrawing cash from an ATM, you are using a computer that enables the ATM to take instructions and dispense cash accordingly.
2. Digital currency: A computer keeps a record of your transactions and balance in your account and the money deposited in your account in a bank is stored as a digital record or digital currency.
3. Trading: Stock markets use computers for day to day trading. There are many advanced algorithms based on computers that handle trading without involving humans.
4. Smartphone: The smartphone that we use throughout the day for calling, texting, browsing is itself a computer.
5. VoIP: All voice over IP communication (VoIP) is handled and done by computers.

History of Computers

The first counting device was used by the primitive people. They used sticks, stones and bones as counting tools. As human mind and technology improved with time more computing devices were developed. Some of the popular computing devices starting with the first to recent ones are described below;

 

Abacus

 

The history of computer begins with the birth of abacus which is believed to be the first computer. It is said that Chinese invented Abacus around 4,000 years ago.

It was a wooden rack which has metal rods with beads mounted on them. The beads were moved by the abacus operator according to some rules to perform arithmetic calculations. Abacus is still used in some countries like China, Russia and Japan. An image of this tool is shown below;

 

Napier's Bones

It was a manually-operated calculating device which was invented by John Napier (1550-1617) of Merchiston. In this calculating tool, he used 9 different ivory strips or bones marked with numbers to multiply and divide. So, the tool became known as "Napier's Bones. It was also the first machine to use the decimal point.

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Pascaline

Pascaline is also known as Arithmetic Machine or Adding Machine. It was invented between 1642 and 1644 by a French mathematician-philosopher Biaise Pascal. It is believed that it was the first mechanical and automatic calculator.

Pascal invented this machine to help his father, a tax accountant. It could only perform addition and subtraction. It was a wooden box with a series of gears and wheels. When a wheel is rotated one revolution, it rotates the neighboring wheel. A series of windows is given on the top of the wheels to read the totals. An image of this tool is shown below;

Stepped Reckoner or Leibnitz wheel

It was developed by a German mathematician-philosopher Gottfried Wilhelm Leibnitz in 1673. He improved Pascal's invention to develop this machine. It was a digital mechanical calculator which was called the stepped reckoner as instead of gears it was made of fluted drums. See the following image;

Difference Engine

In the early 1820s, it was designed by Charles Babbage who is known as "Father of Modern Computer". It was a mechanical computer which could perform simple calculations. It was a steam driven calculating machine designed to solve tables of numbers like logarithm tables.

Analytical Engine

This calculating machine was also developed by Charles Babbage in 1830. It was a mechanical computer that used punch-cards as input. It was capable of solving any mathematical problem and storing information as a permanent memory.

Tabulating Machine

It was invented in 1890, by Herman Hollerith, an American statistician. It was a mechanical tabulator based on punch cards. It could tabulate statistics and record or sort data or information. This machine was used in the 1890 U.S. Census. Hollerith also started the Hollerith?s Tabulating Machine Company which later became International Business Machine (IBM) in 1924.

Differential Analyzer

It was the first electronic computer introduced in the United States in 1930. It was an analog device invented by Vannevar Bush. This machine has vacuum tubes to switch electrical signals to perform calculations. It could do 25 calculations in few minutes.

Mark I

The next major changes in the history of computer began in 1937 when Howard Aiken planned to develop a machine that could perform calculations involving large numbers. In 1944, Mark I computer was built as a partnership between IBM and Harvard. It was the first programmable digital computer.

Generations of Computers

A generation of computers refers to the specific improvements in computer technology with time. In 1946, electronic pathways called circuits were developed to perform the counting. It replaced the gears and other mechanical parts used for counting in previous computing machines.

In each new generation, the circuits became smaller and more advanced than the previous generation circuits. The miniaturization helped increase the speed, memory and power of computers. There are five generations of computers which are described below;

First Generation Computers

The first generation (1946-1959) computers were slow, huge and expensive. In these computers, vacuum tubes were used as the basic components of CPU and memory. These computers were mainly depended on batch operating system and punch cards. Magnetic tape and paper tape were used as output and input devices in this generation;

Some of the popular first generation computers are;

• ENIAC ( Electronic Numerical Integrator and Computer)
• EDVAC ( Electronic Discrete Variable Automatic Computer)
• UNIVACI( Universal Automatic Computer)
• IBM-701
• IBM-650

Second Generation Computers

The second generation (1959-1965) was the era of the transistor computers. These computers used transistors which were cheap, compact and consuming less power; it made transistor computers faster than the first generation computers.

In this generation, magnetic cores were used as the primary memory and magnetic disc and tapes were used as the secondary storage. Assembly language and programming languages like COBOL and FORTRAN, and Batch processing and multiprogramming operating systems were used in these computers.

Some of the popular second generation computers are;

• IBM 1620
• IBM 7094
• CDC 1604
• CDC 3600
• UNIVAC 1108

Third Generation Computers

The third generation computers used integrated circuits (ICs) instead of transistors. A single IC can pack huge number of transistors which increased the power of a computer and reduced the cost. The computers also became more reliable, efficient and smaller in size. These generation computers used remote processing, time-sharing, multi programming as operating system. Also, the high-level programming languages like FORTRON-II TO IV, COBOL, PASCAL PL/1, ALGOL-68 were used in this generation.

Some of the popular third generation computers are;

• IBM-360 series
• Honeywell-6000 series
• PDP(Personal Data Processor)
• IBM-370/168
• TDC-316

Fourth Generation Computers

The fourth generation (1971-1980) computers used very large scale integrated (VLSI) circuits; a chip containing millions of transistors and other circuit elements. These chips made this generation computers more compact, powerful, fast and affordable. These generation computers used real time, time sharing and distributed operating system. The programming languages like C, C++, DBASE were also used in this generation.

Some of the popular fourth generation computers are;

• DEC 10
• STAR 1000
• PDP 11
• CRAY-1(Super Computer)
• CRAY-X-MP(Super Computer)

Fifth Generation Computers

In fifth generation (1980-till date) computers, the VLSI technology was replaced with ULSI (Ultra Large Scale Integration). It made possible the production of microprocessor chips with ten million electronic components. This generation computers used parallel processing hardware and AI (Artificial Intelligence) software. The programming languages used in this generation were C, C++, Java, .Net, etc.

Some of the popular fifth generation computers are;

• Desktop
• Laptop
• NoteBook
• UltraBook
• ChromeBook

Types of Computer

We can categorize computer in two ways: on the basis of data handling capabilities and size.

On the basis of data handling capabilities, the computer is of three types:

• Analogue Computer
• Digital Computer
• Hybrid Computer

1) Analogue Computer

Analogue computers are designed to process analogue data. Analogue data is continuous data that changes continuously and cannot have discrete values. We can say that analogue computers are used where we don't need exact values always such as speed, temperature, pressure and current.

Analogue computers directly accept the data from the measuring device without first converting it into numbers and codes. They measure the continuous changes in physical quantity and generally render output as a reading on a dial or scale. Speedometer and mercury thermometer are examples of analogue computers.

Advantages of using analogue computers:

• It allows real-time operations and computation at the same time and continuous representation of all data within the rage of the analogue machine.
• In some applications, it allows performing calculations without taking the help of transducers for converting the inputs or outputs to digital electronic form and vice versa.
• The programmer can scale the problem for the dynamic range of the analogue computer. It provides insight into the problem and helps understand the errors and their effects.

Types of analogue computers:

• Slide Rules: It is one of the simplest types of mechanical analogue computers. It was developed to perform basic mathematical calculations. It is made of two rods. To perform the calculation, the hashed rod is slid to line up with the markings on another rod.
• Differential Analysers: It was developed to perform differential calculations. It performs integration using wheel-and-disc mechanisms to solve differential calculations.
• Castle Clock: It was invented by Al-Jarazi. It was able to save programming instructions. Its height was around 11 feet and it was provided with the display of time, the zodiac, and the solar and lunar orbits. This device also could allow users to set the length of the day as per the current season.
• Electronic Analogue Computer: In this type of analogue computer, electrical signals flow through capacitors and resistors to simulate physical phenomena. Here, the mechanical interaction of components does not take place. The voltage of the electrical signal generates the appropriate displays.

2) Digital Computer

Digital computer is designed to perform calculations and logical operations at high speed. It accepts the raw data as input in the form of digits or binary numbers (0 and 1) and processes it with programs stored in its memory to produce the output. All modern computers like laptops, desktops including smartphones that we use at home or office are digital computers.

Advantages of digital computers:

• It allows you to store a large amount of information and to retrieve it easily whenever you need it.
• You can easily add new features to digital systems more easily.
• Different applications can be used in digital systems just by changing the program without making any changes in hardware
• The cost of hardware is less due to the advancement in the IC technology.
• It offers high speed as the data is processed digitally.
• It is highly reliable as it uses error correction codes.
• Reproducibility of results is higher as the output is not affected by noise, temperature, humidity, and other properties of its components.

3) Hybrid Computer

Hybrid computer has features of both analogue and digital computer. It is fast like an analogue computer and has memory and accuracy like digital computers. It can process both continuous and discrete data. It accepts analogue signals and convert them into digital form before processing. So, it is widely used in specialized applications where both analogue and digital data is processed. For example, a processor is used in petrol pumps that converts the measurements of fuel flow into quantity and price. Similarly, they are used in airplanes, hospitals, and scientific applications.

Advantages of using hybrid computers:

• Its computing speed is very high due to the all-parallel configuration of the analogue subsystem.
• It produces precise and quick results that are more accurate and useful.
• It has the ability to solve and manage big equation in real-time.
• It helps in the on-line data processing.

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On the basis of size, the computer can be of five types:

1) Supercomputer

Supercomputers are the biggest and fastest computers. They are designed to process huge amount of data. A supercomputer can process trillions of instructions in a second. It has thousands of interconnected processors.

Supercomputers are particularly used in scientific and engineering applications such as weather forecasting, scientific simulations and nuclear energy research. The first supercomputer was developed by Roger Cray in 1976.

Characteristics or applications of supercomputers:

• It has the ability to decrypt your password to enhance protection for security reasons.
• It produces excellent results in animations.
• It is used for virtual testing of nuclear weapons and critical medical tests.
• It can study and understand climate patterns and forecast weather conditions. It can run in NOAA's system (National Oceanic and Atmospheric Administration) that can execute any type of simple and logical data.
• It helps in designing the flight simulators for pilots at the beginner level for their training.
• It helps in extracting useful information from data storage centres or cloud system. For example, in insurance companies.
• It has played a vital role in managing the online currency world such as stock market and bitcoin.
• It helps in the diagnosis of various critical diseases and in producing accurate results in brain injuries, strokes, etc.
• It helps in scientific research areas by accurately analysing data obtained from exploring the solar system, satellites, and movement of Earth.
• It also used in a smog control system where it predicts the level of fog and other pollutants in the atmosphere.

2) Mainframe computer

Mainframe computers are designed to support hundreds or thousands of users simultaneously. They can support multiple programs at the same time. It means they can execute different processes simultaneously. These features of mainframe computers make them ideal for big organizations like banking and telecom sectors, which need to manage and process high volume of data.

Mainframe computers are designed to support hundreds or thousands of users simultaneously. They can support multiple programs at the same time. It means they can execute different processes simultaneously. These features of mainframe computers make them ideal for big organizations like banking and telecom sectors, which need to manage and process a high volume of data that requires integer operations such as indexing, comparisons, etc.

Characteristics of Mainframe Computers:

• It can process huge amount of data, e.g. millions of transactions in a second in the banking sector.
• It has a very long life. It can run smoothly for up to 50 years after proper installation.
• It gives excellent performance with large scale memory management.
• It has the ability to share or distribute its workload among other processors and input/output terminals.
• There are fewer chances of error or bugs during processing in mainframe computers. If any error occurs it can fix it quickly without affecting the performance.
• It has the ability to protect the stored data and other ongoing exchange of information and data.

Applications of mainframe computers:

• In health care, it enabled hospitals to maintain a record of their millions of patients in order to contact them for treatment or related to their appointment, medicine updates or disease updates.
• In the field of defence, it allows the defence departments to share a large amount of sensitive information with other branches of defence.
• In the field of education, it helps big universities to store, manage and retrieve data related to their courses, admissions, students, teachers, employees and affiliated schools and colleges.
• In the retail sector, the retail companies that have a huge customer base and branches use mainframe computers to handle and execute information related to their inventory management, customer management, and huge transactions in a short duration.

3) Miniframe or Minicomputer

It is a midsize multiprocessing computer. It consists of two or more processors and can support 4 to 200 users at one time. Miniframe computers are used in institutes and departments for tasks such as billing, accounting and inventory management. A minicomputer lies between the mainframe and microcomputer as it is smaller than mainframe but larger than a microcomputer.

Characteristics of miniframe or minicomputer:

• It is light weight that makes it easy to carry and fit anywhere.
• It is less expensive than mainframe computers.
• It is very fast compared to its size.
• It remains charged for a long time.
• It does not require a controlled operational environment.

Applications of minicomputers:

A minicomputer is mainly used to perform three primary functions, which are as follows:

• Process control: It was used for process control in manufacturing. It mainly performs two primary functions that are collecting data and feedback. If any abnormality occurs in the process, it is detected by the minicomputer and necessary adjustments are made accordingly.
• Data management: It is an excellent device for small organizations to collect, store and share data. Local hospitals and hotels can use it to maintain the records of their patients and customers respectively.
• Communications Portal: It can also play the role of a communication device in larger systems by serving as a portal between a human operator and a central processor or computer.

4) Workstation

Workstation is a single user computer that is designed for technical or scientific applications. It has a faster microprocessor, a large amount of RAM and high speed graphic adapters. It generally performs a specific job with great expertise; accordingly, they are of different types such as graphics workstation, music workstation and engineering design workstation.

Characteristics of workstation computer:

• It is a high-performance computer system designed for a single user for business or professional use.
• It has larger storage capacity, better graphics, and more powerful CPU than a personal computer.
• It can handle animation, data analysis, CAD, audio and video creation and editing.

Any computer that has the following five features, can be termed as a workstation or can be used as a workstation.

• Multiple Processor Cores: It has more processor cores than simple laptops or computers.
• ECC RAM: It is provided with Error-correcting code memory that can fix memory errors before they affect the system's performance.
• RAID (Redundant Array of Independent Disks): It refers to multiple internal hard drives to store or process data. RAID can be of different types, for example, there can be multiple drives to process data or mirrored drives where if one drive does not work than other starts functioning.
• SSD: It is better than conventional hard-disk drives. It does not have moving parts, so the chances of physical failure are very less.
• Optimized, Higher end GPU: It reduces the load on CPU. E.g., CPU has to do less work while processing the screen output.

5) Microcomputer

Microcomputer is also known as a personal computer. It is a general-purpose computer that is designed for individual use. It has a microprocessor as a central processing unit, memory, storage area, input unit and output unit. Laptops and desktop computers are examples of microcomputers. They are suitable for personal work that may be making an assignment, watching a movie, or at office for office work.

Characteristics of a microcomputer:

• It is the smallest in size among all types of computers.
• A limited number of software can be used.
• It is designed for personal work and applications. Only one user can work at a time.
• It is less expansive and easy to use.
• It does not require the user to have special skills or training to use it.
• Generally, comes with single semiconductor chip.
• It is capable of multitasking such as printing, scanning, browsing, watching videos, etc.

Computer Components

There are 5 main computer components that are given below:

• Input Devices
• CPU
• Output Devices
• Primary Memory
• Secondary Memory

The operations of computer components are given below:

1) Inputting: It is the process of entering raw data, instructions and information into the computer. It is performed with the help of input devices.

2) Storing: The computer has primary memory and secondary storage to store data and instructions. It stores the data before sending it to CPU for processing and also stores the processed data before displaying it as output.

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3) Processing: It is the process of converting the raw data into useful information. This process is performed by the CPU of the computer. It takes the raw data from storage, processes it and then sends back the processed data to storage.

4) Outputting: It is the process of presenting the processed data through output devices like monitor, printer and speakers.

5) Controlling: This operation is performed by the control unit that is part of CPU. The control unit ensures that all basic operations are executed in a right manner and sequence.

Input Devices

Input device enables the user to send data, information, or control signals to a computer. The Central Processing Unit (CPU) of a computer receives the input and processes it to produce the output.

Some of the popular input devices are:

1. Keyboard
2. Mouse
3. Scanner
4. Joystick
5. Light Pen
6. Digitizer
7. Microphone
8. Magnetic Ink Character Recognition (MICR)
9. Optical Character Reader (OCR)
10. Digital Camera
11. Paddle
12. Steering Wheel
13. Gesture recognition devices
14. Light Gun
15. Touch Pad
16. Remote
17. Touch screen
18. VR
19. Webcam
20. Biometric Devices

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1) Keyboard

The keyboard is a basic input device that is used to enter data into a computer or any other electronic device by pressing keys. It has different sets of keys for letters, numbers, characters, and functions. Keyboards are connected to a computer through USB or a Bluetooth device for wireless communication.

Types of keyboards: There can be different types of keyboards based on the region and language used. Some of the common types of keyboards are as follows:

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i) QWERTY Keyboard:

It is the most commonly used keyboard with computers in modern times. It is named after the first six letters of the top row of buttons and is even popular in countries that do not use Latin-based alphabet. It is so popular that some people think that it is the only type of keyboard to use with computers as an input device.

ii) AZERTY Keyboard:

It is considered the standard French keyboard. It is developed in France as an alternative layout to the QWERTY layout and is mainly used in France and other European countries. Some countries have manufactured their own versions of AZERTY.

Its name is derived from the first six letters that appear on the top left row of the keyboard. The Q and W keys in AZERTY keyboard are interchanged with A and Z keys in QWERTY keyboard. Furthermore, in AZERTY keyboard M key is located to the left of the L key.

AZERTY keyboard differs from QWERTY keyboard not only in the placement of letters but also in many other ways, e.g., it gives emphasis on accents, which is required for writing European languages like French.

iii) DVORAK Keyboard:

This type of keyboard layout was developed to increase the typing speed by reducing the finger movement while typing. The most frequently used letters are kept in a home row to improve typing.

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2) Mouse

The mouse is a hand-held input device which is used to move cursor or pointer across the screen. It is designed to be used on a flat surface and generally has left and right button and a scroll wheel between them. Laptop computers come with a touchpad that works as a mouse. It lets you control the movement of cursor or pointer by moving your finger over the touchpad. Some mouse comes with integrated features such as extra buttons to perform different buttons.

The mouse was invented by Douglas C. Engelbart in 1963. Early mouse had a roller ball integrated as a movement sensor underneath the device. Modern mouse devices come with optical technology that controls cursor movements by a visible or invisible light beam. A mouse is connected to a computer through different ports depending on the type of computer and type of a mouse.

Common types of the mouse:

i) Trackball Mouse:

It is a stationary input device that has ball mechanism to move the pointer or cursor on the screen. The ball is half inserted in the device and can be easily rolled with finger, thumb or the palm to move the pointer on the screen. The device has sensor to detect the rotation of ball. It remains stationary; you don't need to move it on the operating surface. So, it is an ideal device if you have limited desk space as you don't need to move it like a mouse.

ii) Mechanical Mouse:

It has a system of a ball and several rollers to track its movement. It is a corded type of mouse. A mechanical mouse can be used for high performance. The drawback is that they tend to get dust into the mechanics and thus require regular cleaning.

iii) Optical Mouse:

An optical mouse uses optical electronics to track its movement. It is more reliable than a mechanical mouse and also requires less maintenance. However, its performance is affected by the surface on which it is operated. Plain non-glossy mouse mat should be used for best results. The rough surface may cause problems for the optical recognition system, and the glossy surface may reflect the light wrongly and thus may cause tracking issues.

iv) Cordless or Wireless Mouse:

As the name suggests, this type of mouse lacks cable and uses wireless technology such as IrDA (infrared) or radio (Bluetooth or Wi-Fi) to control the movement of the cursor. It is used to improve the experience of using a mouse. It uses batteries for its power supply.

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3) Scanner

The scanner uses the pictures and pages of text as input. It scans the picture or a document. The scanned picture or document then converted into a digital format or file and is displayed on the screen as an output. It uses optical character recognition techniques to convert images into digital ones. Some of the common types of scanners are as follows:

Types of Scanner:

i) Flatbed Scanner:

It has a glass pane and a moving optical CIS or CCD array. The light illuminates the pane, and then the image is placed on the glass pane. The light moves across the glass pane and scans the document and thus produces its digital copy. You will need a transparency adapter while scanning transparent slides.

ii) Handheld Scanner:

It is a small manual scanning device which is held by hand and is rolled over a flat image that is to be scanned. The drawback in using this device is that the hand should be steady while scanning; otherwise, it may distort the image. One of the commonly used handheld scanners is the barcode scanner which you would have seen in shopping stores.

iii) Sheetfed Scanner:

In this scanner, the document is inserted into the slot provided in the scanner. The main components of this scanner include the sheet-feeder, scanning module, and calibration sheet. The light does not move in this scanner. Instead, the document moves through the scanner. It is suitable for scanning single page documents, not for thick objects like books, magazines, etc.

iv) Drum Scanner:

Drum scanner has a photomultiplier tube (PMT) to scan images. It does not have a charge-coupled device like a flatbed scanner. The photomultiplier tube is extremely sensitive to light. The image is placed on a glass tube, and the light moves across the image, which produces a reflection of the image which is captured by the PMT and processed. These scanners have high resolution and are suitable for detailed scans.

v) Photo Scanner:

It is designed to scan photographs. It has high resolution and color depth, which are required for scanning photographs. Some photo scanners come with in-built software for cleaning and restoring old photographs.

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4) Joystick

A joystick is also a pointing input device like a mouse. It is made up of a stick with a spherical base. The base is fitted in a socket that allows free movement of the stick. The movement of stick controls the cursor or pointer on the screen.

The frist joystick was invented by C. B. Mirick at the U.S. Naval Research Laboratory. A joystick can be of different types such as displacement joysticks, finger-operated joysticks, hand operated, isometric joystick, and more. In joystick, the cursor keeps moving in the direction of the joystick unless it is upright, whereas, in mouse, the cursor moves only when the mouse moves.

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5) Light Pen

A light pen is a computer input device that looks like a pen. The tip of the light pen contains a light-sensitive detector that enables the user to point to or select objects on the display screen. Its light sensitive tip detects the object location and sends the corresponding signals to the CPU. It is not compatible with LCD screens, so it is not in use today. It also helps you draw on the screen if needed. The first light pen was invented around 1955 as a part of the Whirlwind project at the Massachusetts Institute of Technology (MIT).

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6) Digitizer

Digitizer is a computer input device that has a flat surface and usually comes with a stylus. It enables the user to draw images and graphics using the stylus as we draw on paper with a pencil. The images or graphics drawn on the digitizer appear on the computer monitor or display screen. The software converts the touch inputs into lines and can also convert handwritten text to typewritten words.

It can be used to capture handwritten signatures and data or images from taped papers. Furthermore, it is also used to receive information in the form of drawings and send output to a CAD (Computer-aided design) application and software like AutoCAD. Thus, it allows you to convert hand-drawn images into a format suitable for computer processing.

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7) Microphone

The microphone is a computer input device that is used to input the sound. It receives the sound vibrations and converts them into audio signals or sends to a recording medium. The audio signals are converted into digital data and stored in the computer. The microphone also enables the user to telecommunicate with others. It is also used to add sound to presentations and with webcams for video conferencing. A microphone can capture audio waves in different ways; accordingly the three most common types are described below:

i) Dynamic:

It is the most commonly used microphone with a simple design. It has a magnet which is wrapped by a metal coil and a thin sheet on the front end of the magnet. The sheet transfers vibrations from sound waves to the coil and from coil to electric wires which transmit the sound like an electrical signal.

ii) Condenser:

It is designed for audio recording and has a very sensitive and flat frequency response. It has a front plate called diaphragm and a back plate parallel to the front plate. When sound hits the diaphragm, it vibrates the diaphragm and alters the distance between the two plates. The changes in distance are transmitted as electric signals.

iii) Ribbon:

It is known for its reliability. It has a thin ribbon made of aluminum, duraluminum, or nanofilm suspended in a magnetic field. The sound waves cause vibrations in the ribbon, which generate a voltage proportional to the velocity of the vibration. The voltage is transmitted as an electrical signal. Early ribbon microphones had a transformer to increase the output voltage, but modern ribbon microphones come with advanced magnets to produce a strong signal.

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8) Magnetic Ink Character Recognition (MICR)

MICR computer input device is designed to read the text printed with magnetic ink. MICR is a character recognition technology that makes use of special magnetized ink which is sensitive to magnetic fields. It is widely used in banks to process the cheques and other organizations where security is a major concern. It can process three hundred cheques in a minute with hundred-percent accuracy. The details on the bottom of the cheque (MICR No.) are written with magnetic ink. A laser printer with MICR toner can be used to print the magnetic ink.

The device reads the details and sends to a computer for processing. A document printed in magnetic ink is required to pass through a machine which magnetizes the ink, and the magnetic information is then translated into characters.

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9) Optical Character Reader (OCR)

OCR computer input device is designed to convert the scanned images of handwritten, typed or printed text into digital text. It is widely used in offices and libraries to convert documents and books into electronic files.

It processes and copies the physical form of a document using a scanner. After copying the documents, the OCR software converts the documents into a two-color (black and white), version called bitmap. Then it is analyzed for light and dark areas, where the dark areas are selected as characters, and the light area is identified as background. It is widely used to convert hard copy legal or historic documents into PDFs. The converted documents can be edited if required like we edit documents created in ms word.

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10) Digital camera:

It is a digital device as it captures images and records videos digitally and then stores them on a memory card. It is provided with an image sensor chip to capture images, as opposed to film used by traditional cameras. Besides this, a camera that is connected to your computer can also be called a digital camera.

It has photosensors to record light that enters the camera through the lens. When the light strikes the photosensors, each of the sensors returns the electrical current, which is used to create the images.

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11) Paddle:

It is a simple input device that is widely used in games. It is a wheel that is held by hand and looks like a volume knob on a stereo that is used to increase or decrease the volume. Paddle moves or controls cursor or any other objects in the game in a back-and-forth motion. It is widely used as an alternative to the joystick. Besides this, the term paddle also refers to many handheld devices designed to control a function in an electronic device, computer, etc.

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12) Steering wheel:

It is used as an input device in racing video games such as car racing games or in driving programs as virtual simulators to steer a vehicle. It works like the real steering wheel by allowing you to take a right or left turn. A steering wheel may be provided with acceleration and brake pedal devices and a mechanism for shifting gears. Thus, it makes racing games more adventurous and entertaining.

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13) Gesture recognition devices:

These devices take human gestures as input. There are many such devices that respond to gestures. For example, Kinect is one such device that observes the movement of a player's body and interprets these movements as inputs to video games. This feature is also available in certain tablets and smartphones where you can perform certain tasks such as taking pictures using finger gestures such as swiping, pinching, etc.

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14) Light Gun:

As the name suggests, it is a pointing input device that is designed to point at and shoot the targets on the screen in a video game, or arcade, etc. The light gun was used for the first time on the MIT Whirwind computer. When the gun is pointed at the target on the screen and the trigger is pulled, the screen goes blank for a fraction of a second. During this moment, the photodiode, which is present in the barrel, determines where the gun is pointed. For example, shooting ducks in a duck hunt game.

15) Touchpad:

It is usually found in laptops as a substitute for the mouse. It allows you to move or control the cursor on the screen using your finger. Just like a mouse, it also has two buttons for right and left click. Using the touchpad, you can perform all the tasks that you do with a mouse, such as selecting an object on the screen, copy, paste, delete, open a file or folder, and more.

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16) Remote:

It is a hardware device designed to control the functioning of a device, e.g., a TV remote that can be used to change channels, increase or decrease the volume, from a distance without leaving the seat. The first cordless TV remote was invented by Dr. Robert Adler of Zenith in 1956. The remote sends the electromagnetic waves to communicate with the device. These waves can be infrared rays, radio waves, etc.

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17) Touch screen:

It is the display screen of a device such as a smartphone, tablet, etc., that allows users to interact or provide inputs to the device by using their finger. Today, most of the electronic devices come with touchscreen as an alternative to a mouse for navigating a graphical user interface. For example, by touching, you can unlock your phone, open emails, open files, play videos, etc. Besides this, it is used in lots of devices such as Camera, Car GPS, Fitness machine, etc.

The concept of the touch screen was first introduced and published by E.A. Johnson in 1965. The first touch screen was developed at the beginning of the 1970s by CERN engineers Frank Beck and Bent Stumpe.

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18) VR:

VR stands for virtual reality. It is an artificial or virtual environment which is generated by computers. A person can interact with virtual objects of this artificial environment using some input devices such as headsets, gloves, headphones, etc. For example, he or she can find himself or herself walking on a beach, watching a football match, walking in the sky, etc., without actually doing all this.

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19) Webcam:

Any camera which is connected to a computer is called a webcam. The in-built camera provided on a computer can also be considered a webcam. It is an input device as it can take pictures, and can be used to record videos if required. The pictures and videos are stored in the computer memory and can be displayed on the screen if required. Although it works almost the same as the digital camera, it is different from a digital camera, as it is designed to take compact digital photos that can be uploaded easily on the webpages and shared with others through the internet.

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20) Biometric Devices:

Biometrics refers to a process in which a person is identified through his or her biological features such as fingerprints, eye cornea, face structure, etc. It is done by using biometric devices, which can be of different types based on their scanning features and abilities, such as:

i) Face Scanner:

It is designed to identify a person by scanning his or her face. It takes the face measurements of a person. For example, the distance between eyes, nose, and mouth, etc., accordingly, it confirms the identity of a person. Besides this, it is smart enough to differentiate between a person's picture and the real person.

ii) Hand Scanner:

The hand of a person can also be used to verify his or her identity as every person has a unique pattern of veins in the palm, just like fingerprints. This device takes advantage of this feature; it identifies a person by scanning the palm of his hand. It uses infrared light to scan veins' patterns and blood flowing in them. Palm is even more unique than fingerprints.

iii) Fingerprint Scanner:

It scans the fingerprints to identify people or for biometric authentication. This device is developed, keeping in mind the fact that no two persons in the world can have the same fingerprints. It is widely used in companies as a fingerprint attendance system to mark the attendance of employees. This type of scanners captures the pattern of valleys and ridges found on a finger and store it in the memory or database. When you press your finger on the given space, it verifies the identity by using its pattern-matching software.

iv) Retina or Iris Scanner:

It scans the retina or iris of a person's eye to confirm the identity. This device is more secure than others as it is next to impossible to copy the retina or iris. It works by mapping the retina's blood vessel patterns of the eye. The blood vessels of retina absorb light more easily as well as can be identified with appropriate lighting.

In this scan, a beam of low-energy infrared light falls on the retina through the scanner's eyepiece. Then, the software captures the network of blood vessels in the retina and uses it to verify a person's identity.

v) Voice Scanner:

It records the voice of a person and digitizes it to create a distinctive voice print or template. The voiceprints are stored in the database, and are used to verify the voice of a person to confirm his or her identity. The person is required to speak in the normal or same voice that was used to create a voice template. It is not much reliable as it can be misused using a tape recording.

Output Devices

The output device displays the result of the processing of raw data that is entered in the computer through an input device. There are a number of output devices that display output in different ways such as text, images, hard copies, and audio or video.

Some of the popular output devices are:

1. Monitor
• CRT Monitor
• LCD Monitor
• LED Monitor
• Plasma Monitor
2. Printer
• Impact Printers
1. Character Printers
1. Dot Matrix printers
2. Daisy Wheel printers
2. Line printers
1. Drum printers
2. Chain printers
• Non-impact printers
1. Laser printers
2. Inkjet printers
3. Projector

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1) Monitor

The monitor is the display unit or screen of the computer. It is the main output device that displays the processed data or information as text, images, audio or video.

The types of monitors are given below.

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i) CRT Monitor

CRT monitors are based on the cathode ray tubes. They are like vacuum tubes which produce images in the form of video signals. Cathode rays tube produces a beam of electrons through electron guns that strike on the inner phosphorescent surface of the screen to produce images on the screen. The monitor contains millions of phosphorus dots of red, green and blue color. These dots start to glow when struck by electron beams and this phenomenon is called cathodoluminescence.

The main components of a CRT monitor include the electron gun assembly, deflection plate assembly, fluorescent screen, glass envelope, and base.The front (outer surface) of the screen onto which images are produced is called the face plate. It is made up of fiber optics.

There are three electron beams that strike the screen: red, green, and blue. So, the colors which you see on the screen are the blends of red, blue and green lights.The magnetic field guides the beams of electrons. Although LCDs have replaced the CRT monitors, the CRT monitors are still used by graphics professionals because of their color quality.

ii) LCD Monitor

The LCD monitor is a flat panel screen that is compact and light-weight as compared to CRT monitors. It is based on liquid crystal display technology which is used in the screens of laptops, tablets, smart phones, etc. An LCD screen comprises two layers of polarized glass with a liquid crystal solution between them. When the light passes through the first layer, an electric current aligns the liquids crystals. The aligned liquid crystals allow a varying level of light to pass through the second layer to create images on the screen.

The LCD screen has a matrix of pixels that display the image on the screen.Old LCDs had passive-matrix screens in which individual pixels are controlled by sending a charge. A few electrical charges could be sent each second that made screens appear blurry when the images moved quickly on the screen.

Modern LCDs use active-matrix technology and contain thin film transistors (TFTs) with capacitors. This technology allows pixels to retain their charge. So, they don?t make screen blurry when images move fast on the screen as well as are more efficient than passive-matrix displays.

iii) LED monitor

The LED monitor is an improved version of an LCD monitor. It also has a flat panel display and uses liquid crystal display technology like the LCD monitors. The difference between them lies in the source of light to backlight the display. The LED monitor has many LED panels, and each panel has several LEDsto backlight the display, whereas the LCD monitors use cold cathode fluorescent light to backlight the display.Modern electronic devices such as mobile phones, LED TVs, laptop and computer screens, etc., use a LED display as it not only produces more brilliance and greater light intensity but also consumes less power.

iv) Plasma Monitor

The plasma monitor is also a flat panel display that is based on plasma display technology. It has small tiny cells between two glass panels. These cells contain mixtures of noble gases and a small amount of mercury. When voltage is applied, the gas in the cells turns into a plasma and emits ultraviolet light that creates images on the screen, i.e., the screen is illuminated by a tiny bit of plasma, a charged gas. Plasma displays are brighter than liquid crystal displays (LCD) and also offer a wide viewing angle than an LCD.

Plasma monitors provide high resolutions of up to 1920 X 1080, excellent contrast ratios, wide viewing angle, a high refresh rate and more. Thus, they offer a unique viewing experience while watching action movies, sports games, and more.

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2) Printer

A printer produces hard copies of the processed data. It enables the user, to print images, text or any other information onto the paper.

Based on the printing mechanism, the printers are of two types: Impact Printers and Non-impact Printers.

• Impact Printers: They are of two types:
1. Character Printers
1. Dot Matrix printers
2. Daisy Wheel printers
2. Line printers
1. Drum printers
2. Chain printers
• Non-impact printers: They are of two types:
1. Laser printers
2. Inkjet printers

Impact Printer

The impact printer uses a hammer or print head to print the character or images onto the paper. The hammer or print head strikes or presses an ink ribbon against the paper to print characters and images.

Impact printers are further divided into two types.

1. Character Printers
2. Line printers

A) Character Printers

Character printer prints a single character at a time or with a single stroke of the print head or hammer. It does not print one line at a time. Dot Matrix printer and Daisy Wheel printer are character printers. Today, these printers are not in much use due to their low speed and because only the text can be printed. The character printers are of two types, which are as follows:

i) Dot Matrix Printer

Dot Matrix Printer is an impact printer. The characters and images printed by it are the patterns of dots. These patterns are produced by striking the ink soaked ribbon against the paper with a print head. The print head contains pins that produce a pattern of dots on the paper to form the individual characters. The print head of a 24 pin dot matrix contains more pins than a 9 pin dot matrix printer, so it produces more dots which results in better printing of characters. To produce color output, the black ribbon can be changed with color stripes. The speed of Dot Matrix printers is around 200-500 characters per second.

ii) Daisy Wheel Printer

Daisy Wheel Printer was invented by David S. Lee at Diablo Data Systems.It consists of a wheel or disk that has spokes or extensions and looks like a daisy, so it is named Daisy Wheel printer. At the end of extensions, molded metal characters are mounted. To print a character the printer rotates the wheel, and when the desired character is on the print location the hammer hits disk and the extension hits the ink ribbon against the paper to create the impression. It cannot be used to print graphics and is often noisy and slow, i.e., the speed is very low around 25-50 characters per second. Due to these drawbacks,these printers have become obsolete.

B) Line Printers:

Line printer, which is also as a bar printer, prints one line at a time. It is a high-speed impact printer as it can print 500 to 3000 lines per minute. Drum printer and chain printer are examples of line printers.

i) Drum Printer:

Drum printer is a line printer that is made of a rotating drum to print characters. The drum has circular bands of characters on its surface. It has a separate hammer for each band of characters. When you print, the drum rotates, and when the desired character comes under the hammer, the hammer strikes the ink ribbon against the paper to print characters. The drum rotates at a very high speed and characters are printed by activating the appropriate hammers. Although all the characters are not printed at a time, they are printed at a very high speed. Furthermore, it can print only a predefined style as it has a specific set of characters. These printers are known to be very noisy due to the use of hammering techniques.

ii) Chain Printer:

Chain printer is a line printer that uses a rotating chain to print characters. The characters are embossed on the surface of the chain. The chain rotates horizontally around a set of hammers, for each print location one hammer is provided, i.e., the total number of hammers is equal to the total number of print positions.

The chain rotates at a very high speed and when the desired character comes at the print location, the corresponding hammer strikes the page against the ribbon and character on the chain.They can type 500 to 3000 lines per minute. They are also noisy due to the hammering action.

Non-Impact Printer:

Non-impact printers don't print characters or images by striking a print head or hammer on the ink ribbon placed against the paper. They print characters and images without direct physical contact between the paper and the printing machinery. These printers can print a complete page at a time, so they are also known as page printers. The common types of non-impact printers are Laser printer and Inkjet printer:

i) Laser Printer:

A laser printer is a non-impact printer that uses a laser beam to print the characters. The laser beam hits the drum, which is a photoreceptor and draws the image on the drum by altering electrical charges on the drum. The drum then rolls in toner, and the charged image on the drum picks the toner. The toner is then printed on the paper using heat and pressure. Once the document is printed, the drum loses the electric charge,and the remaining toner is collected. The laser printers use powdered toner for printing instead of liquid ink and produce quality print objects with a resolution of 600 dots per inch (dpi) or more.

ii) Inkjet Printer:

The inkjet printer is a non-impact printer that prints images and characters by spraying fine,ionized drops of ink. The print head has tiny nozzles to spray the ink. The printer head moves back and forth and sprays ionized drops of ink on the paper, which is fed through the printer. These drops pass through an electric field that guides the ink onto the paper to print correct images and characters.

An inkjet printer has cartridges that contain ink. Modern inkjet printers are color printers that have four cartridges containing different colors: Cyan, Magenta, Yellow, and Black. It is capable of printing high-quality images with different colors. It can produce print objects with a resolution of at least 300 dots per inch (dpi).

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3) Projector

A projector is an output device that enables the user to project the output onto a large surface such as a big screen or wall. It can be connected to a computer and similar devices to project their output onto a screen. It uses light and lenses to produce magnified texts, images, and videos. So, it is an ideal output device to give presentations or to teach a large number of people.

Modern projects (digital projectors) come with multiple input sources such as HDMI ports for newer equipment and VGA ports that support older devices. Some projectors are designed to support Wi-Fi and Bluetooth as well. They can be fixed onto the ceiling, placed on a stand, and more and are frequently used for classroom teaching, giving presentations, home cinemas, etc.

A digital projector can be of two types:

Liquid Crystal Display (LCD) digital projector: This type of digital projectors are very popular as they are lightweight and provide crisp output. An LCD projector uses transmissive technology to produce output. It allows the light source, which is a standard lamp, to pass through the three colored liquid crystal light panels. Some colors pass through the panels and some are blocked by the panels and thus images are on the screen.

Digital Light Processing (DLP) digital projector: It has a set of tiny mirrors, a separate mirror for each pixel of the image and thus provide high-quality images. These projectors are mostly used in theatres as they fulfill the requirement of high-quality video output.

Central Processing Unit (CPU)

A Central Processing Unit is also called a processor, central processor, or microprocessor. It carries out all the important functions of a computer. It receives instructions from both the hardware and active software and produces output accordingly. It stores all important programs like operating systems and application software. CPU also helps Input and output devices to communicate with each other. Owing to these features of CPU, it is often referred to as the brain of the computer.

CPU is installed or inserted into a CPU socket located on the motherboard. Furthermore, it is provided with a heat sink to absorb and dissipate heat to keep the CPU cool and functioning smoothly.

Generally, a CPU has three components:

• ALU (Arithmetic Logic Unit)
• Control Unit
• Memory or Storage Unit

Control Unit: It is the circuitry in the control unit, which makes use of electrical signals to instruct the computer system for executing already stored instructions. It takes instructions from memory and then decodes and executes these instructions. So, it controls and coordinates the functioning of all parts of the computer. The Control Unit's main task is to maintain and regulate the flow of information across the processor. It does not take part in processing and storing data.

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ALU: It is the arithmetic logic unit, which performs arithmetic and logical functions. Arithmetic functions include addition, subtraction, multiplication division, and comparisons. Logical functions mainly include selecting, comparing, and merging the data. A CPU may contain more than one ALU. Furthermore, ALUs can be used for maintaining timers that help run the computer.

Memory or Storage Unit/ Registers: It is called Random access memory (RAM). It temporarily stores data, programs, and intermediate and final results of processing. So, it acts as a temporary storage area that holds the data temporarily, which is used to run the computer.

What is CPU Clock Speed?

The clock speed of a CPU or a processor refers to the number of instructions it can process in a second. It is measured in gigahertz. For example, a CPU with a clock speed of 4.0 GHz means it can process 4 billion instructions in a second.

Types of CPU:

CPUs are mostly manufactured by Intel and AMD, each of which manufactures its own types of CPUs. In modern times, there are lots of CPU types in the market. Some of the basic types of CPUs are described below:

Single Core CPU: Single Core is the oldest type of computer CPU, which was used in the 1970s. It has only one core to process different operations. It can start only one operation at a time; the CPU switches back and forth between different sets of data streams when more than one program runs. So, it is not suitable for multitasking as the performance will be reduced if more than one application runs. The performance of these CPUs is mainly dependent on the clock speed. It is still used in various devices, such as smartphones.

Dual Core CPU: As the name suggests, Dual Core CPU contains two cores in a single Integrated Circuit (IC). Although each core has its own controller and cache, they are linked together to work as a single unit and thus can perform faster than the single-core processors and can handle multitasking more efficiently than Single Core processors.

Quad Core CPU: This type of CPU comes with two dual-core processors in one integrated circuit (IC) or chip. So, a quad-core processor is a chip that contains four independent units called cores. These cores read and execute instructions of CPU. The cores can run multiple instructions simultaneously, thereby increases the overall speed for programs that are compatible with parallel processing.

Quad Core CPU uses a technology that allows four independent processing units (cores) to run in parallel on a single chip. Thus by integrating multiple cores in a single CPU, higher performance can be generated without boosting the clock speed. However, the performance increases only when the computer's software supports multiprocessing. The software which supports multiprocessing divides the processing load between multiple processors instead of using one processor at a time.

History of CPU:

Some of the important events in the development of CPU since its invention till date are as follows:

• In 1823, Baron Jons Jackob Berzelius discovered silicon that is the main component of CPU till date.
• In 1903, Nikola Tesla got gates or switches patented, which are electrical logic circuits.
• In December 1947, John Bardeen, William Shockley, and Walter Brattain invented the first transistor at the Bell Laboratories and got it patented in 1948.
• In 1958, the first working integrated circuit was developed by Robert Noyce and Jack Kilby.
• In 1960, IBM established the first mass-production facility for transistors in New York.
• In 1968, Robert Noyce and Gordon Moore founded Intel Corporation.
• AMD (Advanced Micro Devices) was founded in May 1969.
• In 1971, Intel introduced the first microprocessor, the Intel 4004, with the help of Ted Hoff.
• In 1972, Intel introduced the 8008 processor; in 1976, Intel 8086 was introduced, and in June 1979, Intel 8088 was released.
• In 1979, a 16/32-bit processor, the Motorola 68000, was released. Later, it was used as a processor for the Apple Macintosh and Amiga computers.
• In 1987, Sun introduced the SPARC processor.
• In March 1991, AMD introduced the AM386 microprocessor family.
• In March 1993, Intel released the Pentium processor. In 1995, Cyrix introduced the Cx5x86 processor to give competition to Intel Pentium processors.
• In January 1999, Intel introduced the Celeron 366 MHz and 400 MHz processors.
• In April 2005, AMD introduced its first dual-core processor.
• In 2006, Intel introduced the Core 2 Duo processor.
• In 2007, Intel introduced different types of Core 2 Quad processors.
• In April 2008, Intel introduced the first series of Intel Atom processors, the Z5xx series. They were single-core processors with a 200 MHz GPU.
• In September 2009, Intel released the first Core i5 desktop processor with four cores.
• In January 2010, Intel released many processors such as Core 2 Quad processor Q9500, first Core i3 and i5 mobile processors, first Core i3 and i5 desktop processors. In the same year in July, it released the first Core i7 desktop processor with six cores.
• In June 2017, Intel introduced the first Core i9 desktop processor.
• In April 2018, Intel released the first Core i9 mobile processor.

Hardware

Hardware, which is abbreviated as HW, refers to all physical components of a computer system, including the devices connected to it. You cannot create a computer or use software without using hardware. The screen on which you are reading this information is also a hardware.

What is a hardware upgrade?

A hardware upgrade refers to a new hardware, or a replacement for the old one, or additional hardware developed to improve the performance of the existing hardware. A common example of a hardware upgrade is a RAM upgrade that increases the computer's total memory, and video card upgrade, where the old video card is removed and replaced with the new one.

Some of the commonly used hardware in your computer are described below:

1) Motherboard:

The motherboard is generally a thin circuit board that holds together almost all parts of a computer except input and output devices. All crucial hardware like CPU, memory, hard drive, and ports for input and output devices are located on the motherboard. It is the biggest circuit board in a computer chassis.

It allocates power to all hardware located on it and enables them to communicate with each other. It is meant to hold the computer's microprocessor chip and let other components connect to it. Each component that runs the computer or improves its performance is a part of the motherboard or connected to it through a slot or port.

There can be different types of motherboards based on the type and size of the computers. So, a specific motherboard can work only with specific types of processors and memory.

Components of a Motherboard:

CPU Slot: It is provided to install the CPU. It is a link between a microprocessor and a motherboard. It facilitates the use of CPU and prevents the damage when it is installed or removed. Furthermore, it is provided with a lock to prevent CPU movement and a heat sink to dissipate the extra heat.

RAM Slot: It is a memory slot or socket provided in the motherboard to insert or install the RAM (Random Access Memory). There can be two or more memory slots in a computer.

Expansion Slot: It is also called the bus slot or expansion port. It is a connection or port on the motherboard, which provides an installation point to connect a hardware expansion card, for example, you can purchase a video expansion card and install it into the expansion slot and then can install a new video card in the computer. Some of the common expansion slots in a computer are AGP, AMR, CNR, PCI, etc.

Capacitor: It is made of two conductive plates, and a thin insulator sandwiched between them. These parts are wrapped in a plastic container.

Inductor (Coil): It is an electromagnetic coil made of a conducting wire wrapped around an iron core. It acts as an inductor or electromagnet to store magnetic energy.

Northbridge: It is an integrated circuit that allows communications between the CPU interface, AGP, and memory. Furthermore, it also allows the southbridge chip to communicate with the RAM, CPU, and graphics controller.

USB Port: It allows you to connect hardware devices like mouse, keyboard to your computer.

PCI Slot: It stands for Peripheral Component Interconnect slot. It allows you to connect the PCI devices like modems, network hardware, sound, and video cards.

AGP Slot: It stands for Accelerated Graphics Port. It provides the slot to connect graphics cards.

Heat Sink: It absorbs and disperses the heat generated in the computer processor.

Power Connector: It is designed to supply power to the motherboard.

CMOS battery: It stands for complementary metal-oxide-semiconductor. It is a memory that stores the BIOS settings such as time, date, and hardware settings.

2) Monitor:

A monitor is the display unit of a computer on which the processed data, such as text, images, etc., is displayed. It comprises a screen circuity and the case which encloses this circuity. The monitor is also known as a visual display unit (VDU).

Types of Monitors:

1. CRT Monitor: It has cathode ray tubes which produce images in the form of video signals. Its main components are electron gun assembly, deflection plate assembly, glass envelope, fluorescent screen, and base.
2. LCD Monitor: It is a flat panel screen. It uses liquid crystal display technology to produce images on the screen. Advanced LEDs have thin-film transistors with capacitors and use active-matrix technology, which allows pixels to retain their charge.
3. LED Monitor: It is an advanced version of an LCD monitor. Unlike an LCD monitor, which uses cold cathode fluorescent light to backlight the display, it has LED panels, each of which has lots of LEDs to display the backlight.
4. Plasma Monitor: It uses plasma display technology that allows it to produce high resolutions of up to 1920 X 1080, wide viewing angle, a high refresh rate, outstanding contrast ration, and more.

3) Keyboard:

It is the most important input device of a computer. It is designed to allow you input text, characters, and other commands into a computer, desktop, tablet, etc. It comes with different sets of keys to enter numbers, characters, and perform various other functions like copy, paste, delete, enter, etc.

Types of Keyboards:

1. QWERTY Keyboards
2. AZERTY Keyboards
3. DVORAK Keyboards

4) Mouse:

It is a small handheld device designed to control or move the pointer (computer screen's cursor) in a GUI (graphical user interface). It allows you to point to or select objects on a computer's display screen. It is generally placed on a flat surface as we need to move it smoothly to control the pointer. Types of Mouse: Trackball mouse, Mechanical Mouse, Optical Mouse, Wireless Mouse, etc.

Main functions of a mouse:

• Move the cursor: It is the main function of the mouse; to move the cursor on the screen.
• Open or execute a program: It allows you to open a folder or document and execute a program. You are required to take the cursor on the folder and double click it to open it.
• Select: It allows you to select text, file, or any other object.
• Hovering: Hovering is an act of moving the mouse cursor over a clickable object. During hovering over an object, it displays information about the object without pressing any button of the mouse.
• Scroll: It allows you to scroll up or down while viewing a long webpage or document.

Parts of a mouse:

• Two buttons: A mouse is provided with two buttons for right click and left click.
• Scroll Wheel: A wheel located between the right and left buttons, which is used to scroll up and down and Zoom in and Zoom out in some applications like AutoCAD.
• Battery: A battery is required in a wireless mouse.
• Motion Detection Assembly: A mouse can have a trackball or an optical sensor to provide signals to the computer about the motion and location of the mouse.

Types of Computer Ports

A computer is a device that transforms data into meaningful information. It processes the input according to the set of instructions provided to it by the user and gives the desired output. As we know that we can connect multiple external devices with the computer system. Now, these devices are connected with the computer using Ports. The ports are the physical docking points present in the computer through which the external devices are connected using cables. Or in other words, a port is an interface between the motherboard and an external device of the computer. There are different types of ports available:

·        Serial port

·        Parallel port

·        USB port

·        PS/2 port

·        VGA port

·        Modem port 

·        FireWire Port 

·        Sockets

·        Infrared Port 

·        Game Port 

·        Digital Video Interface(DVI) Port

·        Ethernet Port

Now let us discuss these ports one by one:

1. Serial port(COM Port):

A serial port is also called a communication port and they are used for connection of external devices like a modem, mouse, or keyboard (basically in older PCs). Serial cables are cheaper to make in comparison to parallel cables and they are easier to shield from interference. There are two versions of it, which are 9 pin model and 25 pin model. It transmits data at 115 KB/sec. 

2. Parallel Port (LPT ports):

Parallel ports are generally used for connecting scanners and printers. It can send several bits at the same time as it uses parallel communication. Its data transfer speed is much higher in comparison with the serial port. It is a 25 pin model. It is also known as Printer Port or Line Printer Port.

3. USB (Universal Serial Bus):

In 1997 USB was first introduced. This can connect all kinds of external USB devices, like external hard disk, printer, scanner, mouse, keyboard, etc. There are minimum of two USB Ports provided in most of the computer systems. It is a kind of new type serial connection Port that is much faster than the old serial Ports and These USB Ports are much smarter and more versatile, as it allows the “daisy chaining” of up to 127 USB peripherals connected to one port. The data transfer rate in this is Data12 megabits per second. It also provides plug & plays communication.

4. PS/2 Port:

PS/2 ports are special ports used for connecting old computer keyboard and mouse. It was invented by IBM. In old computers, there are minimum of two PS/2 Ports, each for the keyboard and the mouse. It is a 6 pin mini Din connector.

5. VGA Port:

VGA ports also known as Video Graphic Array connector are those which connect the monitor to a computer’s video card. VGA port has 15 holes and it is similar to the serial port connector. But VGA Ports have holes in it and the serial port connector has pins in it.

6. Sockets:

Microphones and speakers are connected with the help of Sockets to the sound card of the computer.

7. FireWire Port:

The IEEE 1394 interface, which is developed in the late 1980s and early 1990s by Apple as FireWire. It can transfer large amount of data at very high speed. It is used to connect camcorders and video equipment to the computer. It comes up with three variants which are 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector, and 9-Pin FireWire 800 connector.

8. Infrared Port: 

An Infrared(IR) port is used to sends and receives infrared signals from other devices. It is a kind of wireless type port with a limited range of 5-10ft.

9. Game Port:

These ports are used previously to connect a joystick to a PC. But nowadays it is replaced by USB ports.

10. Modem Port:

As the name suggests, a Modem port is used to connects a PC’s modem to the telephone network.

11. Digital Video Interface(DVI) Port:

DVI Port is used to connects LCD(flat panel) monitor to the computer’s high-end video graphic cards and it is very popular among video card manufacturers.

12. Ethernet Port:

Ethernet Port helps to connect to a network and high-speed Internet(provided by LAN or other sources). It connects the network cable to a computer and resides in a Ethernet card. It provides a data travel speed of 10 Mb to 1000 Mb(megabits) per second.

Sample Questions

Question 1. What is the full form of USB?

(A) Universal Serial Bus

(B) Unedited System Bracket

(C) Unified Sound Bar

(D) Unique Sequencing Bus

Solution:

The correct option is A, i.e., Universal Serial bus.

Question 2. Ethernet Cables are used for ________?

(A) audio

(B) networking 

(C) internet

(D) Both b and c

Solution:

The correct option is both B and C

Because ethernet port helps to connect to a network and high speed Internet(provided by LAN or other source).

Question 3. Microphone and speakers are connected with the help of________?

(A) Ethernet cable

(B) Serial ports

(C) Sockets 

(D) None of the above

Solution:

The correct option is C, i.e., Sockets 

Microphone and speakers are connected with the help of Sockets to the sound card of the computer.

Question 4. FireWire Port  is developed in late 1980s and early 1990s by _______?

(A) Microsoft corporation Ltd.

(B) Apple

(C) Google

(D) Both Microsoft and Apple in collaboration

Solution:

The correct option is B, i.e., Apple

The IEEE 1394 interface, which is developed in late 1980s and early 1990s by Apple as FireWire. It can transfer large amount of data at very high speed. It is used to connect camcorders and video equipment to the computer. 

Question 5. In old computers, there are minimum how many PS/2 Ports are available?

(A) 2

(B) 5

(C) 1

(D) No PS/2 ports are present.

Solution:

The correct option is A, i.e., 2

PS/2 ports are special ports used for connecting old computer keyboard and mouse. In old computers there are minimum two PS/2 Ports, each for the keyboard and the mouse.

Question 6. Which are the Two versions of Serial ports?

(A) 15 pin model and 25 pin model 

(B) 9 pin model and 15 pin model

(C) 10 pin model and 20 pin model

(D) 9 pin model and 25 pin model

Solution: 

The correct option is D, i.e., 9 pin model and 25 pin model.

There are two versions of Serial ports, which are 9 pin model and 25 pin model. It transmits data at 115 KB/sec. 

 

 

Software

Software, which is abbreviated as SW or S/W, is a set of programs that enables the hardware to perform a specific task. All the programs that run the computer are software. The software can be of three types: system software, application software, and programming software.

1) System Software

The system software is the main software that runs the computer. When you turn on the computer, it activates the hardware and controls and coordinates their functioning. The application programs are also controlled by system software. An operating system is an example of system software.

i) Operating System:

An operating system is the system software that works as an interface to enable the user to communicate with the computer. It manages and coordinates the functioning of hardware and software of the computer. The commonly used operating systems are Microsoft Windows, Linux, and Apple Mac OS X.

Some other examples of system software include:

• BIOS: It stands for basic input output system. It is a type of system software, which is stored in Read Only Memory (ROM) located on the motherboard. However, in advanced computer systems, it is stored in flash memory. BIOS is the first software that gets activated when you turn on your computer system. It loads the drivers of the hard disk into memory as well as assists the operating system to load itself into the memory.
• Boot Program: Boot refers to starting up a computer. When you switch on the computer, the commands in the ROM are executed automatically to load the boot program into memory and execute its instructions. The BIOS program has a basic set of commands that enables the computer to perform the basic input/output instructions to start the computer.
• An assembler: It plays the role of a converter as it receives basic computer instructions and converts them into a pattern of bits. The processor uses these bits to perform basic operations.
• A device driver: This system software controls hardware devices connected to a computer. It enables the computer to use the hardware by providing an appropriate interface. The kernel of a Computer's CPU communicates with different hardware through this software. Operating systems generally come with most of the device drivers. If the operating system does not have a device driver for hardware, you have to install the device driver before using that hardware device.

2) Application Software:

Application software is a set of programs designed to perform a specific task. It does not control the working of a computer as it is designed for end-users. A computer can run without application software. Application software can be easily installed or uninstalled as required. It can be a single program or a collection of small programs. Microsoft Office Suite, Adobe Photoshop, and any other software like payroll software or income tax software are application software. As we know, they are designed to perform specific tasks. Accordingly, they can be of different types such as:

• Word Processing Software: This software allows users to create, edit, format, and manipulate the text and more. It offers lots of options for writing documents, creating images, and more. For example, MS Word, WordPad, Notepad, etc.
• Spreadsheet Software: It is designed to perform calculations, store data, create charts, etc. It has rows and columns, and the data is entered in the cell, which is an intersection of a row and column, e.g., Microsoft Excel.
• Multimedia Software: These software are developed to perform editing of video, audio, and text. It allows you to combine texts, videos, audio, and images. Thus, you can improve a text document by adding photos, animations, graphics, and charts through multimedia software. For example, VLC player, Window Media Player, etc.
• Enterprise Software: These software are developed for business operational functions. It is used in large organizations where the quantum of business is too large. It can be used for accounting, billing, order processing and more. For example, CRM (Customer Relationship Management), BI (Business Intelligence), ERP (Enterprise Resource Planning), SCM (Supply Chain Management), customer support system, and more.

3) Programming Software:

It is a set or collection of tools that help developers in writing other software or programs. It assists them in creating, debugging, and maintaining software or programs or applications. We can say that these are facilitator software that helps translate programming language such as Java, C++, Python, etc., into machine language code. So, it is not used by end-users. For example, compilers, linkers, debuggers, interpreters, text editors, etc. This software is also called a programming tool or software development tool.

Some examples of programming software include:

• Eclipse: It is a java language editor.
• Coda: It is a programming language editor for Mac.
• Notepad++: It is an open-source editor for windows.
• Sublime text: It is a cross-platform code editor for Linux, Mac, and Windows.

Operating System

As the name suggests, an operating system is a type of software without which you cannot operate or run a computer. It acts as an intermediary or translation system between computer hardware and application programs installed on the computer. In other words, you cannot directly use computer programs with computer hardware without having a medium to establish a connection between them.

Besides this, it is also an intermediary between the computer user and the computer hardware as it provides a standard user interface that you see on your computer screen after you switch on your computer. For example, the Windows and the Mac OS are also operating systems that provide a graphical interface with icons and pictures to enable users to access multiple files and applications simultaneously.

So, although the operating system is itself a program or software, it allows users to run other programs or applications on the system. We can say that is works behind the scenes to run your computer.

 

 

 

Major Functions of Operating System:

• Memory management: It manages both the primary and secondary memory such as RAM, ROM, hard disk, pen drive, etc. It checks and decides the allocations and deallocation of memory space to different processes. When a user interacts with a system, the CPU is supposed to read or write operations, in this case, OS decides the amount of memory to be allocated for loading the program instructions and data into RAM. After this program is terminated, the memory area is again free and is ready to be allocated to other programs by the OS.
• Processor Management: It facilitates processor management, where it decides the order for the processes to access the processor as well as decides the processing time to be allocated for each process. Besides this, it monitors the status of processes, frees the processor when a process is executed then allocates it to a new process.
• Device/ hardware management: The operating system also contains drivers to manage devices. A driver is a type of translation software that allows the operating system to communicate with devices, and there are different drivers for different devices as each device speaks a different language.
• Run software applications: It offers the environment to run or use software applications developed to perform specific tasks, for example, Ms Word, Ms Excel, Photoshop, etc.
• Data management: It helps in data management by offering and displaying directories for data management. You can view and manipulate files, folders, e.g., you can move, copy, name, or rename, delete a file or a folder.
• Evaluates the system's health: It gives us an idea about the performance of the hardware of the system. For example, you can see how busy the CPU is, how fast the data is retrieved from the hard disk, etc.
• Provides user interface: It acts as an interface between the user and the hardware. It can be a GUI where you can see and click elements on the screen to perform various tasks. It enables you to communicate with the computer even without knowing the computer's language.
• I/O management: It manages the input output devices and makes the I/O process smooth and effective. For example, it receives the input provided by the user through an input device and stores it in the main memory. Then it directs the CPU to process this input and accordingly provides the output through an output device such as a monitor.
• Security: It has a security module to protect the data or information stored in the memories of the computer against malware and unauthorized access. Thus, it not only manages your data but also helps to protect it.
• Time Management: It helps CPU in time management. The Kernel OS keeps checking the frequency of processes that requests CPU time. When two or more processes that are equally important compete for the CPU time, then the CPU time is sliced into segments and allocated to these processes in a round-robin fashion to prevent a single process from monopolizing the CPU.
• Deadlock Prevention: Sometimes a resource that is supposed to be shared by two or more processes is held by one process due to which the resource cannot continue. This situation is known as deadlock. The OS does not let this situation arise by carefully distributing the resources among the different processes.
• Interrupt Handling: OS also responds to interrupts, which are signals generated by a program or a device to seek the attention of the CPU. The OS checks the priority of the interrupt, and if it is more important than the currently running process, it stops the execution of the current process and preserves this state of CPU then executes the requested process. Thereafter the CPU returns to the same state where it was stopped.

Types of Operating System:

1) Batch Processing Operating System:

The interaction between a user and the computer does not occur in this system. The user is required to prepare jobs on punch cards in the form of batches and submit them to the computer operator. The computer operator sorts the jobs or programs and keeps similar programs or jobs in the same batch and run as a group to speed up processing. It is designed to execute one job at a time. Jobs are processed on a first-come, first-serve basis, i.e., in the order of their submission without any human intervention.

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For example, the credit card bill generated by banks is an example of batch processing. A separate bill is not generated for each credit card purchase, rather a single bill that includes all purchases in a month is generated through batch processing. The bill details are collected and held as a batch, and then it is processed to generate the bill at the end of the billing cycle. Similarly, in a payroll system, the salaries of employees of the company are calculated and generated through the batch processing system at the end of each month.

Advantages of Batch processing operating system:

• Repeated jobs can be completed easily without any human intervention
• Hardware or system support is not required to input data in batch systems
• It can work offline, so it causes less stress on the processor as it knows which task to process next and how long the task will last.
• It can be shared among multiple users.
• You can set the timing of batch jobs so that when the computer is not busy, it can start processing the batch jobs such as at night or any other free time.

Disadvantages of batch processing operating systems:

• You need to train the computer operators for using the batch system.
• It is not easy to debug this system.
• If any error occurs in one job, the other jobs may have to wait for an uncertain time.

2) Time Sharing Operating System:

As the name suggests, it enables multiple users located at different terminals to use a computer system and to share the processor's time simultaneously. In other words, each task gets time to get executed, and thus all tasks are executed smoothly.

Each user gets the processor's time as they get while using a single system. The duration of time allocated to a task is called quantum or time slice; when this duration is over, OS starts the next task.

Advantages of time sharing operating system:

• It reduces CPU idle time and thus makes it more productive.
• Each process gets the chance to use the CPU.
• It allowed different applications run simultaneously.

Disadvantages of time sharing operating system:

• It requires a special operating system as it consumes more resources.
• Switching between tasks may hang up the system as it serves lots of users and runs lots of applications at the same time, so it requires hardware with high specifications.
• It is less reliable.

3) Distributed Operating System:

It uses or runs on multiple independent processors (CPUs) to serve multiple users and multiple real-time applications. The communication between processors is established through many communication lines such as telephone lines and high-speed buses. The processors may differ from each other in terms of size and function.

The availability of powerful microprocessor and advanced communication technology have made it possible to design, develop, and use the distributed operating system. Besides this, it is an extension of a network operating system that supports a high level of communication and integration of machines on the network.

Advantages of distributed operating system:

• Its performance is higher than a single system as resources are being shared.
• If one system stops working, malfunctions, or breaks down, other nodes are not affected.
• Additional resources can be added easily.
• Shared access to resources like printer can be established.
• Delay in processing is reduced to a greater extent.
• Data sharing or exchange speed is high, owing to the use of electronic mail.

Disadvantages of distributed operating system:

• Security issue may arise due to sharing of resources
• Few messages may be lost in the system
• Higher bandwidth is required in case of handling a large amount of data
• Overloading issue may arise
• The performance may be low
• The languages which are used to set up a distributed system are not well defined yet
• They are very costly, so they are not easily available.

4)Network Operating System:

As the name suggests, this OS connects computers and devices to a local area network and manages network resources. The software in a NOS enables the devices of the network to share resources and communicate with each other. It runs on a server and allows shared access to printers, files, applications, files, and other networking resources and functions over a LAN. Besides this, all users in the network are aware of each other's underlying configuration and individual connections. Examples: Ms Windows Server 2003 and 2008, Linux, UNIX, Novell NetWare, Mac OS X, etc.

Advantages of network operating system:

• The servers are centralized that can be accessed remotely from distant locations and different systems.
• It is easy to integrate advanced and recent technologies and hardware in this system.

Disadvantages of network operating system:

• The servers used in the system may be expensive.
• The system depends on the central location and requires regular monitoring and maintenance.

5) Real-Time Operating System:

It is developed for real-time applications where data should be processed in a fixed, small duration of time. It is used in an environment where multiple processes are supposed to be accepted and processed in a short time. RTOS requires quick input and immediate response, e.g., in a petroleum refinery, if the temperate gets too high and crosses the threshold value, there should be an immediate response to this situation to avoid the explosion. Similarly, this system is used to control scientific instruments, missile launch systems, traffic lights control systems, air traffic control systems, etc.

This system is further divided into two types based on the time constraints:

Hard Real-Time Systems:

These are used for the applications where timing is critical or response time is a major factor; even a delay of a fraction of the second can result in a disaster. For example, airbags and automatic parachutes that open instantly in case of an accident. Besides this, these systems lack virtual memory.

Soft Real-Time Systems:

These are used for application where timing or response time is less critical. Here, the failure to meet the deadline may result in a degraded performance instead of a disaster. For example, video surveillance (cctv), video player, virtual reality, etc. Here, the deadlines are not critical for every task every time.

Advantages of real-time operating system:

• The output is more and quick owing to the maximum utilization of devices and system
• Task shifting is very quick, e.g., 3 microseconds, due to which it seems that several tasks are executed simultaneously
• Gives more importance to the currently running applications than the queued application
• It can be used in embedded systems like in transport and others.
• It is free of errors.
• Memory is allocated appropriately.

Disadvantages of real-time operating system:

• A fewer number of tasks can run simultaneously to avoid errors.
• It is not easy for a designer to write complex and difficult algorithms or proficient programs required to get the desired output.
• Specific drivers and interrupt signals are required to respond to interrupts quickly.
• It may be very expensive due to the involvement of the resources required to work.

 

 

 

 

 

Generations of Operating System:

The first generation (1945 to 1955):

It was the time before the Second World War when the digital computer was not developed, and there were calculating engines with mechanical relays at this point in time. Later mechanical relays were replaced by vacuum tubes as they were very slow. But, the performance issue was not resolved even with vacuum tubes, besides these machines were too bulky and large as there were made of tens of thousands of vacuum tubes.

Furthermore, each of the machines was designed, programmed, and maintained by a single group of people. The programming languages and operating systems were not known, and absolute machine language was being used for programming.

These systems were designed for numerical calculations. The programmer was required to sign up for a block of time and then insert his plug board into the computer. In the 1950s, punch cards were introduced, which improved the computer performance. It allowed programmers to write programs on punch cards and read them into the system; the rest of the procedure was the same.

The second generation (1955 to 1965):

This generation started with the introduction of transistors in the mid-1950s. The use of transistors made the computers more reliable, and they began to be sold to customers. These machines were called mainframes. Only the big organization and government corporations could afford it. In this machine, the programmer was required to write the program on a paper then punch it on cards. The card would be taken to the input room and handed over to an operator to get the output. The printer provides the output which was taken to the output room. These steps made it a time-consuming task. So, the batch system was adopted to address this issue.

In a batch system, the tasks were collected in a tray in the form of batches in the input room and read onto a magnetic tape, which was taken to the machine room, where it was mounted on a tape drive. Then using a special program, the operator was to read the first task or job from the tape and run it, and the output was generated onto a second tape. OS automatically read the next job from the tape, and Jobs were completed one by one. After the completion of the batch, the input and output tapes were taken off, and the next batch was started. The printouts were taken from the output tape. It was mainly used for engineering and scientific calculations. The first OS was used in this generation in computers was called FMS (Fortran Monitor System), and IBMSYS, and FORTRAN were used as a high-level language.

The third generation (1965 to 1979):

This generation began with the introduction of 360 family of computers of IBM in 1964. In this generation, transistors were replaced by silicon chips, and the operating system was developed for multiprogramming, some of them even supported batch processing, time sharing, real-time processing, at the same time.

The fourth generation operating system (1979 to Present):

This generation of OS started with the introduction of personal computers and workstations. Chips that contain thousands of transistors were introduced in this generation that made possible the development of personal computers that supported the growth of networks and thus the development of network operating systems and distributed operating systems. DOS, Linux, and window operation systems were are few examples of OS of this generation.

Computer Memory

The computer memory holds the data and instructions needed to process raw data and produce output. The computer memory is divided into large number of small parts known as cells. Each cell has a unique address which varies from 0 to memory size minus one.

Computer memory is of two types: Volatile (RAM) and Non-volatile (ROM). The secondary memory (hard disk) is referred as storage not memory.

But, if we categorize memory on behalf of space or location, it is of four types:

• Register memory
• Cache memory
• Primary memory
• Secondary memory

Register Memory

Register memory is the smallest and fastest memory in a computer. It is not a part of the main memory and is located in the CPU in the form of registers, which are the smallest data holding elements. A register temporarily holds frequently used data, instructions, and memory address that are to be used by CPU. They hold instructions that are currently processed by the CPU. All data is required to pass through registers before it can be processed. So, they are used by CPU to process the data entered by the users.

Registers hold a small amount of data around 32 bits to 64 bits. The speed of a CPU depends on the number and size (no. of bits) of registers that are built into the CPU. Registers can be of different types based on their uses. Some of the widely used Registers include Accumulator or AC, Data Register or DR, the Address Register or AR, Program Counter (PC), I/O Address Register, and more.

Types and Functions of Computer Registers:

• Data Register: It is a 16-bit register, which is used to store operands (variables) to be operated by the processor. It temporarily stores data, which is being transmitted to or received from a peripheral device.
• Program Counter (PC): It holds the address of the memory location of the next instruction, which is to be fetched after the current instruction is completed. So, it is used to maintain the path of execution of the different programs and thus executes the programs one by one, when the previous instruction gets completed.
• Instructor Register: It is a 16-bit register. It stores the instruction which is fetched from the main memory. So, it is used to hold instruction codes, which are to be executed. The Control Unit takes instruction from Instructor Register, then decodes and executes it.
• Accumulator Register: It is a 16-bit register, which is used to store the results produced by the system. For example, the results generated by CPU after the processing are stored in the AC register.
• Address Register: It is a 12-bit register that stores the address of a memory location where instructions or data is stored in the memory.
• I/O Address Register: Its job is to specify the address of a particular I/O device.
• I/O Buffer Register: Its job is to exchange the data between an I/O module and the CPU.

Cache Memory

Cache memory is a high-speed memory, which is small in size but faster than the main memory (RAM). The CPU can access it more quickly than the primary memory. So, it is used to synchronize with high-speed CPU and to improve its performance.

Cache memory can only be accessed by CPU. It can be a reserved part of the main memory or a storage device outside the CPU. It holds the data and programs which are frequently used by the CPU. So, it makes sure that the data is instantly available for CPU whenever the CPU needs this data. In other words, if the CPU finds the required data or instructions in the cache memory, it doesn't need to access the primary memory (RAM). Thus, by acting as a buffer between RAM and CPU, it speeds up the system performance.

Types of Cache Memory:

L1: It is the first level of cache memory, which is called Level 1 cache or L1 cache. In this type of cache memory, a small amount of memory is present inside the CPU itself. If a CPU has four cores (quad core cpu), then each core will have its own level 1 cache. As this memory is present in the CPU, it can work at the same speed as of the CPU. The size of this memory ranges from 2KB to 64 KB. The L1 cache further has two types of caches: Instruction cache, which stores instructions required by the CPU, and the data cache that stores the data required by the CPU.

L2: This cache is known as Level 2 cache or L2 cache. This level 2 cache may be inside the CPU or outside the CPU. All the cores of a CPU can have their own separate level 2 cache, or they can share one L2 cache among themselves. In case it is outside the CPU, it is connected with the CPU with a very high-speed bus. The memory size of this cache is in the range of 256 KB to the 512 KB. In terms of speed, they are slower than the L1 cache.

L3: It is known as Level 3 cache or L3 cache. This cache is not present in all the processors; some high-end processors may have this type of cache. This cache is used to enhance the performance of Level 1 and Level 2 cache. It is located outside the CPU and is shared by all the cores of a CPU. Its memory size ranges from 1 MB to 8 MB. Although it is slower than L1 and L2 cache, it is faster than Random Access Memory (RAM).

How does cache memory work with CPU?

When CPU needs the data, first of all, it looks inside the L1 cache. If it does not find anything in L1, it looks inside the L2 cache. If again, it does not find the data in L2 cache, it looks into the L3 cache. If data is found in the cache memory, then it is known as a cache hit. On the contrary, if data is not found inside the cache, it is called a cache miss.

If data is not available in any of the cache memories, it looks inside the Random Access Memory (RAM). If RAM also does not have the data, then it will get that data from the Hard Disk Drive.

So, when a computer is started for the first time, or an application is opened for the first time, data is not available in cache memory or in RAM. In this case, the CPU gets the data directly from the hard disk drive. Thereafter, when you start your computer or open an application, CPU can get that data from cache memory or RAM.