Computer Fundamentals Unit 1 Notes PDF

Computer Fundamentals Unit 1 Notes Discuss the definition of Computers, History and Generations of Computers, Characteristics of computer, and Classification of Computers. (C2: Comprehension) Explain a Fundamental Block diagram of Computer.: CPU, Input & Output Unit (C2: Comprehension) Generalize th...

Computer Fundamentals Unit 1 Notes Discuss the definition of Computers, History and Generations of Computers, Characteristics of computer, and Classification of Computers. (C2: Comprehension) Explain a Fundamental Block diagram of Computer.: CPU, Input & Output Unit (C2: Comprehension) Generalize the concept of the Input devices, Output devices, Discuss the following terms: Types of printers, Memory, CD-ROM, Hard disk, Floppy disk. (C2: Comprehension) 1. What is a computer? In the modern world, computers have become an integral part of our daily lives, revolutionizing the way we work, communicate, and entertain ourselves. From desktops to laptops, tablets to smartphones, computers come in various forms, yet many people are still unfamiliar with their inner workings and potential. Definition of Computer A computer is an electronic device wherein we need to input raw data to be processed with a set of programs to produce a desirable output. Computers have the ability to store, process, and manipulate data. The term “computer” is derived from the Latin word “computare,” which means “to calculate.” A computer is made to run programs and apps by using both hardware and software. It also has a memory to store data, programs, and what they produce. 10 Different Definitions of a Computer 1. Electronic device: A computer in generally termed as an electronic device that transmits data using electronic facilities and software programs 2. Data processor: The computer processes data using arithmetic, logical and input/output operations 3. Information machine: By processing multiple algorithms and computations, a computer gets up a meaningful definition to what we have searched 4. Digital device: A computer manipulates, stores, and retrieves data represented in binary form to present it can understand manner for humans 5. Universal machine: A computer is also known as a universal machine as it can solve problems of people by understanding their program and not by any other factor 6. Communication tool: Computer is a universal communication tool as it provides the facility to connect, collaborate or transfer of messages through a network and the internet 7. Problem solver: Computers are designed to solve problems that can affect or slow down daily human tasks, therefore, it is a problem solver 8. Multifunctional device: Multifunctionality is the power of a computer as it can perform more than 1 task at a time and that too with utmost perfection 9. Information processor: Computers are fitted with processors that process raw data into organized and meaningful outputs 10. Automation tool: Computers have the functionality to automate the repetitive tasks and enhance productive by saving time  2. History and Generations of Computers Basic Terms Vacuum tube – an electronic device that controls the flow of electrons in a vacuum. It used as a switch, amplifier, or display screen in many older model radios, televisions, computers, etc. Transistor – an electronic component that can be used as an amplifier or as a switch. It is used to control the flow of electricity in radios, televisions, computers, etc. Integrated circuit (IC) – a small electronic circuit printed on a chip (usually made of silicon) that contains many its own circuit elements (e.g. transistors, diodes, resistors, etc.). Microprocessor – an electronic component held on an integrated circuit that contains a computer’s central processing unit (CPU) and other associated circuits. CPU (central processing unit) – It is often referred to as the brain or engine of a computer where most of the processing and operations take place (CPU is part of a microprocessor). Magnetic drum – a cylinder coated with magnetic material, on which data and programs can be stored. Magnetic core – uses arrays of small rings of magnetized material called cores to store information. Machine language – a low-level programming language comprised of a collection of binary digits (ones and zeros) that the computer can read and understand. Assembly language is like the machine language that a computer can understand, except that assembly language uses abbreviated words (e.g. ADD, SUB, DIV…) in place of numbers (0s and 1s). Memory – a physical device that is used to store data, information and program in a computer. Artificial intelligence (AI) – an area of computer science that deals with the simulation and creation of intelligent machines or intelligent behave in computers (they think, learn, work, and react like humans). First Generation of Computers Classification of generations of computers The evolution of computer technology is often divided into five generations. Five Generations of Computers Generations of computers Generations timeline Evolving hardware First generation 1940s-1950s Vacuum tube based Second generation 1950s-1960s Transistor based Third generation 1960s-1970s Integrated circuit based Fourth generation 1970s-present Microprocessor based Fifth generation The present and the future Artificial intelligence based The main characteristics of first generation of computers (1940s-1950s) Main electronic component – vacuum tube Main memory – magnetic drums and magnetic tapes Programming language – machine language Power – consume a lot of electricity and generate a lot of heat. Speed and size – very slow and very large in size (often taking up entire room).  Input/output devices – punched cards and paper tape. Examples – ENIAC, UNIVAC1, IBM 650, IBM 701, etc. Quantity – there were about 100 different vacuum tube computers produced between 1942 and1963. Second Generation of Computers The main characteristics of second generation of computers (1950s-1960s) Main electronic component – transistor Memory – magnetic core and magnetic tape / disk Programming language – assembly language Power and size – low power consumption, generated less heat, and smaller in size (in comparison with the first generation computers). Speed – improvement of speed and reliability (in comparison with the first generation computers). Input/output devices – punched cards and magnetic tape. Examples – IBM 1401, IBM 7090 and 7094, UNIVAC 1107, etc. Third Generation of Computers The main characteristics of third generation of computers (1960s-1970s) Main electronic component – integrated circuits (ICs) Memory – large magnetic core, magnetic tape / disk Programming language – high level language (FORTRAN, BASIC, Pascal, COBOL, C, etc.) Size – smaller, cheaper, and more efficient than second generation computers (they were called minicomputers). Speed – improvement of speed and reliability (in comparison with the second generation computers). Input / output devices – magnetic tape, keyboard, monitor, printer, etc. Examples – IBM 360, IBM 370, PDP-11, UNIVAC 1108, etc. Fourth Generation of Computers The main characteristics of fourth generation of computers (1970s-present)  Main electronic component – very large-scale integration (VLSI) and microprocessor. VLSI– thousands of transistors on a single microchip. Memory – semiconductor memory (such as RAM, ROM, etc.) o RAM (random-access memory) – a type of data storage (memory element) used in computers that temporary stores of programs and data (volatile: its contents are lost when the computer is turned off). o ROM (read-only memory) – a type of data storage used in computers that permanently stores data and programs (non-volatile: its contents are retained even when the computer is turned off). Programming language – high level language (Python, C#, Java, JavaScript, Rust, Kotlin, etc.). o A mix of both third- and fourth-generation languages Size – smaller, cheaper and more efficient than third generation computers. Speed – improvement of speed, accuracy, and reliability (in comparison with the third generation computers). Input / output devices – keyboard, pointing devices, optical scanning, monitor, printer, etc. Network – a group of two or more computer systems linked together. Examples – IBM PC, STAR 1000, APPLE II, Apple Macintosh, etc. Fifth Generation of Computers The main characteristics of fifth generation of computers (the present and the future) Main electronic component: based on artificial intelligence, uses the Ultra Large-Scale Integration (ULSI) technology and parallel processing method. o ULSI – millions of transistors on a single microchip o Parallel processing method – use two or more microprocessors to run tasks simultaneously.  Language – understand natural language (human language). Power – consume less power and generate less heat. Speed – remarkable improvement of speed, accuracy and reliability (in comparison with the fourth generation computers). Size – portable and small in size, and have a huge storage capacity. Input / output device – keyboard, monitor, mouse, trackpad (or touchpad), touchscreen, pen, speech input (recognise voice / speech), light scanner, printer, etc. Example – desktops, laptops, tablets, smartphones, etc. The computer – this amazing technology went from a government/business-only technology to being everywhere from people’s homes, work places, to people’s pockets in less than 100 years. 3. Characteristics of Computer Computers are now an integral part of our daily lives, from managing student records in schools to handling patient records in hospitals. They have significantly simplified our tasks. Now, we can quickly access stored data and solve complex problems in just seconds. Some of the characteristics of Computers are listed below- Saves Time: A computer saves time by completing tasks quicker and more efficiently. For example, it can solve big complex problems within seconds which can save many minutes of ours. Internet: Computers connect us to the internet which can help us to know important information from around the world, it can connect us with people from around the world through social networking sites, etc. Storage: The computer gives us enough storage space that can be used to store a large amount of data including your projects, ebooks, documents, movies, pictures, songs, etc. Entertainment: Computers are also a big source of entertainment as you can play games, listen to songs, watch movies, and can also use social networking sites. Organized Data: It not only stores the data for you for also organizes the data for you. You can create different folders for different types of data and can easily access them when required. Helps the physically challenged: Computers are a big boon for the physically challenged people as Stephen Hawking, who was not able to speak used the computer to speak. It also can be used to help blind people by installing special software to read what is on the screen. Features of Computer We have discussed a few points that will highlight the different features of computers. These features collectively contribute to the versatility and functionality of computers. Processing Power: Computers can execute instructions and perform calculations quickly. Storage Capacity: They can store vast amounts of data, from documents to multimedia files. Memory (RAM): Temporary storage used for actively running programs and processes. Input Devices: Keyboards, mouse, and other peripherals allow users to input data. Output Data: Monitors, printers, and speakers display or produce results.  Upgradability: Components like RAM, storage, and graphics cards can be upgraded. Portability: Laptops and tablets offer mobility compared to desktop computers. User Interface: Graphical user interfaces (GUIs) or command-line interfaces for interaction. Security Features: Passwords, firewalls, and antivirus tools protect against unauthorized access. Power Management: Features to optimize energy consumption. 4. Classification of Computers The computer systems can be classified on the following basis: 1. On the basis of size. 2. On the basis of functionality. 3. On the basis of data handling. Classification on the basis of size Super computers : The super computers are the most high performing system. A supercomputer is a computer with a high level of performance compared to a general-purpose computer. The actual Performance of a supercomputer is measured in FLOPS instead of MIPS. All of the world’s fastest 500 supercomputers run Linux-based operating systems. Additional research is being conducted in China, the US, the EU, Taiwan and Japan to build even faster, more high performing and more technologically superior supercomputers. Supercomputers actually play an important role in the field of computation, and are used for intensive computation tasks in various fields, including quantum mechanics, weather forecasting, climate research, oil and gas exploration, molecular modeling, and physical simulations. and also Throughout the history, supercomputers have been essential in the field of the cryptanalysis. eg: PARAM, jaguar, roadrunner. Mainframe computers : These are commonly called as big iron, they are usually used by big organisations for bulk data processing such as statistics, census data processing, transaction processing and are widely used as the servers as these systems has a higher processing capability as compared to the other classes of computers, most of these mainframe architectures were established in 1960s, the research and development worked continuously over the years and the mainframes of today are far more better than the earlier ones, in size, capacity and efficiency. Eg: IBM z Series, System z9 and System z10 servers. Mini computers : These computers came into the market in mid 1960s and were sold at a much cheaper price than the main frames, they were actually designed for control, instrumentation, human interaction, and communication switching as distinct from calculation and record keeping, later they became very popular for personal uses with evolution. In the 60s to describe the smaller computers that became possible with the use of transistors and core memory technologies, minimal instructions sets and less expensive peripherals such as the ubiquitous Teletype Model 33 ASR.They usually took up one or a few inch rack cabinets, compared with the large mainframes that could fill a room, there was a new term “MINICOMPUTERS” coined Eg: Personal Laptop, PC etc. Micro computers : A microcomputer is a small, relatively inexpensive computer with a microprocessor as its CPU. It includes a microprocessor, memory, and minimal I/O circuitry mounted on a single printed circuit board.The previous to these computers, mainframes and minicomputers, were comparatively much larger, hard to maintain and more expensive. They actually formed the foundation for present day microcomputers and smart gadgets that we use in day to day life. Eg: Tablets, Smartwatches. Classification on the basis of functionality Servers : Servers are nothing but dedicated computers which are set-up to offer some services to the clients. They are named depending on the type of service they offered. Eg: security server, database server. Workstation : Those are the computers designed to primarily to be used by single user at a time. They run multi-user operating systems. They are the ones which we use for our day to day personal / commercial work. Information Appliances : They are the portable devices which are designed to perform a limited set of tasks like basic calculations, playing multimedia, browsing internet etc. They are generally referred as the mobile devices. They have very limited memory and flexibility and generally run on “as-is” basis. Embedded computers : They are the computing devices which are used in other machines to serve limited set of requirements. They follow instructions from the non-volatile memory and they are not required to execute reboot or reset. The processing units used in such device work to those basic requirements only and are different from the ones that are used in personal computers- better known as workstations. Classification on the basis of data handling Analog : An analog computer is a form of computer that uses the continuously-changeable aspects of physical fact such as electrical, mechanical, or hydraulic quantities to model the problem being solved. Any thing that is variable with respect to time and continuous can be claimed as analog just like an analog clock measures time by means of the distance traveled for the spokes of the clock around the circular dial. Digital : A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system of “0” and “1”, “Computer capable of solving problems by processing information expressed in discrete form. from manipulation of the combinations of the binary digits, it can perform mathematical calculations, organize and analyze data, control industrial and other processes, and simulate dynamic systems such as global weather patterns. Hybrid : A computer that processes both analog and digital data, Hybrid computer is a digital computer that accepts analog signals, converts them to digital and processes them in digital form. 5. Explain a Fundamental Block diagram of Computer.: CPU, Input & Output Unit Input All the data received by the computer goes through the input unit. The input unit comprises different devices like a mouse, keyboard, scanner, etc. In other words, each of these devices acts as a mediator between the users and the computer. The data that is to be processed is put through the input unit. The computer accepts the raw data in binary form. It then processes the data and produces the desired output. Major Functions of the Input Unit The 3 major functions of the input unit are- Take the data to be processed by the user. Convert the given data into machine-readable form. And then, transmit the converted data into the main memory of the computer. The sole purpose is to connect the user and the computer. In addition, this creates easy communication between them. CPU – Central Processing Unit Central Processing Unit or the CPU, is the brain of the computer. It works the same way a human brain works. As the brain controls all human activities, similarly the CPU controls all the tasks. Moreover, the CPU conducts all the arithmetical and logical operations in the computer. Now the CPU comprises of two units, namely – ALU (Arithmetic Logic Unit) and CU (Control Unit). Both of these units work in sync. The CPU processes the data as a whole. Let us see what particular tasks are assigned to both units. ALU – Arithmetic Logic Unit The Arithmetic Logic Unit is made of two terms, arithmetic and logic. There are two primary functions that this unit performs. Data is inserted through the input unit into the primary memory. Performs the basic arithmetical operations on it, like addition, subtraction, multiplication, and division. It performs all sorts of calculations required on the data. Then, it sends back data to the storage. The unit is also responsible for performing logical operations like AND, OR, Equal to, Less than, etc. In addition to this, it conducts merging, sorting, and selection of the given data. CU – Control Unit The control unit as the name suggests is the controller of all the activities/tasks and operations. All this is performed inside the computer. The memory unit sends a set of instructions to the control unit. Then the control unit in turn converts those instructions. After that these instructions are converted to control signals. These control signals help in prioritizing and scheduling activities. Thus, the control unit coordinates the tasks inside the computer in sync with the input and output units. Memory Unit All the data that has to be processed or has been processed is stored in the memory unit. The memory unit acts as a hub of all the data. It transmits it to the required part of the computer whenever necessary. The memory unit works in sync with the CPU. This helps in faster accessing and processing of the data. Thus, making tasks easier and quicker. Types of Computer Memory There are two types of computer memory- Primary Memory This type of memory cannot store a vast amount of data. Therefore, it is only used to store recent data. The data stored in this is temporary. It can get erased once the power is switched off. Therefore, is also called temporary memory or main memory. RAM stands for Random Access Memory. It is an example of primary memory. This memory is directly accessible by the CPU. It is used for reading and writing purposes. For data to be processed, it has to be first transferred to the RAM and then to the CPU. Secondary Memory As explained above, the primary memory stores temporary data. Thus it cannot be accessed in the future. For permanent storage purposes, secondary memory is used. It is also called permanent memory or auxiliary memory. The hard disk is an example of secondary memory. Even in a power failure data does not get erased easily. Output There is nothing to be amazed by what the output unit is used for. All the information sent to the computer once processed is received by the user through the output unit. Devices like printers, monitors, projectors, etc. all come under the output unit. The output unit displays the data either in the form of a soft copy or a hard copy. The printer is for the hard copy. The monitor is for the display. The output unit accepts the data in binary form from the computer. It then converts it into a readable form for the user. 6. Generalize the concept of the Input devices What are input devices? As their name suggests, these devices send information to the computer system. Once the computer receives the information via an input device, the computer then processes that information via the CPU. The information is then displayed and made available via an output device. Let us list some necessary input devices: o Keyboard o Mouse o Joy Stick o Light pen o Track Ball o Scanner o Graphic Tablet o Microphone o Magnetic Ink Card Reader (MICR) o Optical Character Reader (OCR) o Bar Code Reader o Optical Mark Reader (OMR) 1. Keyboard A keyboard is undoubtedly the most popular input device. A lot of the data we input into a computer is done through a keyboard. The main set of keys on a keyboard include: o Typing keys – These include the alphabet and digit keys. o Numeric Keypad- As its name suggests, it is used to enter numeric data and consists of 17 keys. o Function keys – These are a set of 12 keys. Each key has a specific function to perform. o Control keys – These are meant for cursor and screen control. Broadly, control keys include the Arrow keys, Home, Insert, Delete, Page Up, Page Down, Control, Alternate, and Escape Keys. o Special Purpose Keys – These keys include Enter, Shift, Num Lock, Space Bar, Tab, and Print Screen with a particular function. 2. Mouse A popular pointing device, it helps control the cursor. It has a left and a right button. The primary purpose of the mouse is to send appropriate signals to the CPU. The first person to whom the creation of a working mouse is credited is Douglas C. Engelbart, in 1963. The original mouse used a rollerball under the mouse’s surface; most optical mice today use a laser. 3. Joystick C.B. Mirick is credited with inventing the first joystick utilized at the US Naval Research Laboratory. Similar to a mouse, a joystick serves as a pointing device, allowing the movement of a cursor. The joystick can be maneuvered in all directions. Notably, the cursor continues moving toward the joystick unless it is in an upright position, distinguishing its operation from that of a mouse, where the cursor moves with the mouse’s motion. Joysticks find significant applications in areas such as computer-aided design (CAD) and gaming.  4. Trackball A cursor control device, the trackball, was invented in 1952 by Tom Cranston and Fred Longstaff. It is used in some keyboards as well as older versions of the mouse. Essentially, it has a socket holding a ball with sensors that can detect the ball’s rotation. 5. Scanner This input device resembles a photocopy machine and is used when transferring information on paper onto the computer. What the scanner does is that it captures the images from the paper and converts them into their digital form.  6. Digitizer Like a scanner, a digitizer converts analog information into digital. A digitizer can then convert signals from the television or camera. It can convert graphics into binary inputs. A graphic tablet is often used as a digitizer. 7. Microphone Through this input device, you can input sound into the computer system. Using a microphone, both live audio and pre-recorded audio can be fed into the computer-based recorder. The microphone functions by converting acoustic energy into an electric signal. Its low cost, compact size, and high sensitivity make it advantageous. Additionally, this device can be utilized for  dictating text instead of typing it via the keyboard. 8. Magnetic Ink Card Reader (MICR) You may have encountered this device being used in banks to process cheques. The reader scans both the bank’s code and cheque numbers, ensuring a swift and error-free process. 9. Optical Character Reader (OCR) An input device, this one is used to read printed text. What it does is scan the text and convert it into machine-readable code. The text is then stored in the system’s memory. 10. Bar Code Readers  You would have seen its use at a supermarket or a mall. A bar code reader reads bar-coded data generally used to label goods. The barcode reader may be a handheld scanner or a stationary one. What it essentially does is that it scans the barcode image and then converts it into an alphanumeric value. 11. Optical Mark Reader (OMR) In giving certain exams, you may have been told to shade a multiple-choice answer. The answer would then be read with the help of an Optical Mark Reader. Not only would the correction of such answer sheets be quick, but it would be error-free, too. 12. Light Pen Invented around 1955 as a part of the Whirlwind Project at MIT, a light pen contains a light- sensitive detector. When you point the Light Pen to an object, its light-sensitive tip detects the object and then sends the signals to the CPU. Its use today is limited since it is not compatible with LCD screens. 7. Generalize the concept of the Output devices What is an Output Device? The output devices are used to convert the computer produced output into human-readable form. The output device takes information from the computer and presents it in the form of projection, display, or on paper. Difference between Input and Output Devices Input devices – The computer input devices convert the data entered by the user into binary language and send it to the computer to process it. For example, keyboards, mice, scanners, etc. Output devices – The output devices are peripheral devices that are used to convert the output processed by the computer into human-readable form. These devices either display the output on the screen, print on paper, or through any other form. Examples: printer, monitor, projector, headphones, etc. Examples of Output Devices of Computer Let us look at some of the output devices one by one. Monitor The monitor is an output device that displays the output in the form of images on a digital screen. The images formed are made up of millions of tiny dots called pixels. The more pixels, the better resolution of the image is. Earlier monitors had screens made of CRT, but are now replaced by flat panel displays. Let us understand how both are different from each other- CRT – The CRT or cathode ray tube is the structure behind the screen. That helps to display characters and images on the monitor. The display side consists of a phosphorescent screen. The screen lights up when a beam of electrons hits the screen from the cathode filament. The electrons are deflected and accelerated and that is how the images are formed on the screen. However, the CRT based monitors have their disadvantages, which include- 1. They require a large space due to the presence of a vacuum tube of the CRT. 2. They consume high power because of the heating of the cathode filament to release electrons. Due to these drawbacks, flat panel displays came into the picture. Flat-panel display – The flat panel displays are much lighter, thinner, and consume less power than the traditional CRT monitors. They are wearable like digital wristwatches and portable like laptops or calculators. This gave the flat panel displays an upper hand over CRTs. They broadly divided into- Emissive Display – The LEDs and plasma panel displays are a few examples of emissive displays, as in these the electrical energy gets converted into light energy. Non-emissive Display: the LCDs are non-emissive displays, as optical effects are used to convert light sources like sunlight to images. Printers Printers are another peripheral device used as output devices. The output from the computer is achieved on paper from the printer. The data gets printed on paper which can be both colored or black and white, an image, text, or even both. The printer can be majorly divided into two types- Impact printers – These printers work by having direct contact with the ink ribbon and paper. Due to this, the noise produced by these printers resembles that of a typewriter. Non-Impact printers – These printers work with technologies like inkjet, laser, electrostatic, xerographic, etc. These printers work silently and are much faster than the impact ones. Headphone The audio or sound produced by the computer is in the form of electric signals. These are perceived by us in the form of sound using the output device, headphones. The headphones are transducers that convert electrical energy into mechanical energy and thus help us listen to songs and recordings on the computer. The best thing is that they are light and thus portable, unlike heavy computer speakers. Computer Speaker Computer speakers are output device that works the same way as a headphone. They make our entertainment experience easier. We can watch movies, listen to music, recordings, or any audio with help of speakers. They can be used instead of headphones when multiple people want to listen to the audio. Projector The projector is an output device, that is used to project the image displayed on the computer monitor on a large wall or screen. This is a good option when the output is to be shown to a large number of people. It can be used to watch movies with friends, or show a presentation in a group meeting. The projector is connected to the computer using HDMI cables or VGA cables. The output from the computer is taken as input by the projector. Nowadays, traditional blackboards are also getting replaced by smart screens, which use projectors to display images and videos to the students for better understanding. GPS (Global Positioning System) The GPS device is a device used for navigation purposes that are connected to satellites and help in determining the location of the device connected. Think it of as an interactive screen that displays our device’s location on a map. This map is movable and can be used to find any location on the Earth. Sound card The sound card is an expansion card used in computers to connect input-output devices. It is either integrated. The sound card audio ports are visible on the side or back of the computer, where you can connect any device like a keyboard, headphones, speakers, and microphones. Each sport is specifically designed for each type of device. The primary function of the soundcard is used to play any audio, record audio, connect joysticks or controllers for gaming purposes, and speakers to listen to music or any sound. Plotter A plotter is an output device that works similarly to a printer, but for large vector graphics. The lines are made on paper using a pen or any other such tool mechanically by the plotter. These devices are used to print large high resolution, vector-based graphics, such as those used in architectural firms. They also prove advantageous as they can draw not only on paper but on varied types of surfaces like plywood, aluminum sheet, plastic, etc. The only drawback is that they are quite expensive and require much larger space than normal printers. Speech Generating Devices The SGDs are augmentative and alternate communication systems used to produce synthesized audio to help people with hearing and speech impairment. The device has a varied language system and is different from the existing audio devices as it can be alternated according to the specific needs of the patient or a child with underdeveloped speech. One can interact with the system by just tilting an eye, tilting the head in different directions, or a finger using the key-guard. The device is one of the major advancements in the field of medical science. One of the great examples of SGD was the one used by the renowned scientist Stephen Hawking. Braille Reader The braille reader or the braille display is a device to assist people with vision impairment. The output produced by the computer is converted into the braille, consisting of small round raised dots on a flat surface, which can be read by the user with the touch of hands.  8. Discuss the following terms: Types of printers, Memory, CD-ROM, Hard disk, Floppy disk. PRINTER:- A printer is an output device that prints paper documents. This includes text documents, images, or a combination of both. The printed output produced by a printer is often called a hardcopy, which is the physical version of an electronic document. While some printers can only print black and white hard copies, most printers today can produce color prints. In fact, many home printers can now produce high-quality photo prints that rival professionally developed photos. TYPES OF PRINTERS There are two kinds of printers: Impact printers Non-impact printers Impact Printers:- Impact printer refers to a class of that work by banging a head or needle against an ink ribbon to make a mark on the paper. This includes: Dot-matrix printers Daisy-wheel printers Line printers Drum printer Dot-Matrix Printers:- The dot-matrix printer uses print heads containing from 9 to 24 pins. These pins produce patterns of dots on the paper to form the individual characters. The 24 pin dot-matrix printer produces more dots that a 9 pin dot-matrix printer, which results in much better quality and clearer characters. The general rule is: the more pins, the clearer the letters on the paper. The pins strike the ribbon individually as the print mechanism moves across the entire print line in both directions, i-e, from left to right, then right to left, and so on. The user can produce a color output with a dot-matrix printer (the user will change the black ribbon with a ribbon that has color stripes). Dotmatrix printers are inexpensive and typically print at speeds of 100-600 characters per second. Daisy-wheel printers:- In order to get the quality of type found on typewriters, a daisy-wheel impact printer can be used. It is called daisywheel printer because the print mechanism looks like a daisy; at the end of each “Petal” is a fully formed character which produces solid-line print. A hammer strikes a “petal” containing a character against the ribbon, and the character prints on the paper. Its speed is slow typically 25-55 characters per second. Line printers:- In business where enormous amount of material are printed, the character-ata-time printers are too slow; therefore, these users need line-at-a-time printers. Line printers, or line-at-a-time printers, use special mechanism thatcan print a whole line at once; they can typically print the range of 1,200 to 6,000 lines per minute. Drum, chain, and band printers are line-at-a-time printers. Drum printer:- A drum printer consists of a solid, cylindrical drum that has raised characters in bands on its surface. The number of print positions across the drum equals the number available on the page. This number typically ranges from 80-132 print positions. The drum rotates at a rapid speed. For each possible print position there is a print hammer located behind the paper. These hammers strike the paper, along the ink ribbon, against the proper character on the drum as it passes. One revolution of the drum is required to print each line. This means that all characters on the line are not printed at exactly the same time, but the time required to print the entire line is fast enough to call them line printers. Typical speeds of drum printers are in the range of 300 to 2000 lines per minute. Non-impact printers Non-impact printers do not use a striking device to produce characters on the paper; and because these printers do not hammer against the paper they are much quieter. Following are some non-impacted printers: Ink jet printers Laser printers Thermal printers Ink-jet printers:- Ink-jet printers work in the same fashion as dot-matrix printers in the form images or characters with little dots. However, the dots are formed by tiny droplets of ink. Ink-jet printers form characters on paper by spraying ink from tiny nozzles through an electrical field that arranges the charged ink particles into characters at the rate of approximately 250 characters per second. The ink is absorbed into the paper and dries instantly. Various colors of ink can also be used. One or more nozzles in the print head emit a steady stream of ink drops. Droplets of ink are electrically charged after leaving the nozzle. The droplets are then guided to the paper by electrically charged deflecting plates [one plate has positive charge (upper plate) and the other has negative charge (lover plate)]. A nozzle for black ink may be all that’s needed to print text, but full-color printing is also possible with the addition of needed to print text, but full-color printing is also possible with the addition three extra nozzles for the cyan, magenta, and yellow primary colors. If a droplet isn’t needed for the character or image being formed, it is recycled back to its input nozzle. Several manufacturers produce color ink-jet printer. Some of these printers come with all their color inks in a cartridge; if you want to replace on color, you must replace all the colors. Other color ink-jet printers allow you to replace ink individually. These printers are a better choice if user uses one color more than other colors. These printers produce less noise and print in better quality with greater speed. Laser printers:- A laser printer works like a photocopy machine. Laser printers produce images on paper by directing a laser beam at a mirror which bounces the beam onto a drum. The drum has a special coating on it to which toner (an ink powder) sticks. Using patterns of small dots, a laser beam conveys information from the computer to a positively charged drum to become neutralized. From all those areas of drum which become neutralized, the toner detaches. As the paper rolls by the drum, the toner is transferred to the paper printing the letters or other graphics on the paper. A hot roller bonds the toner to the paper. Laser printers use buffers that store an entire page at a time. When a whole page is loaded, it will be printed. The speed of laser printers is high and they print quietly without producing much noise. Many home-use laser printers can print eight pages per minute, but faster and print approximately 21,000 lines per minute, or 437 pages per minute if each page contains 48 lines. When high speed laser printers were introduced they were expensive. Developments in the last few years have provided relatively low-cost laser printers for use in small businesses. Advantages of Laser Printer The main advantage of Laser printer is its speed & efficiency at which it prints high-quality quality graphics & text. Laser printers produce high-quality output as compared to other printers. Laser printers are quite and does not produce disturbing sounds. They are also capable to produce color prints. Disadvantages of Laser Printer The main disadvantage of Laser printer is its cost, they are relatively costly as compared to other printers. The maintenance, repair & servicing charges are also high of these printers. Laser printers emit small amount of ozone and are hazardous to health and the atmosphere. Thermal Printer:- A thermal printer is a printer that makes use of heat in order to produce the image on paper. Due to quality of print, speed, and technological advances it has become increasingly popular and is mostly used in airline, banking, entertainment, retail, grocery, and healthcare industries. Thermal printing does not make use of ink or toner unlike many other printing forms but largely depends on thermal papers for producing the images. They are also quiet popular in creating labels owing to speed of printing. Advantages of Thermal Printer No involvement of cartridges or ribbons and thus organizations can save investment by using thermal printers. Easier to use as there are less buttons and use of software involved. Popular in noise-free environments and are great for offices. Largely inexpensive and come in various models and sizes. More efficient and faster in printing monochromic ones compared to other forms of printing. More durable compared to other printers. Disadvantages of Thermal printers: Unlike standard printers, thermal printers usually do not print out colors well. If they become too heated to operate, the ink consumed would be more and the printing may not be precise. Printhead could be harmed by the high heat used while printing, often resulting on cost to repair when it breaks down. Memory What is computer memory? A physical device that stores data or information temporarily or permanently in it is called memory. It’s a device where data is stored and processed. In common, a computer has primary and secondary memories. Auxiliary (secondary) memory stores data and programs for long-term storage or until the time a user wants to keep them in memory, while main memory stores instructions and data during programme execution; hence, any programme or file that is currently running or executing on a computer is stored in primary memory. Memory Classification Computer memory comes in various types and serves different purposes − Primary Memory (RAM - Random Access Memory) − Volatile memory loses its contents when the machine is turned off. RAM stores the data that is actively being used. During the booting process of a system, the operating system actively uses RAM and applications that are necessary to execute a file or a program. It speeds up CPU processing by providing fast data and instruction access. ROM (Read Only Memory) − It stands for Read Only Memory. ROM is a permanent type of memory. ROM information is not lost when power supply is switched off. The Content of ROM is inserted by the computer manufacturer and permanently stored at the time of manufacturing. ROM cannot be overwritten by the computer. It is also called Non- Volatile Memory. Secondary Memory (Storage) − Secondary Memory is also known as permanent memory or non- volatile memory of a computer. Secondary memory retains data when the machine shuts down. Files, programmes, and the OS are stored there permanently. HDDs, SSDs, USB flash drives, and optical discs are non-volatile memory devices. Cache Memory − Memory that is smaller and faster than RAM is called cache memory. It is placed closer to the CPU than the RAM. It saves data and instructions that are used a lot so that processing goes faster. CD-ROM, Hard disk, Floppy disk CD-ROM stands for "compact disc read-only memory," and it refers to a specific kind of compact disc that can store data that can be accessed by a computer. Despite the fact that the compact disc format was initially developed for the purpose of storing and playing back music, it has since been modified to store any kind of binary data. Because virtually any type of data can be stored on CD-ROMs, they are frequently used as a medium for the distribution of computer software, including games and multimedia programs. A hard disc, also known as an HDD (hard disc drive) or hard drive, was formerly known as a fixed disc. It is a type of non-volatile storage device that stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Other common names for hard discs include hard drive and hard disc. The term "hard disc" (sometimes referred to as "platter" or "disc") refers to the storage medium itself, while the term "drive" refers to an entire unit that contains multiple platters, a read/write head assembly, driver electronics, and a motor. The use of hard discs on computers was the original motivation behind their creation. In the 21st century, in addition to computers, hard discs are utilized in digital video recorders, digital audio players, personal digital assistants (PDAs), and digital cameras. A floppy disc is a storage medium that consists of a thin and flexible magnetic disc inside a plastic carrier. A floppy disc drive, also called an FDD or floppy drive, is a device that is used to read information that is stored on data storage media. Floppy discs have a relatively low capacity for data storage. Heat can have an adverse effect on floppies. As a result, they are required to handle with a higher degree of care. Pen Drive When compared to more conventional methods of data storage, pen drives offer superior levels of protection due to their durability and inability to become damaged by scratches. Memory cards These devices are used to store data for specific devices like smartphones and cameras. They typically offer more storage space than comparable flash drives, but they operate in tandem with a host device.