Computer overview A bhishek Sharma Class-IX B

1. Computer overviewAbhishek Sharma Class-IX B

2. COMPUTER A computer is an electronic device that can performs variety of operations in accordance with set of instructions called program. Data: Dataare raw facts and figures. Data processing system transforms data into useful information. Information: It means what we get after processing data (meaningful data).Data are aggregated And summarized in various meaning ways to form information. Components of computer Input unit: A n input unit takes the input and converts it into binary form so that it can be understand by the computer. Central processing unit(CPU): The CPU is the control centre for a computer .it guides, directs and governs its performances. It is the brain of the computer. The CPU has two components which are responsible for different functions. CPU has two components ALU and CU. (I)ALU-It performs all arithmetic and logical operation of the computer. (ii)CU-It controls all the work performs by the ALU. of CPU.

3. Basic structure of computer ALU Input unit Output unit CU Secondary storage Main memory

4. Output unit:  It takes the processed data from the PU in the form of electrical signals. It converts these signals into user understandable language. Memory: The memory of computer is often called main memory or primary memory. It is generally the third component . Memory cell: A memory cell may be defined as a device which can store a symbol selected from a set of symbols. 8bits=1kb, 1nibble=4bits, 1024kb=1MB,1024MB=1GB,1024GB=MG,1024GB=1TB A group of 8 bits is called a byte and a group of 4 bits is called a nibble Live ware. It is the term generally used for the people associated with and benefited from the computer system.

5. Hardware: Hardware represents the physical and tangible components of the computer. The components that can be see and touch. Peripherals: The peripherals are the devices that surround the system unit e.g. the keyboard, mouse, speaker, printer, monitor etc. are peripherals. • Software: Software represents the set of programs that governs the operation computer system • and make the hardware run. Software can be classified broadly into three categories: • i)Operating software: An Operating system is a program which acts as an interface between • a user and the hardware (i.e. all computer resources • (ii)Language processors: It performs the operation of language conversion between user and • the Computer. It converts binary language into machine level language and assembly language • into high level language. • (iii)Application software: Application software is the set of programs necessary to carry out • Operations for specified applications. • Firmware: • Like hardware and software, firmware is another term commonly used. • Firmware is a prewritten program that is permanently stored in read-only memory. • It configures the computer and is not easily modifiable by the user. • BIOS instructions are an example of firmware. Hardware and software

6. Software: Software represents the set of programs that governs the operation computer system and make the hardware run. Software can be classified broadly into three categories: (i)Operating software: An Operating system is a program which acts as an interface between a user and the hardware (i.e. all computer resources (ii)Language processors: It performs the operation of language conversion between user and the Computer. It converts binary language into machine level language and assembly language into high level language. The processors are given below: Assembler: This language processor converts he program written in assembly language into machine level Language. Interpreter: This language processor converts a HLL program into machine language by converting and executing it line by line. If error occurs, it reports it at the same time and program execution cannot resume until the error is rectified. Compiler: It also converts the HLL program into machine language program but the conversion Manner is different .I converts he entre HLL program in one go and report all the errors of the program along with the line Software

7. Application software Application software: Application software is the set of programs necessary to carry out operations for specified applications. It is also of two types Customized Application software: this type of software is tailor-made software according to a user’s requirement. The software is developed to meet all the requirements specified by the user. However, this cannot be directly installed at any other user’s workplace as the requirement of this user may differ from the first one and the software may not fit in the requirement of the new user. General application software: This type of software is developed keeping in mind the general requirement for carrying out a specific task. Many users can use it simultaneously as it fulfils the general requirement.

8. Language processor Language processors: It performs the operation of language conversion between user and the Computer. It converts binary language into machine level language and assembly language into high level language. The processors are given below: Assembler: This language processor converts he program written in assembly language int machine Language. Interpreter: This language processor converts a HLL program into machine language by converting and executing it line by line. If error occurs, it reports it at the same time and program execution cannot resume until the error is rectified. Compiler: It also converts the HLL program into machine language program but the conversion Manner is different .I converts he entre HLL program in one go and report all the errors of the program along with the line

9. Speed: Computer is much faster as compared to human being. A computer can perform a task in a minute that may take days if performed manually. A modern computer cans execute millions of instructions in one second. High storage capacity: Computer can store a large amount of information in very small space. A CDROMof 4.7 inch diameter can store all the 33 volumes of encyclopedia Britannica and will still have room to store more information. Bubble memories can store 6, 250, 00 bits per square centimeter of space. Accuracy: Computer can performs all the calculations and comparisons accurately provided the hardware does not malfunction. Reliability: computers are immune to tiredness and boredom or fatigue. Thus they are more reliable than human beings. Versatility: Computer can perform repetitive jobs efficiently. The can solve labor problem or do hazardous jobs in hostile environment. They even can work in the areas where human brain can err of instance observing motion of very fast moving articles. Also they can work with different types of data and information like graphic, audio, visual, characters etc. Strengths of computer

10. Lack of decision making power: computer cannot decide on their on own. They do not possess thispower which is a great asset of human beings. IQ zero: Computer are dumb machines with zero IQ. They need to be told each and every step, however minute it may be. These limitations of computer are characteristics of human beings. Thus, computer and human being work in collaboration to make to make a perfect pair. weaknesses

11. (1)The first generation computers (1949-55) the first generation computers used thermionic • values (vacuum tube) and machine language was used • for giving instruction. First generation computers used the concept of stored program. • The computers of this generation were very large in size and their • programming was a difficult task. There are four type of computers of this generation are a) ENIAC b) EDVAC c) EDSAC d) UNIVAC-1 • 2) The second generation computers (1956-65) a big revolution in electronics took place with the • invention of transistors by Bardeen, Brattain and Shockley in 1946. • They occupied less space and required only 1/10 of the power required by tubes. • The second generation computers began with the advent of transistorized circuitry, • invention of magnetic core and development of magnetic disk storage devices. • This new development made these computers much more reliable. The increased • reliability and availability of large memories paved the way for the development of • high level language (HLL) such as FORTRAN, COBOL, Algal and Snob etc. With speedy CPUs • and the advent of magnetic tape and disk storage, operating systems came into being. Batch • operating systems ruled the second generation computers. Evolution of computer The founder of computer is Charles Babbage

12. (3)The third generation computers (1966-75) the generation computers replaced transistors with “Integrated Circuits” know popularly as chips. The “Integrated Circuit “or I.C. was inverted by Jack Kirby at Texas Instruments in 1958. An I.C.is wafer thin slice of extremely purified silicon crystals. The third generation computers using integrated circuits proved to be highly reliable, relatively Inexpensive, and faster. Computers these days found place in other areas also like education, survey, small businesses, estimation, analysis etc. along with their previous usage areas i.e. , scientific and engineering. (4)The fourth generation computers (1976-Present) the advent of the microprocessor chip marked the beginning of the fourth generation computers. Medium scale integrated (MSI) circuits yielded to Large and Very Large Scale integrated (MSI) circuits yielded to large and very large scale integrated (VLSI) circuit packing about 50000 transistors in a chip. Different type of secondary memory with high storage capacity and fast access developed. (5)The fifth generation computers(coming generation) it is based on artificial intelligence, are still in development, though there are computers will have to be able to classify information, search large databases rapidly plan, apply the rules which humans regard as clear thinking.

13. Computer Digital------- --Analog------------Hybrid Purpose-wise ---------------size and performance wise Embedded ----micro-------mini------mainframes ---super Programmable -------laptop-------------workstations

14. Digital computer: A computer that deals with discrete quantities. It counts rather than measuring. It can also be divided into two parts which are given below as: I) Purpose-wise: It is of two types Special-purpose:Special-purpose computer is one that is designed to perform a specific Task. The instructions (programs) to carry out the task are permanently stored in the machine For the specific task, this type of computer works efficiently but such computers are not versatile. General-purpose computer. General-purpose computers is one that can work on different types Of program input to it and thus be used in countless application .The program are not Permanently stored but are input at the time of execution. These computers are versatile. Performance wise: Performance wise it is divided into five parts which are given below 1. Embedded computers: computers exits in a wide range of sizes and power. The smallest are Embedded within the circuitry of appliances, such as televisions, washing machine and wrist Watches. These computer are typically preprogrammed for a specific task, such as tuning to Particular television frequency or keeping accurate time.

15. 2. Microcomputers: A microcomputers is a computer whose CPU is a microprocessor. A microprocessor is a processor whose all components are a single integrated-circuit chip. Those Is normally single-microprocessor, single-user system designed for performing basic OperationsLike educational, training, small business application, playing games etc. these are mainly usesOffices, homes, schools, stores, shops etc. IBN PCs, APPLE Machine PS/2 are some popular Computers of this range. Three major categories at microcomputers: (i)PDAs (ii)Desktop computer (Iii)workstations (i)Programmable computer or PDAs. Programmable computers vary enormously in their Computational power, speed, memory, and physical size. The smallest of these computers can be held in one hand and are called personal digital assistant(PDAs).They are used as Notepads, Scheduling system, and called address books; if equipped with a cellular phone, they can connect To worldwide computer networks to exchange information regardless of location. (ii)Laptop (network) computer and desktop personal computers (PCs). Laptop computers and Desktop PCs are typically used in businesses and at home to communicate on computer networks, For word processing to track finances and to play games. They have large amounts of internal Memory to store hundreds of programs and documents. They are equipped with a keyboard: a Mouse, track ball are other pointing devices; and a video display monitor or liquid crystal display (LCD) to display information. Laptop computers usually have similar hardware and software as PCs, But they are more compact and have flat, lightweight LCDs instead of video display monitors. Laptop computers are so computers are as called as they can sit on a Lap and Desktop computers Are So called as they can sit on a desk.

16. (iii) Workstations. Workstations are similar to personal computers but have greater memory and More extensive mathematical abilities and they are connected to other workstations or personalComputer to exchange data. They are typically found in scientific, industrial and businessEnvironments that require high levels of computational abilities. • 3. Minicomputers. Also called mid-range services are more powerful computers than micro-computer In terms of processing power and capabilities. Minicomputers are mainly multiuser system where Many Users simultaneously work on the system. Mini computers process greater storage capacity and Larger memories as compared to microcomputer. These are even capable of handling more input-output devices .ex is: PDP-11, VAX, 77500 MAGNUM ETC. • 4. Mainframe computers are designed to handle huge volumes of data and information. These Support more than hundred users at same time. These very large and expensive computers have Great processing speeds and very large storage capacity and memory as compared to Minicomputers. These computers even possess and with more than one processor at the same time • .Thus one can say these are multiuser, multiprocessor system. for mainframe computer very sophisticated operating system are needed to control and supervise their operation. Examples are: ICL 39, CDC 6600, VAX 8842, IBM 3090/600, and IBM4381. • 5.Super computers are the most powerful computers among digital computers. These consist of several processors running together thereby making them immensely faster and powerful. These

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