The age in which we are living is the age of science and technology. This is because of the man's discovery and invention of many things for this comport and efficiency. the computer is one of the the most useful inventions of man of this age. in the modern world, computers play the vital role. it has affected almost every part of our life. the word computer is derived from the word compute which means to calculate. so, computer is an electronic machine, which receives input data , processes them and gives meaningful output as a result of processing it even stores a lot of information, which can be processed and analyzed for many purpose. the credit of the invention of computer goes to Charles Babbage. so he is called the father of computer science.on the basis of size computer are of four types : super computer, mainframe computer, mini computer and micro computers. super computer are the largest and fastest computers. They are specially designed for scientific researches and space war. Mainframe computer are very big in size and occupy more space. They have more storing capacity. they work very fast and even provide many facilities. mini computer are large in size and and have a big storing and processing capabilities. these computer are mostly use in connection with more terminals where the workers can work sharing a single computer as file server. Microcomputers are small. they are also called personals computers (PC) or desktop computers. A single user can use these at a time. Even the size has been reduced to laptop and palmtop computers.
computer are used widely because of their speed, accuracy and precision. they are used in industries for calculating income, expenditure and value of products. Complicated calculations can be carried out accurately in a few seconds. They can process information very fast and accurately. so they are widely used in schools, banks, railway platforms, hospitals, post office etc. they have been used in the school for result and calculations. they are used for guidance and control of aircraft and missiles. banks keep their accounts and secrets in computers. reservations for traveling are made by computers. doctors use computers in complicated surgery and analyze the complex structure. the use of Internet has been possible because of computers networks. it has narrow down the entire world. it has enabled to give a lot of information about different aspects from nook and corner of the world. therefore, computers are used in very aspect of human life. They have made human life easier. the use of computer has some drawbacks. it has displaced many people from their work as it does the work of many people. it also creates many health problems to computer workers. computer workers can have problem of eye sight and body paining. it is essential to be aware of the problems created by computers.
to sum up, computers are being used all over the world. because of their speed in working, accuracy diligence, versatility and storage capacity, they have become a part of human life. they have lightened man's burden of work.
PC software
PC Software is a set of instructions grouped into program form that make the electronic devices in the computer to function in the desired way. It is a collection of programs or procedures and associated documentation concerned with the operation of a data processing system. There are generally three types of software: A. System Software B. Programming Software C. Application Software System Software System software is an integrated set of specialized programs that is used to manage the resources and overall operations of a computer. It helps to run the computer hardware and computer system, It includes a combination of the following: - Operating system software It is a program, which controls overall operations (activities) of the computer. It is an interface between hardware and user which is responsible for the management and co-ordination of activities and the sharing of the resources of the computer. DOS, UNIX, Windows 95, 98, ME, Windows XP, Linux etc are the example of operating system. - Utility Software Computer software designed to help manage and tune the computer hardware, operating system or application software by performing a single task or a small range of tasks. Utility software gives services to the computer by providing facilities for performing common tasks such as date transfer, search and merge of files, data and file recovery, diskette management etc. Windows Explorer, Anti-virus utilities, Device Drivers are some examples of it. - Language Processors Language processors are those, which translate the program written in programming language into on executable program (Human understanding language) that is understood and followed by hardware of the computer. Assembler, compiler, interpreter are the examples of language processor. à Assembler: a program, which converts a program, written in low level language into machine code (machine language) à Compiler: a program, which translates a program, written in High level language into binary digits (machine language) is called compiler. à Interpreter: It is different type of translation. It does not convert the programming language into a machine language, but directs the CPU to follow each programming language line by line where as compiler does at a single time whole at a time. Programming Software Programming software usually provides tasks to assist a programmer in writing computer programs, and software using different programming language in a more convenient way. The tools include the following: a. Compilers: a computer program (or set of programs) that transforms source code written in a computer language (the source language) into another computer language (the target language, often having a binary form known as object code). b. Debugger: a debugger is a computer program that is used to test and debug other programs (the "target" program). It is used to find the bugs (errors) and try to solve (debug) it. c. Interpreter: it translates source code into same efficient interpreter representation (code) and immediately executes this. d. Linkers: A program that takes one or more objects generated by executable program. There are basically three levels of programming language. a. Machine level language: In this computer understands only in binary number (binary digits). It is written in machine language only understood by the computer. It is very highly complicated language. b. Low level language: It is machine oriented language. It is similar to machine language but mnemonic codes are used instead of binary digits. Thus it is easier than machine language. It is also called assembly language. c. High level language: These types of language are written in English language with set of rules called syntax. Thus, it is easier to program than the other language. There are easy to write, read and understand. For example, COBOL (COmmon Business Oriented Language), FORTRAN(FORmula TRANslation). BASIC (Beginner's All-purpose Symbolic Intruction Code), C, C++ etc. Application Software The software written for special purpose (specific use) in a specific language is known as Application software. Application software may be defined as software that interfaces between the user and the system software to also the user to perform specific tasks. There are two types of Application Software. a. Packaged Software Package software is also called Pre-written Application Packages. Package software are those that have been written by another person or group and made available to computer users. Ms-Word, Ms-Excel, Ms-PowerPoint, Adobe Page Maker, Freehand, Photoshop, Ms-Access, dbase, auto cade are the examples of Application Software. b. Tailored or Custom Software There software is also called User written Application. These packages are those that are designed and coded by the users who have programming knowledge. These are used to perform the specific, task and fields like Accounting, Super Market Billing, Mark sheet preparation etc which are developed on the demand of clients. ACC, POS2002, MEDI0PRO, TALLY etc are the examples of Tailored software.
Building blocks of computer
1. CPU (Central Processing Unit) 2. Memory 3. Input Devices 4. Output Devices 5. Buses
1. Central Processing Unit (CPU) CPU is known as central engine of the computer. It controls the operation of all the components. It functions as the brain of PC. It's primary function is to execute programs. The CPU fetches one instructions of the program from the memory at a time, decodes it and then executes it. It has further sub parts. a. Arithmetic and Logic Unit (ALU) b. Control Unit (CU) c. Registers (Accumulator and general and special purpose registers. Arithmetic and Logical Unit (ALU) The function of ALU is to perform arithmetic and logic operations. The purpose of the ALU is to perform computation on its data inputs, such as adding the two sets of inputs, or subtracting, or performed by special purpose math processor called floating-point unit (FPU). Control Unit (CU) The control unit of a CPU controls the entire operation of the computer. This very section of the CPU really sets as the brain of the computer. It also controls all other devices such as memory, input and output devices connected to the CPU. Registers A CPU contains a number of registers to store data temporally during the execution of a program. The number of registers differs from processor to processor. Some processors contain more registers some less. Registers are classified as follows - Accumulator: A register which holds one of the operands prior to the execution of an instruction, and received the result of most of the arithmetic and logical operations. - General n Purpose Registers: These registers store data and intermediate results during the execution of a program. - Special Purpose Registers: A CPU contains a number of special purpose registers for different purposes. They are: i. Program Counter (PC) ii. Stack Pointer (SP) iii. Status Register iv. Instruction Register (IR) v. Index Register vi. Memory Address Register (MAR) vii. Memory Buffer Register (MBR) or Data Register (DR) 2. Memory Memory is a storing device, which stores program, data, results and so on. Primary memory is extremely fast in modern computers, and since it interfaces almost directly with the CPU it allows for very fast transfers between the two. Typically, it is in the form of units of memory, which store their data electronically and transfer it to and from the CPU via a fast memory bus which the computer has dedicated to this purpose. ROM is a smaller amount of primary memory which is nonvolatile, but it is really unsuitable for holding anything other than the BIOS (a small program used to load the basic operating system allowing more advanced software, such as Windows or Linux, to be chosen and run). It is optimized and designed for reading from, rather than writing to, although modern ROM chips are capable of having their normally permanent contents changed- a system sometime called PROM (Programmable Read Only Memory) or EPROM (Erasable Programmable Read Only Memory). The cache, which also falls under the category of primary memory, is a nifty feature of most CPUs which makes use of the fact that some parts of RAM are accessed more often than others by storing certain amounts of data in a cache. Instead of retrieving the data from RAM, the CPU retrieves it's from the cache, which is much faster to access since it is located on the CPU itself. It lies between CPU and primary memory whenever data is searched; it is first searched in cache. If not found in cache then it looks in memory and then puts in cache. The defining factor of primary memory is that it is a permanent feature of the computer system itself, and not a removable or interchangeable part. However, since the hard drive of modern computers is just as interchangeable as the RAM and ROM chips, this distinction is often somewhat blurred. Secondary memory is designed to overcome some of the limitation of primary memory. It is non-volatile; meaning that it retains system is switched off. This allows it to retain its data on along-term basis, while primary memory can not. Given its relatively high capacity compared to primary memory of the same price, it is for more feasible for use as a mass storage device. As important aspect of secondary memory is that it can not be addressed directly by the CPU, while a variable in memory can point to other locations in memory, it's not possible to "point" to a location in secondary memory. This is a major distinction between primary and secondary memory. It means that a computer system is unable to point to a location in memory, even if it wanted to secondary memory can not be used as primary memory. However, the CPU can be used to transfer data from the secondary memory into primary memory, and the data can be accessed from there. 3. Bus Bus is an electronic road along which signals are sent from one part of the computer to another. It's a group of lines or wires connecting memory or I/O devices. It carries data, address, control signals and power from one place to another on the motherboard. Bus is divided into three types: a. Address Bus Address bus carries the address of memory location or I/O device that the CPU wants to access. b. Data Bus Data bus used to move data from one place to another. The number of the data lines provided in the bus is very important factor that determines the speed of this data transfer. This bus is bidirectional. c. Control Bus Control bus is used to sent control and timing signals between various parts of the computer. It is also bidirectional. 4. Input Devices Input devices take the data to help them convert into suitable binary form acceptable to the computer. For example: keyboard, mouse, scanner, joystick, light pen, camera, microphone, BCR, OCR, OMR etc. 5. Output Devices Output devices receive result or processed data and provide them to users. The computer sends information to an output device in the binary form. For example: monitors, printer, speakers, plotters etc.
1. Central Processing Unit (CPU) CPU is known as central engine of the computer. It controls the operation of all the components. It functions as the brain of PC. It's primary function is to execute programs. The CPU fetches one instructions of the program from the memory at a time, decodes it and then executes it. It has further sub parts. a. Arithmetic and Logic Unit (ALU) b. Control Unit (CU) c. Registers (Accumulator and general and special purpose registers. Arithmetic and Logical Unit (ALU) The function of ALU is to perform arithmetic and logic operations. The purpose of the ALU is to perform computation on its data inputs, such as adding the two sets of inputs, or subtracting, or performed by special purpose math processor called floating-point unit (FPU). Control Unit (CU) The control unit of a CPU controls the entire operation of the computer. This very section of the CPU really sets as the brain of the computer. It also controls all other devices such as memory, input and output devices connected to the CPU. Registers A CPU contains a number of registers to store data temporally during the execution of a program. The number of registers differs from processor to processor. Some processors contain more registers some less. Registers are classified as follows - Accumulator: A register which holds one of the operands prior to the execution of an instruction, and received the result of most of the arithmetic and logical operations. - General n Purpose Registers: These registers store data and intermediate results during the execution of a program. - Special Purpose Registers: A CPU contains a number of special purpose registers for different purposes. They are: i. Program Counter (PC) ii. Stack Pointer (SP) iii. Status Register iv. Instruction Register (IR) v. Index Register vi. Memory Address Register (MAR) vii. Memory Buffer Register (MBR) or Data Register (DR) 2. Memory Memory is a storing device, which stores program, data, results and so on. Primary memory is extremely fast in modern computers, and since it interfaces almost directly with the CPU it allows for very fast transfers between the two. Typically, it is in the form of units of memory, which store their data electronically and transfer it to and from the CPU via a fast memory bus which the computer has dedicated to this purpose. ROM is a smaller amount of primary memory which is nonvolatile, but it is really unsuitable for holding anything other than the BIOS (a small program used to load the basic operating system allowing more advanced software, such as Windows or Linux, to be chosen and run). It is optimized and designed for reading from, rather than writing to, although modern ROM chips are capable of having their normally permanent contents changed- a system sometime called PROM (Programmable Read Only Memory) or EPROM (Erasable Programmable Read Only Memory). The cache, which also falls under the category of primary memory, is a nifty feature of most CPUs which makes use of the fact that some parts of RAM are accessed more often than others by storing certain amounts of data in a cache. Instead of retrieving the data from RAM, the CPU retrieves it's from the cache, which is much faster to access since it is located on the CPU itself. It lies between CPU and primary memory whenever data is searched; it is first searched in cache. If not found in cache then it looks in memory and then puts in cache. The defining factor of primary memory is that it is a permanent feature of the computer system itself, and not a removable or interchangeable part. However, since the hard drive of modern computers is just as interchangeable as the RAM and ROM chips, this distinction is often somewhat blurred. Secondary memory is designed to overcome some of the limitation of primary memory. It is non-volatile; meaning that it retains system is switched off. This allows it to retain its data on along-term basis, while primary memory can not. Given its relatively high capacity compared to primary memory of the same price, it is for more feasible for use as a mass storage device. As important aspect of secondary memory is that it can not be addressed directly by the CPU, while a variable in memory can point to other locations in memory, it's not possible to "point" to a location in secondary memory. This is a major distinction between primary and secondary memory. It means that a computer system is unable to point to a location in memory, even if it wanted to secondary memory can not be used as primary memory. However, the CPU can be used to transfer data from the secondary memory into primary memory, and the data can be accessed from there. 3. Bus Bus is an electronic road along which signals are sent from one part of the computer to another. It's a group of lines or wires connecting memory or I/O devices. It carries data, address, control signals and power from one place to another on the motherboard. Bus is divided into three types: a. Address Bus Address bus carries the address of memory location or I/O device that the CPU wants to access. b. Data Bus Data bus used to move data from one place to another. The number of the data lines provided in the bus is very important factor that determines the speed of this data transfer. This bus is bidirectional. c. Control Bus Control bus is used to sent control and timing signals between various parts of the computer. It is also bidirectional. 4. Input Devices Input devices take the data to help them convert into suitable binary form acceptable to the computer. For example: keyboard, mouse, scanner, joystick, light pen, camera, microphone, BCR, OCR, OMR etc. 5. Output Devices Output devices receive result or processed data and provide them to users. The computer sends information to an output device in the binary form. For example: monitors, printer, speakers, plotters etc.
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