COMPUTER KNOWLEDGE -INTRODUCTION • A Computer is a general purpose device that can be programmed to carry out a set of arithmetic or logical operations automatically. Since a sequence of operations can be readily changed, the computer can solve more than one kind of problem. • A general purpose computer has four main components: the arithmetic logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). • The data that is fed into a computer processor received into the computer by a keyboard or other sources is called Input. • A computer is an electronic device that accepts data from the user (input), processes the data by performing calculations and operations on it and generates the desired Output. • The device which is used with a computer to display or store data is called Peripherals. • The mechanical, magnetic, electronic and electrical components that comprises a computer system such as the Central Processing Unit (CPU), monitor, keyboard, etc. is known as Hardware. • A set of instructions that tells the computer about the tasks to be performed and how these tasks are to performed, is known as Software. • An unprocessed collection or representation of raw facts represented in a manner suitable for communication, interpretation or processing by humans or by automatic means, is known as Data. • The result of processing, manipulating and organising data in a way that adds to the knowledge of the person receiving it, is known as Information. • The smallest unit of information, a computer can understand and process, is known as Bit. • The primary goal of computer is to process information that it receives and output the results. The process of control and alter information is known as. Processing. • Which number system computer used to store data and perform calculation? Binary Number System. • Computer Speed, Accuracy, Diligence, Storage Capability, Automation, Remembrance Power and Versatility are the main Characteristics of Computer. • Self Intelligence, Decision-Making power, Learning power, Self care, Fellings are the Limitations of Computer. • A mainframe computer is a much larger computer that typically fills a room and may cost many hundreds or thousands of times as much as a personal computer. They are designed to perform large numbers of calculations for governments and large enterprises. • Read-only memory (ROM) is a storage medium used in computers and other electronic devices. Data stored in ROM can only be modified slowly or with difficulty, or not at all. ROM is non-volatile and the contents are retained even after the power is switched off. It only allows reading. The types of ROM include PROM, EPROM and EEPROM. • Random Access Memory (RAM), allows the computer to store data for immediate for immediate manipulation and to keep track of what is currently being processed. RAM is referred to as volatile memory and is lost when the power is turned off. It allows reading and writing. The two main types of RAM are static RAM and dynamic RAM. • SRAM retains data as long as power is provided to the memory chip and need not be refreshed periodically. SRAM stands for Static Random Access Memory. • The data on DRAM continues to move in and out of the memory as long as power is available and must be continually refreshed to maintain the data. DRAM stands for Dynamic Random Access Memory. • Primary memory is computer memory that a processor or computer accesses first or directly. For example: RAM, and Cache Memory. • Secondary memory (or secondary storage) is the slowest and cheapest form of memory. It cannot be processed directly by the CPU. Secondary memory devices include magnetic disks like hard drives and floppy disks, optical disks such as CDs and CDROMs, and magnetic tapes, which were the first forms of secondary memory. • Virtual memory is memory on the hard disk that the CPU uses as an extended RAM. • Installation is the process of copying software programs from secondary storage media to the hard disk. • A central computer that holds collections of data and programs for many PCs, workstations and other computers is a Server. GENERATIONS OF COMPUTER • Which was the first general purpose computer, designed to handle both numeric and textual information? Universal Automatic Computer (UNIVAC) (1951) • First Generation (1940-1956) Vacuum Tubes: The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. The UNIVAC and ENIAC computers are examples of first-generation computing devices. In first generation of computer, this operating system allowed only one program to run at a time and a number of input jobs are grouped for processing. It is known as Batch Processing. • Second Generation (1956-1963) Transistors: Transistors replaced vacuum tubes and ushered in the second generation of computers. • Third Generation (1964-1971) Integrated Circuits: The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers. • Fourth Generation (1971-Present) Microprocessors: The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand Fourth generation computers also saw the development of GUIs, the mouse and handheld devices • Fifth Generation (Present and Beyond) Artificial Intelligence: Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. • In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. COMPUTER ORGANISATION • An Arithmetic Logic Unit (ALU) is a digital circuit that performs integer arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer. • Control Unit is responsible for controlling the overall operations of computer. It coordinates the sequence of execution of instructions and controls the overall functioning of the computer. • The first computer architecture was introduced by John Von Neumann (1970) • Personal computers use a number of chips mounted on a main circuit board called Motherboard. • The CPU is fabricated as a single Integrated Circuit (IC) chip. It is also known as the Microprocessor. • Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor and/or the ability to allocate tasks between them. • The organisation and interconnection of the various components of a computer system is known as Computer Architecture. • A CPU can directly understand the Machine Language. INPUT & OUTPUT DEVICES • An input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to a computer. They are the devices that feed data into a computer. Examples of input devices include keyboards, mouse, scanners, digital cameras and joysticks. • The keys include the letter keys (0, 1, 2, ..., 9; A, B, Z), which are generally laid out in the same style as in typewriters are known as Alphanumeric Keys. • Caps lock and Num lock keys are called as Toggle Keys because when pressed, they change their status from one state to another. • Numeric Keypad is a keypad located on the right hand side of the keyboard. It consists of digits and mathematical operators. • A Modifier key is a special key (or combination) on a computer keyboard that temporarily modifies the normal action of another key when pressed together. By themselves, modifier keys usually do nothing; that is, pressing any of the Shift, Alt, or Ctrl keys alone does not (generally) trigger any action from the computer. • A Mouse is the most popular input device which is used today for interactive processing and for the one line entry of data for batch processing. Drag and Drop refers to the action of clicking and holding down the mouse button, while moving the mouse and then releasing the mouse button. The first computer mouse was invented by Douglas Engelbart. • Joystick is the device that moves in all directions and controls the movement of a pointer. • A Touch Screen is a type of display screen device that is placed on the computer monitor to allow direct selection or activation of the computer when the user touches the screen. • Light Pen is the pen shaped device, which can sense light and is used to point at spots on a video screen. • A technology enables a high-speed reading of large quantities of data and transferring these data to the computer without using a keyboard. It is referred as Optical Mark Reader (OMR). It uses a beam of light that is reflected on the paper with marks, to capture presence and absence of marks. • MICR reads the characters by examining their shapes in a matrix form and the information is then passed on to the computer. MICR stands for Magnetic Ink Character Reader. It provides a high level of security and is therefore used by the banking industry for faster processing of the cheques • It is a machine readable code, which is represented by parallel vertical lines with varying widths. For reading these bar-coded data, a device is used, which is known as a Bar Code Reader (BCR) • Optical Character Recognition (OCR) is used to scan the document containing text. It is the mechanical or electronic conversion of scanned or photographed images of typewritten or printed text into machine-encoded/computer-readable text. • A keyboard is a typewriter-style device, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. Most of the commonly available personal computers have a keyboard, popularly known as Qwerty. • The keys labelled Fl to F12 on the keyboard are called Function Keys. • An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) which converts the electronically generated information into human-readable form • The printed form of output is referred as Hard Copy. • The form of output displayed on the screen is referred as Soft Copy. • The device that prints information from the computer onto the paper is Printer. • Pages Per Minute (PPM) is the unit used to count the speed of the printer. • On the basis of technology, printers are categorised into Impact and Non- Impact Printers. • Impact printers create an image by using some mechanism to physically press an inked ribbon against the page, causing the ink to be deposited on the page in the shape desired. Examples of Impact Printers are Character Printers and Dot Matrix Printers. • Non – Impact Printers do not touch the paper when creating an image. Examples of Non - Impact Printers are Inkjet printers, Laser printers, Solid ink printers, Dye-sublimation, Thermal wax printers, Thermal autochrome printers. • A pen based output device, attached to a computer for making vector graphics, that is, images created by a series of many straight lines is known as Plotters. • The number of pixels displayed on a screen is known as Resolution. • A Monitor is a TV-like display attached to the computer on which the output can be displayed and viewed. It can either be a monochrome display or a colour display. HARDWARE AND SOFTWARE BASICS • The set of instructions, which control the sequence of operations, are known as Program. It is a sequence of instructions, written to perform a specified task with a computer. • A Software instructs the computer what to do and how to do it. It is a set of instructions that tells the computer about the tasks to be performed and how these tasks are to performed. • One or more defects or problems that prevent the software from working as intended of working at all is a Bug. • Software that contributes to the control and performance of the computer system and permits the user to use the system more conveniently is termed as System Software. • Antivirus Software is used to scan the hard disk to remove the virus from them. • The assembly language program is translated into machine code by a separate program known as an Assembler. • A Backup, or the process of backing up, refers to the copying and archiving of computer data so it may be used to restore the original after a data loss event. It contains a copy of every program data and system file on a computer. • An Operating System controls the way in which the computer system functions and provides a means by which users can interact with the computer. • Loading of the Operating System is known as Booting. Restarting a computer that is already on, is referred to as Warm Booting. • Basic Input – Output System (BIOS) is the part of operating system that manages the essential peripherals such as the keyboard, screen, disk drives and parallel and serial ports. • An Integrated Software is a single application that combines major features of several types of application. • An Application Software is the program that makes the computer useful to the users. • Computer hardware is the collection of physical elements that constitutes a computer system. • Computer hardware refers to the physical parts or components of a computer such as the monitor, mouse, keyboard, computer data storage, hard drive disk (HDD), system unit (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that can be touched. • The motherboard is the main component of computer. It is a large rectangular board with integrated circuitry that connects the other parts of the computer including the CPU, the RAM, the disk drives(CD, DVD, hard disk, or any others) as well as any peripherals connected via the ports or the expansion slots. • Here are some common individual computer hardware components that youll often find inside a modern computer case: Motherboard Central Processing Unit (CPU) Random Access Memory (RAM) Power Supply Video Card Hard Drive (HDD) Solid-State Drive (SSD) Optical Drive (e.g. BD/DVD/CD drive) Card Reader (SD/SDHC, CF, etc.) • Here are some common hardware that you might find connected to the outside of a computer: Monitor Keyboard Mouse Battery Backup (UPS) Printer Speakers • Here are some less common computer hardware, (either because these pieces are now usually integrated into other devices or because theyve been replaced with newer technology): Sound Card Network Interface Card (NIC) Expansion Card (Firewire, USB, Thunderbolt, etc.) Hard Drive Controller Card Analog Modem Scanner Floppy Disk Drive Joystick Webcam Microphone Tape Drive Zip Drive • The following hardwares are referred to as network hardware and various pieces are often part of a home or business network: Digital Modem (e.g. Cable Modem, DSL Modem, etc.) Router Network Switch Access Point Repeater Bridge Print Server Firewall INTERNET • The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to link several billion devices worldwide. • It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless, and optical networking technologies. • The World Wide Web (abbreviated as WWW or W3, commonly known as the Web) is a system of interlinked hypertext documents that are accessed via the Internet. • A Website, is a set of related web pages served from a single web domain. • A Home page, index page, or main page is a page on a website. A home page usually refers to: The initial or main web page of a website, sometimes called the front page (by analogy with newspapers). The first page that appears upon opening a web browser program, which is also sometimes called the start page. This start page can be a website or it can be a page with various browser functions such as the visual display of websites that are often visited in the web browser. The web page or local file that automatically loads when a web browser starts or when the browsers home button is pressed; this is also called a home page. The user can specify the URL of the page to be loaded, or alternatively choose e.g. to re-load the most recent web page browsed. A personal web page, for example at a web hosting service or a university web site, that typically is stored in the home directory of the user. • A Hyperlink is a reference to data that the reader can directly follow either by clicking or by hovering or that is followed automatically • A web browser (commonly referred to as a browser) is a software application for retrieving, presenting and traversing information resources on the World Wide Web. • The Uniform Resource Locator, abbreviated as URL is a specific character string that constitutes a reference to a resource. In most web browsers, the URL of a web page is displayed on top inside an address bar. An example of a typical URL would be • Downloading means to receive data to a local system from a remote system, or to initiate such a data transfer • Uploading refers to the sending of data from a local system to a remote system such as a server or another client with the intent that the remote system should store a copy of the data being transferred • An Internet Protocol address (also known as an IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network. It acts as an identifier for a computer. It is a unique address for every computer. • An email attachment is a computer file sent along with an email message. One or more files can be attached to any email message, and be sent along with it to the recipient. • Hotmail was co - founded by an Indian American entrepreneur Sabeer Bhatia along with Jack Smith in July of 1996 • CC (Carbon Copy) in Email indicates those who are to receive a copy of a message addressed primarily to another. The list of CCed recipients is visible to all other recipients of the message. • An additional BCC (blind carbon copy) field is available for hidden notification; recipients listed in the BCC field receive a copy of the message, but are not shown on any other recipients copy (including other BCC recipients) • The Drafts folder retains copies of messages that you have started but are not yet ready to send. • The first email was sent by Ray Tomlinson to himself in 1971. Domain Types Type Description Com Commercial and for profit organizations Edu Education Provider, college, Universities Gov Federal Government Agencies Mil US military sites Net Internet infrastructure and service providers Org Miscellaneous and non-profit organizations
Posted on: Sat, 25 Oct 2014 17:33:11 +0000
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