Introduction-to-Computer-2 (1).pdf

Introduction to Computer DATA PROCESSING DATA  A collection of unorganized facts or figures gathered from one or more sources Types of Data Numeric Alphabetic Alphanumeric DATA PROCESSING  the TRANSFORMATION of raw data into useful informati...

Introduction to Computer DATA PROCESSING DATA  A collection of unorganized facts or figures gathered from one or more sources Types of Data Numeric Alphabetic Alphanumeric DATA PROCESSING  the TRANSFORMATION of raw data into useful information  The manipulation of data into a more useful form  A system wherein data are manipulated to create the desired information which will be used by man in planning and decision making INFORMATION  Consists of data that have been organized and made meaningful to the person or persons receiving it. TYPES OF DATA PROCESSING  Manual System - All operations from data gathering to output preparations are performed by man without the aid of any single machine  Mechanical / key-driven System - Bulk of work are performed by man with some assistance from machines (e.g.: typewriter, calculator, adding machines, etc.)  Electronic Data Processing - Majority of operation makes use of computers to get the required output. DATA PROCESSING CYCLE ORIGINATION  ORIGINATION – the process of collecting the original or initial data; a SOURCE DOCUMENT (the original recording of data) is created INPUT  INPUT - the preparation of initial data for processing  PROCESS – changing of data usually combining with other data to PROCESS STORAGE produce information  STORAGE – keeping the processed data for future use or for OUTPUT further processing  OUTPUT – the generated results of the preceding steps DISTRIBUTION  DISTRIBUTION – the giving away of the output data to interested parties; a REPORT DOCUMENT (recording of output data) is generated METHODS OF DATA PROCESSING  BATCH PROCESSING - a technique in which data are to be processed or programs to be executed are collected into groups over a period of time and processed periodically  ONLINE / REALTIME DATA PROCESSING - data is processed immediately after a transaction occurs DATA PROCESSING OPERATIONS  Classifying - identifying and arranging items with like characteristics into groups or classes  Sorting - arranging or re-arranging data in a pre-determined sequence to facilitate processing  Calculating - arithmetic manipulation of the data  Summarizing - condensing or shifting data so that the resulting output reports will be concise and effective  Communicating - printing the information in a usable form and communicating it to the user  Storing - placing similar data into files for future reference  Retrieving - recovering stored data and/or information when needed  Reproducing - copying or duplicating data Introduction to Computer Page 1 PROPERTIES OF INFORMATION  Accuracy – ratio of correct information to the total amount of information produced over a period of time  Timeliness – immediate response time of the information system such that information has not lost its freshness and value  Conciseness – extent of getting or extracting those items of information that are needed  Completeness – integrating of facts available at scattered points to suit the needs of the user  Relevancy - property of information that meets the needs of the user at a certain period of time IMPROVEMENT IN COMPUTER PROCESSING  Difficulties in handling increased workloads o the growth in size, complexity and multinational scope of the firm o the increased requirements for data from external sources o the demands of managers for more kind of information  Failures to supply accurate information  Failures to supply timely information  Increases on costs ADVANTAGES OF ELECTRONIC DATA PROCESSING  Speed of Operation - operation is done by the speed of electric flow in billionths or trillionths of a second  Accuracy - when operations are programmed correctly, the results are highly accurate  Automatic Operation - it carries out operation without human intervention  Decision Making Capability - it can determine whether a certain statement is true or false. It can choose one or the other course of action out of the alternatives in the computer program  Compact Storage - ability to store large amount of data in a compact and easily retrievable form  Discipline it imposes - understanding to the depth of detail and insight in needed in making the program for the computer What is a COMPUTER?  a general-purpose digital electronic device that aids or helps man in data processing o GENERAL PURPOSE - it can be programmed to perform a wide variety of applications o DIGITAL means that computer handles all data internally in the form of numbers (all of the numeric data, all of the text data, and even sounds and pictures are stored as numbers) o ELECTRONIC - manipulate data using electronic switching circuits to perform calculations)  is a device that performs four functions:  it inputs data (getting information into the machine);  it stores data (holding the information before and after processing);  it process data (performing prescribed mathematical and logical operations on the information at high speed); and  it outputs data (sending the results out to the user via some display method). A computer system is consists of  hardware - refers to the physical components of a computer. These are the parts and peripherals connected that you can see, feel and hear. Peripherals are any devices attached to the computer for purposes of input, output, and storage of data (such as a keyboard, monitor display, or external hard disk).  software refers to the programs that control the computer and make it function and associated data (information) stored in the computer Program a set of instructions that the computer obeys. Computer programs can be extremely long and complex sets of instructions. It is quite common for computer programs to be tens of thousands of lines long. The application programs that you use on your PC for word processing and spreadsheets are in fact even longer Introduction to Computer Page 2 As a user…  you interact with the programs running on your computer through the input devices connected to it, such as a mouse and a keyboard  you use these devices to provide input (such as the text of a report you are working on) and also to give commands to the program (such as specifying what text is to appear with bold formatting)  The computer program will provide output (the data resulting from the manipulations within the computer) via various output devices for presenting the information (such as a monitor, a printer, or a sound output system that beeps if the program needs your attention) INPUT DEVICES - are machines or physical equipments that feed data into the CPU of the computer OUTPUT DEVICES - are machines or physical equipments that write (store) data into secondary storage or into output media readable by humans COMPUTER CHARACTERISTICS COMPUTER CAPABILITIES  It is a machine.  It can perform mathematical and logical operations  It is electronic.  It can process data at a very fast speed with almost perfect  It is automatic accuracy  It can store and recall information  It can store a great amount and variety of information  It can handle volumes of repetitive tasks accurately over long periods of time  It can communicate with its operators and other machines COMPUTER LIMITATIONS  It can only carry out those operations that a person has programmed or instructed it to perform.  It can detect, but generally cannot correct, a wrong instruction by itself  It is subject to occasional breakdown or malfunction HISTORY OF COMPUTERS Abacus  The Chinese abacus was developed about 5000 years ago.  Abacus is a mechanical device for making calculations consisting of a frame mounted with rods along which beads or balls are moved  The abacus was so successful that its use spread from China to many other countries. Napier's Logs and Bones  John Napier developed the idea of logarithm.  He used ‘logs’ to transform multiplication problems to addition problems.  Napier’s logs later became the basis for a well known invention-computer machine known as ‘slide rule’.  Napier also derived set of numbering rods known as Napier's bones. Pascal's Adding Machine  Blaise Pascal invented a machine in 1642 made up of gears which was used for adding numbers quickly.  The machine was capable of adding and subtracting.  It worked on clock time mechanism principle Leibnitz's calculator  Gottfried Leibnitz improved an adding machine and constructed a new machine in 1671.  The machine was capable to perform multiplication and division as well. Jacquard's Loom  In 1801, Joseph Marie Jacquard invented an improved textile loom.  The Jacquard loom was the first machine to use punched card. These punched cards controlled the weaving, enabling an ordinary workman to produce the most beautiful patterns in a style previously accomplished only with patience, skill, and hard work.  Jacquard's loom mechanism is controlled by recorded patterns of holes in a string of cards, and allows, what is now known as, the Jacquard weaving of intricate patterns. Introduction to Computer Page 3 Babbage's Difference Engine  Charles Babbage developed a machine called difference engine in 1822.  This machine was expected to calculate logarithm tables to a high degree of precision.  The difference engine was made to calculate various mathematical functions. Babbage's Analytical Engine  Charles Babbage developed this mechanical general-purpose computer in 1873.  Babbage's first attempt at a mechanical computing device was the difference engine, a special-purpose calculator designed to tabulate logarithms and trigonometric functions by evaluating finite differences to create approximating polynomials. Hollerith's Machine  The tabulating machine was an electrical device designed to assist in summarizing information and, later, accounting.  Invented by Herman Hollerith, the machine was developed to help process data for the 1890 U.S. Census.  It spawned a larger class of devices known as unit record equipment and the data processing industry. Mark - 1  The electromechanical ASCC was devised by Howard H. Aiken, built at IBM and shipped to Harvard in February 1944.  The main advantage of the Mark I was that it was fully automatic-it didn't need any human intervention once it started. It was the first fully automatic computer to be completed and also very reliable.  It is considered to be ‘the beginning of the era of the modern computer’ and ‘the real dawn of the computer age’. ABC – Atanasoff Berry Computer  First digital electronic computer built between 1937 – 1942  John Vincent Atanasoff & Clifford Berry  Uses punched cards for input and output, vacuum tube electronics to process data in binary format, and rotating drums of capacitors to store data  Performs single task, built to solve large systems of simultaneous equations  Onerous computing task commonly found in science and engineering Colossus  Alan Turing and Max Newman in England starting 1943  Special purpose electronic computer ENIAC – Electronic Numerical Integrator And Calculator  The first General-Purpose Electronic Computer  John Mauchly & J Presper Eckert  Weighing 30 tons, used 18,000 vacuum tubes and used 200 kilowatts of electrical power  Can be programmed (given different sets of instructions to follow) by the cumbersome procedure of reconnecting cable and flipping switches EDVAC – Electronic Discrete Variable Automatic Computer  John Von Neumann  The first stored program computer EDSAC – Electronic Delay Storage Automatic Computer  Maurice Wilkes at University of Cambridge, England  Inspired by Neumann’s EDVAC  second usefully operational electronic digital stored-program computer UNIVAC I – Universal Automatic Computer  First commercial computer  Remmington Rand Corporation  John Mauchly & J Presper Eckert  IBM – International Business Machine Introduction to Computer Page 4 Generations Of Modern Computers 1st generation: Vacuum Tubes  These computers used vacuum tubes for circuitry and magnetic drums for memory, were often enormous (taking up entire rooms), expensive to operate and in addition to using a great deal of electricity, generated a lot of heat.  It relied on machine language, the lowest-level programming language understood by computers, and they could only solve one problem at a time. 2nd generation: Transistors (Solid State & Magnetic Core)  The transistor allowed computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors.  Though it still generated a great deal of heat, it was a vast improvement over the vacuum tube.  These computers moved from binary machine language to symbolic or assembly languages, which allowed programmers to specify instructions in words. 3rd generation: Integrated Circuits (Integrated Solid State Circuits)  Transistors were miniaturized and placed on silicon chips which drastically increased the speed and efficiency of computers.  Users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allows the device to run many different applications at one time with a central program that monitored the memory. 4th generation: Large Scale Integration (LSI) (Microprocessors)  The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip.  The Intel 4004 chip, developed in 1971, located all the components of the computer-from the central processing unit and memory to input/output controls, on a single chip.  They could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices. 5th generation: Very Large Scale Integration (VLSI) (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.  Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come.  The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.  Artificial Intelligence is the branch of computer science concerned with making computers behave like humans. The term was coined in 1956 by John McCarthy at the Massachusetts Institute of Technology. Artificial intelligence includes:  Games Playing: programming computers to play games such as chess and checkers  Expert Systems: programming computers to make decisions in real-life situations (for example, some expert systems help doctors diagnose diseases based on symptoms)  Natural Language: programming computers to understand natural human languages  Neural Networks: Systems that simulate intelligence by attempting to reproduce the types of physical connections that occur in animal brains  Robotics: programming computers to see and hear and react to other sensory stimuli Types of Computer  According to PURPOSE  General Purpose Computers  a machine that is capable of carrying out some general data processing under program control. Introduction to Computer Page 5   computers that follow instructions, thus virtually all computers from micro to mainframe are general purpose. Even computers in toys, games and single-function devices follow instructions in their built-in program  Special Purpose Computers  A computer that is designed to operate on a restricted class of problems.  Use special purpose computer equipment to obtain patient diagnostic information  According to TYPE OF DATA HANDLED  Analog Computers - computers that recognize data as a continuous measurement of a physical property (voltage, pressure, speed and temperature). Example: Automobile speedometer  Digital Computers - high speed programmable electronic devices that perform mathematical calculations compare values and store results. They recognize data by counting discrete signal representing either a high or low voltage state of electricity  Hybrid Computers - A computer that processes both analog and digital data  According to CAPACITY  Supercomputers are widely used in scientific applications such as aerodynamic design simulation, processing of geological data.  Supercomputers are the most powerful computers. They are used for problems requiring complex calculations.  Because of their size and expense, supercomputers are relatively rare.  Supercomputers are used by universities, government agencies, and large businesses  Mainframe computers are usually slower, less powerful and less expensive than supercomputers. A technique that allows many people at terminals, to access the same computer at one time is called time sharing. Mainframes are used by banks and many businesses to update inventory etc.  Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.  Mainframe computers are used in large organizations where many users need access to shared data and programs.  Mainframes are also used as e-commerce servers, handling transactions over the Internet.  Minicomputers  are smaller than mainframe, general purpose computers, and give computing power without adding the prohibitive expenses associated with larger systems. It is generally easier to use.  Minicomputers usually have multiple terminals.  Minicomputers may be used as network servers and Internet servers.  MICROCOMPUTERS – personal computers  These are digital computer system that uses a microprocessor (the CPU on chip), a read-only memory (ROM), and random-access memory (RAM)  The smallest, least expensive of all the computers.  Micro computers have smallest memory and less power, are physically smaller and permit fewer peripherals to be attached. Major varieties:  DESKTOP COMPUTERS - a PC that is not designed for portability. Usually sit in one place on a desk or table and are plugged into a wall outlet for power. the case of the computer holds the motherboard, drives, power supply, and expansion cards. This case may lay flat on the desk, or it may be a tower that stands vertically (on the desk or under it)  LAPTOP COMPUTERS - portable computers that integrate the display, keyboard, a pointing device or trackball, processor, memory and hard drive all in a battery-operated package slightly larger than an average hardcover book Introduction to Computer Page 6   PERSONAL DIGITAL ASSISTANT (PDA) - a handheld microcomputer that trades off power for small size and greater portability. Typically use a touch-sensitive LCD screen for both output and input (the user draws characters and presses icons on the screen with a stylus)  communicate with desktop computers and with each other either by cable connection, infrared (IR) beam, or radio waves.  normally used to keep track of appointment calendars, to-do lists, address books, and for taking notes.  PALMTOP or HANDHELD PC - a very small microcomputer that also sacrifices power for small size and portability. These devices typically look more like a tiny laptop than a PDA, with a flip-up screen and small keyboard. They may use Windows CE or similar operating system for handheld devices. COMPONENTS OF ELECTRONIC DATA PROCESSING SYSTEM 1. HARDWARE 2. SOFTWARE 3. PEOPLE/HUMANWARE 1) HARDWARE  refers to the physical components of the computer system  consist of the devices within the case of the computer itself, and any peripheral devices that are connected to the computer (such as the mouse and keyboard)  primary component of the computer is the motherboard (also called the main circuit board, main logic board, mainboard, or system board), The motherboard is a large printed circuit board with microchips, connectors, and other components mounted on it, and with copper circuitry traces that connect the components together A motherboard typically holds the following items:  CPU (Central Processing Unit) where the actual processing of data takes place  System clock circuitry (that keeps all of the digital chips in lockstep)  Other controller chips that act as traffic cops directing data flow along the system busses (the circuitry connecting the chips to the CPU) and I/O ports.  RAM (the main memory, plus additional slots for adding more memory)  ROM (containing the BIOS-Basic Input Output System)  “CMOS” – Complementary Metal Oxide Semiconductor  Expansion slots (for adding expansion cards such as Video cards and Sound cards)  Power supply (to convert the AC line current from the wall outlet to the low-voltage DC current used by the computer)  several storage devices located in the expansion bays of the case (such as: hard drives, floppy drives, Zip drives, and CD drives, and DVD drives) CENTRAL PROCESSING UNIT (CPU/PROCESSOR)  the component of the personal computer that does the actual processing of data.  the central processing unit (CPU) that fits on one microchip.  it is the “brain” of the computer  the microprocessor integrated circuit package holds a silicon chip that contains millions of transistors and other components fabricated into the silicon. Because the transistors on the chip are very tiny, even a small zap of high voltage current (such as from static electricity) can destroy a chip. PARTS OF THE CPU  CONTROL UNIT: The control unit is responsible for loading and interpreting the individual instructions that comprise the computer program. These instructions are in a language called machine code. Machine code is a pattern of ones and zeros. The control unit also has the task of getting the data needed by the instructions and returning the results of the processing after the instruction has been executed.  ARITHMETIC-LOGIC UNIT: The ALU is responsible for carrying out arithmetic operations such as addition and subtraction as well as logical decisions such as whether one number is bigger than another. All programs consist of complex sets of arithmetic and logical operations. Another way of thinking of a logical operation is as a decision making operation. Introduction to Computer Page 7   ON-BOARD CACHE MEMORY: Because the CPU can perform its operations much faster than data can be transferred from RAM, many CPUs have on-board cache memory. This is memory that the control unit can access very quickly and use for intermediate storage. Further, data and instructions can be loaded into cache before they are actually needed. When they are needed, the transfer is much faster than it would have been if RAM had been used. Functional organization of the basic computer system architecture Input C Contr P Arith Mem U Output Exter nal MEMORY  The memory of a microcomputer is where programs and data are stored when they are currently in active use.  Kinds of memory microcomputer contains:  RAM (Random Access Memory) o RAM is used to store the current data and programs while ROM is used to store the routines that enable a computer to boot up. o the main memory space of your computer o RAM consists of banks of microchip transistors that are either on or off (representing a 1 or a zero). o RAM chips need constant power to remember what is stored in them; a power interruption of even a fraction of a second (perhaps caused by nearby lightning) can cause the RAM to lose its contents. o RAM is said to be volatile (from “easily evaporated”) o RAM is usually installed into sockets on the motherboard as DIMMs (Dual Inline Memory Module), small circuit boards that hold the RAM chips. o RAM size is measured in bytes, kilobytes, megabytes, etc. o two types of memory:  Random access, in which any bit of memory could be addressed at any moment; and  Sequential memory (such as data stored on tape) where bits could only be accessed in a certain order o Types of RAM  FPM RAM (Fast Page Mode RAM)  DDR SDRAM (Double-Data-Rate SDRAM)  EDO RAM (Extended Data Out RAM)  RDRAM (Rambus Dynamic RAM)  SDRAM (Synchronous Dynamic RAM)  ROM (Read Only Memory) o ROM does not need power to remember its contents, so this is where a computer stores the programs that are needed to start up (boot up) the computer system o When the computer is first turned on, the program stored in the ROM is feed to the processor o The startup instructions stored on ROM in a PC are part of the BIOS (Basic Input Output System). The BIOS also contains the low-level interface code needed to access the drives, keyboard, and produce simple display output Introduction to Computer Page 8  o The motherboard includes special circuitry that allows the “permanent” contents of the chip to be updated if needed, but this is rarely done (EEPROM can only be re-written a limited number of times—but that limit may be 10,000 times  CMOS (Complementary Metal Oxide Semiconductor o is a type of transistor memory that requires very little power to store data, so this type of chip was used in the early days for storing semi-permanent data o is a small amount of “semi-permanent” storage where changeable data can be stored that needs to remain available while the computer is turned off. A small battery on the motherboard keeps the CMOS ‘alive’ when power is off RAM ROM Store the currently active programs Stores certain fixed routines such as the Function and their data. boot-up routines. RAM is volatile: When the computer ROM is non-volatile: When the computer Volatility is switched off, the contents are lost. is switched off, the contents are not lost. The contents of RAM can be The contents of ROM cannot be changed Changeable changed or deleted. or deleted. MEMORY MEASUREMENT  BITS o In computer components - data and instructions are stored as patterns of ones and zeros. These individual ones and zeros are called bits. o In electronic components the one is stored by switching an electronic switch on and a zero by switching it off. o On a magnetic material, such as the surface of a hard disk, the one may be stored with a clockwise magnetic field and a zero with a counter-clockwise field. o The reason for the use of only ones and zeros stems directly from the fact that modern circuitry makes use of electronic switches and these can only be on or off. The term for circuitry based on switches is digital. Arithmetic based on the use of only ones and zeros is called binary arithmetic.  BYTES o Bits are grouped together into sets of eight. A set of eight bits is called a byte. o ASCII or American Standard Code for Information Interchange was a system of representing all the characters of the western alphabet and certain special characters in a single byte. You can think of the byte as the amount of memory required to store a single character. o As there are only 256 possible variations within eight bits, this is not sufficient to represent other alphabets. As a result a new system, called uni-code, has been developed to represent all the alphabets of the world. This makes use of two bytes or sixteen bits. With two bytes, 65536 different characters and symbols can be represented. UNITS OF MEMORY  Because of using very large numbers of bytes for storage, abbreviations are used for large numbers.  These are based on powers of two and are set out as shown in the following table. 10 kB kilobyte 2 = 1 024 bytes approx. 1 000 bytes 20 Mb Megabyte 2 = 1 048 576 bytes approx. 1 000 000 bytes 30 Gb Gigabyte 2 bytes approx. 1000 000 000 bytes Introduction to Computer Page 9  40 Tb Terabyte 2 bytes approx. 1000 000 000 000 bytes When working with files and directories, you often need to know how large the files are or how much space a directory and its files occupies.  BIT is the smallest unit, represented by 1 or 0  One BYTE is one character which is a number, letter or symbol. It consists of eight bits (binary digits) and is the smallest unit of information a computer can process.  One KILOBYTE is 1,024 characters and is approximately equal to one page of text in double-spacing.  One MEGABYTE is 1,048,576 characters and is approximately equal to one book.  One GIGABYTE is 1,073,741,824 characters and is approximately equal to 1000 books.  One TERABYTE is 1,099,511,627,776 characters and is approximately equal to a whole library. Computer Performance The performance of a computer is determined by a number of factors, all of which work together. Often a single item that is functioning poorly will cause a bottleneck resulting in poor performance  CPU: The model of the CPU and its speed are the first factors that determine computer performance. Generally, the CPU so far outperforms the other components that poor performance is usually due to other factors. One important factor in the performance of the CPU is the amount of on-board cache memory. If the CPU has sufficient cache memory it can queue future instructions and data in cache. Since access to cache memory is far faster than that to RAM, the overall processing performance is improved. On-board cache memory helps especially where the CPU is involved in processing of graphics.  RAM: If a computer does not have sufficient RAM, it has to make use of the hard disk to store intermediate data that it would normally store in RAM. This is referred to as virtual memory. Since hard disk access is much slower than access to RAM, this will slow down the computer. The more RAM a computer has, the less need there will be to make use of virtual memory.  Graphics cards: The graphics card is the unit that converts the signals from the CPU into a form that can be displayed on the monitor. A good graphics card can take over many of the tasks of the CPU in generating the output. This leaves the CPU free to do other processing tasks. The quality of the graphics card is a key factor in the performance of a computer, yet is one which is often overlooked.  Number of applications: Modern computers are designed to run more than one application at a time and to allow applications to be working on multiple sets of data at the same time. For example, a user may be working on four documents at once. However, the more open applications and documents there are, the more this will place a burden on the processing power of the computer. For best performance, only open the applications and documents you need. Close others. PORTS  serves as an interface between the computer and other computers or peripheral devices.  physically, a port is a specialized outlet on a piece of equipment to which a plug or cable connects.  electronically, the several conductors making up the outlet provide a signal transfer between devices.  Kinds of Ports  Serial Port - transmits data one bit at a time. Typically on older PCs, a modem, mouse, or keyboard would be connected via serial ports. Serial cables are cheaper to make than parallel cables and easier to shield from interference Introduction to Computer Page 10   Parallel Port - transmit 8 bits of data at a time, so it was faster than the old serial port. The parallel port was typically used to connect a printer to the computer.  USB (Universal Serial Bus) - is a newer type of serial connection that is much faster than the old serial ports. USB is also much smarter and more versatile since it allows the “daisy chaining” of up to 127 USB peripherals connected to one port.  FireWire (IEEE 1394) - one of the fastest peripheral standards ever developed, which makes it great for use with multimedia peripherals such as digital video cameras and other high-speed devices like the latest hard disk drives and printers  SCSI (Small Computer System Interface) pronounced “scuzzy,” is an older high-speed interface technology. Up to six devices can be daisy-chained to a SCSI port on your computer, but, unlike the plug- and-play nature of USB and FireWire, the user must manually set the SCSI ID number of each device and add connection terminators as needed. In other words, it was a much bigger pain than the newer interfaces.  PCMCIA (Personal Computer Memory Card International Association or PC Card) - is a standard for extension cards for mobile computers. PCMCIA cards are about the size of a credit card and are typically inserted into a slot in the side of your laptop. The card may contain extra memory (which was it primary original use) or it may contain expansion peripherals such as a modem, a tiny hard disk drive, a networking adapter, etc. Type I, II, and III cards are different thicknesses  ETHERNET - Connecting your computer to a network requires a network adapter. This circuitry and port could be built into the motherboard (as is often the case in laptops and Macs), or your computer may have a network interface card (NIC) in one of its expansion slots. Your computer also needs the necessary networking software installed. Ethernet comes in different speed ratings, such as 10 megabits/sec, 100 megabits/sec, and gigabit/sec speeds.  PS/2 (Personal System 2) - A type of port developed by IBM for connecting a mouse or keyboard to a PC. The PS/2 port supports a mini DIN plug containing just 6 pins. Most PCs have a PS/2 port so that the serial port can be used by another device, such as a modem. The PS/2 port is often called the mouse port.  Audio Ports - is a stereo output bus that accommodates up to 64 Audio tracks  ISA (Industry Standard Architecture) – an 8-bit computer bus standard for IBM compatible computers  PCI (Peripheral Component Interconnect) - is a computer bus used for attaching peripheral devices to a computer motherboard  AGP (Accelerated Graphics Port) - is an interface specification that enables 3-D graphics to display quickly on ordinary personal comp  PCIE (PCI Express) - is a brand new interface developed using PCI programming concepts. PCI Express features a serial physical-layer protocol and various connectors. PCI Express is expected to replace the PCI and PCI derived AGP buses in the future.  IDE (Integrated Drive Electronics) - a standard type of connection for storage devices in a PC. Generally, it refers to the types of cables and ports used to connect some hard drives and optical drives to each other and to the motherboard.  ATA (Advanced Technology Attachment) - It is a type of disk drive that integrates the drive controller directly on the drive itself. Computers can use ATA hard drives without a specific controller to support the drive  SATA (Serial ATA) - is an IDE standard for connecting devices like optical drives and hard drives to the motherboard using a long, thin, 7-pin SATA cables. One end plugs into a port on the motherboard, usually labeled SATA, and the other into the back of a storage device like a hard drive. The term SATA generally refers to the types of cables and connections that follow this standard. PERIPHERALS  Peripherals are devices that are attached to a computer system to enhance its capabilities.  Peripherals include: o input devices – are machines or physical equipments that feed data into the CPU of the computer o output devices - are machines or physical equipments that write data into output media readable by humans o storage devices - are machines or physical equipments that store data into secondary storage o communication devices - are machines or physical equipments used to transmit information using communication facilities (Networking topic) Introduction to Computer Page 11   All peripherals must have some way to access the data bus of the computer (the communications channel on the motherboard that connects the processor, RAM, and other components). To do this, peripherals are connected via some kind of port (also called a I/O port, for input/output) on the computer (and a cable with the proper connectors is needed). INPUT DEVICES - Any device which allows the user to send data or instructions to the computer. It is either the use of any mechanical movement, sound, light, heat or electronic signals to input data and instructions.  KEYBOARD - The most familiar input device. Users type the text directly into the computer. o There are a number of layouts of the keyboard. The most important are the language variations. TYPES OF KEYBOARD o QWERTY by Christopher Sholes in 1868 o refers to the arrangement of keys on a standard English computer keyboard or typewriter o The name derives from the first six characters on the top alphabetic line of the keyboard. o DVORAK by August Dvorak in the 1930s  A keyboard designed for speed typing. Designed so that the middle row of keys includes the most common letters. In addition, there are two additional Dvorak keyboards, a left-handed and right-handed keyboard. These keyboards are designed for people who have only one hand for typing  MOUSE - a point and click device. As you move the mouse across a surface, it senses this movement either mechanically or optically. This is translated into the movement of a pointer on the screen. Functions are represented as icons on the screen. When you click on these using a mouse button, the function is executed. Mouse functions: CLICK, DOUBLE CLICK, CLICK & DRAG  TOUCHPAD - a device that senses pressure to guide the pointer on the computer screen. It is generally a small square area below the keyboard. As the user moves his/her finger across the touchpad, the pointer moves on the screen. Next to the pad are two buttons used for clicking in exactly the same way as those on a mouse.  TRACKBALL - acts as a type of overturned mouse. The ball is on the top side of the object. By rolling the ball you can move the pointer across the screen. Some keyboards have an in-built trackball. The trackball has been superseded by the touchpad  BAR CODE READER - a device that can read and interpret bar codes and input the data into the computer o bar code -a pattern of vertical lines in which the spacing and thickness can be used to represent data  JOYSTICK - a device that is familiar for use in games to move objects on the screen. However, it is also used to control the movements in computerized industrial machines such as lathes. It consists of a small vertical lever which can move in any direction. These movements are translated to the computer which in turn uses them to control the movements of machinery  LIGHT PEN - a device which is sensitive to variations in patterns on a surface. Light pens act like a miniature scanner and can read text as they are dragged across the printed page. This can be transferred directly to the current open document  DIGITAL CAMERA o Instead of film, a digital camera uses a light sensitive screen at the back of the camera. A small computer inside the camera converts the pattern on the screen into a standard graphics file which can then be transferred to a computer  MICROPHONE - translates speech into an electronic signal. Modern speech recognition software is able to translate this into either commands or data.  SCANNER o A scanner is similar to a photocopier, except that instead of producing a paper copy of the document you place on it, you get an electronic copy which appears on your computer screen. o Text recognition software can be used with a scanner. This software is able to recognize the individual letters in the image. Instead of creating a single image of the document, the software inserts actual text into your application which can then be edited. OUTPUT DEVICES - Any device that the computer uses to send the results of processing to the user. The output can be a hard copy (paper), visual or sound. Introduction to Computer Page 12   VISUAL DISPLAY UNIT (VDU) o Virtually, all computers use some type of screen as their primary output device. o There are two categories of screen: o Cathode ray tube (CRT) - usually called a monitor o Solid state screens - Also known as LCD (Liquid Crystal Displays) or LED (Light Emitting Display). Make use of tiny transistors to emit light and create an image.  PRINTERS - produces hard copy of the output on paper o There are three main types of printer: o Dot matrix o Inkjet o Laser  SPEAKERS o Modern computers using the appropriate software can turn text in a document into audible speech. This is known as speech synthesis. Other types of software allow music and other sounds to be created and played back. Computers are able to play music directly from a CD or play a film from a DVD. In all cases, the sound is transmitted through a speaker in the same way it is in a sound system or radio. INPUT-OUTPUT DEVICES - devices that function as both input and output devices  TOUCH SCREEN - a special type of screen in which the screen not only displays output but also responds to being touched  PDAs have touch sensitive screens. You would use a special stylus to touch icons on the screen or to write. Character recognition software then converts your writing to input text for the PDA STORAGE DEVICES - a device for recording (storing) information (data). Recording can be done using virtually any form of energy, spanning from manual muscle power in handwriting, to acoustic vibrations in phonographic recording, to electromagnetic energy modulating magnetic tape and optical discs. Storage devices retain items such as data, instructions, and information for retrieval and future use.  DISKETTE - comprises a plastic flexible disk enclosed inside a tough plastic cover. At one end is a window. When the diskette is placed inside a diskette drive, the window is pushed to the side. The read- record head inside the drive makes contact with the magnetic disk.  ZIP DISK - a removable magnetic disk which fits into a special zip drive. The surface is coated with a special scratch resistant material which makes a zip disk a very robust storage device. It comes in a number of capacities: 100, 250 and 750 Mb. The speed of a zip drive is faster than all but the very fastest of CD drives. Its robustness and speed make it an excellent backup device.  DATA CARTRIDGE - a tape very similar to that found in a tape recorder, only much higher quality. These are used in a device called a tape streamer to record data. Data cartridges, especially if good quality, are reliable and cheap devices for creating backups of large quantities of data. They are, however, rather slow. Data cartridges are sequential devices which mean that to access an item of data on them, all the preceding data reads to be read first. They are tending to become obsolete as newer faster and more reliable technologies are available. A single tape can stored many Gb of data  CD ROM - uses optical technology. When data is written, small pits are burned into the surface using a highly focused laser beam. These are read by another laser beam. CD ROM provides a reliable and storage medium for backing up and storing data. The speed is greater than that of a diskette but slower than that of a hard drive. Writing to a CD ROM is a much slower process than reading it. The capacity of a CD ROM is 640 Mb. It is sometimes possible to store about 700 Mb on a disk. o There are two types of CD ROM used for storage. The CD-W disks can only be written to once. CD- RW disks are designed so that one set of data can overwrite another. This allows the disks to be re- used many times.  DIGITAL VERSATILE DISK (DVD) - a development of the storage technology of the CD ROM. Using newer storage methods and higher quality media, a DVD can store about 4 Gb of data. This is enough to store a full length film.  HARD DISK - can be internal or external. An internal drive is housed inside the main unit and is connected directly to the motherboard of the computer. An external drive is housed inside a special Introduction to Computer Page 13  caddy which connects to the computer through one of its ports. Most now use the USB or firewire ports to achieve maximum performance.  FLASH DISK or MEMORY STICK - a solid state device (no moving parts) that connects to the computer via the USB port. It provides a very fast and reliable method of storing data externally. 2) SOFTWARE o written programs or procedures or rules and associated documentation pertaining to the operation of a computer system and that are stored in read/write memory o refers to all computer programs that direct and control the computer hardware in data processing o these are programs that tell the computer what steps to take, what data to work on and what to do with the results o Types of Software  SYSTEM SOFTWARE  refers to all programs that manages all the system resources including user’s program  It forms a link between the application program and the hardware devices and the circuitry necessary to execute the program of instructions  the term used to described programs that enable the computer to function  improve its performance and access the functionality of the hardware  sole function is the control of the operation of the computer  System Software includes o OPERATING SYSTEM - is an interface between hardware and user; responsible for the management and coordination of activities and the sharing of the resources of the computer; acts as a host for computing applications that are running on the machine.  Examples of operating system Linux / Variants MacOS MS-DOS IBM OS/2 Warp Unix / Variants Windows CE Windows 3.x Windows 95 Windows 98 / SE Windows ME Windows NT Windows 2000 Windows XP Windows Vista Windows 7 Windows 8  Functions of operating system  Boot-up the computer.  Control the hard drives: This includes such features as formatting and defragmenting disks as well as saving files to and retrieving files from disk.  Control input devices such as keyboards, mice and scanners and output devices such as the video display and printer.  Control the external ports  Provide the functionality for computers to be linked in a network  Provide the foundation for application software to be launched.  Enable application software to access and use the hardware o DEVICE DRIVERS or software driver - is a computer program allowing higher-level computer programs to interact with a hardware device o SERVERS - is any combination of hardware or software designed to provide services to clients o UTILITIES - (also known as service program, service routine, tool, or utility routine) is a 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. Some utility software has been integrated into most major operating systems o WINDOWING SYSTEMS - is a component of a graphical user interface (GUI), and more specifically of a desktop environment, which supports the implementation of window managers, and provides basic support for graphics hardware, pointing devices such as mice, and keyboards Introduction to Computer Page 14   APPLICATION SOFTWARE  is a program that functions and is operated by means of a computer, with the purpose of supporting or improving the software user's work.  programs designed to meet the needs of the individual users  a type of software that forms a link between the computer and the people who need data processing services  Also called as END-USER PROGRAMS  Types: o COTS (Commercial Off-the-Shelf) or Packaged Software o Customized Software  EXAMPLES OF APPLICATION SOFTWARE Application Brand names Function OpenOffice Writer, StarWriter, Word Create, store, format and edit documents, letters and articles. Word KWord, Microsoft Word, Lotus processor processors are used where the emphasis is on manipulation of text. Ami Pro, Corel WordPerfect OpenOffice Calc, StarCalc, Create financial statements, balance sheets, perform statistical and Spreadsheet KSpread, Microsoft Excel numerical analysis of data, and make forecasts based on numeric data. Quattro Pro, Lotus 123 Spreadsheets are used where the emphasis is on arithmetic. OpenOffice Impress, Presentation StarImpress, KPresenter Create slide shows, lectures, seminars and other types of presentation. Microsoft PowerPoint Sybase, MySQL Store and convert data into information. Databases are particularly Database Microsoft Access useful in working with large quantities of data. Evolution, KMail Email client Send, receive, store and organise electronic mail. Microsoft Outlook Mozilla, Netscape Web browser Surf the Internet and view web sites. Microsoft Internet Explorer Desktop Microsoft Publisher DTP is similar to word processing except that there is more emphasis on publishing/DTP Page Maker page layout and the integration of diagrams. Web Dreamweaver Create web sites that can be read by a browser. development Microsoft FrontPage Graphics and The GIMP Create and manipulate graphics images and store images in a variety of imaging Adobe Photoshop formats. 3) HUMANWARE / PEOPLEWARE o refers to anything that has to do with the role of people in the development or use of computer software and hardware systems, including such issues as developer productivity, teamwork, group dynamics, the psychology of programming, project management, organizational factors, human interface design, and human-machine-interaction o Roles played by people o Users & Customers – establish needs and ultimately use the results delivered by computers o System Development Specialist (SDS) – people who specializes in working with the users to develop systems that will do the job and produce the results required o Programmers – people who write the instructions that process data o Computer Operations Personnel  Encoder – responsible for data entry  Console Operators – responsible for controlling, scheduling and monitoring the running of jobs on the computer Introduction to Computer Page 15   Peripheral Operators – responsible for operating the input, output, storage and other hardware devices within the computer system  Data Librarian – responsible for maintaining the inventory of programs, operating manuals, and data storage media to make sure that all of these resources are accounted for and available when needed o Technical Support Personnel  System Programmers – maintain the operating system and other system software to ensure that the computer is providing the needed services to the system development specialists, programmers, operators and users  Hardware Specialists – ensures that the specifications for the needed hardware is met Introduction to Computer Page 16