Chapter 2: Computer Hardware and Software PDF

CHAPTER 2 COMPUTER HARDWARE AND SOFTWARE 2.1 An Overview Of Computers 2.2 Data Representation 2.3 Computer Hardware 2.4 An Overview of Software 2.1An Overview of Computers 2.1.1Computers: Mind Tools Computers have been called “mind tools” because they e...

CHAPTER 2 COMPUTER HARDWARE AND SOFTWARE 2.1 An Overview Of Computers 2.2 Data Representation 2.3 Computer Hardware 2.4 An Overview of Software 2.1An Overview of Computers 2.1.1Computers: Mind Tools Computers have been called “mind tools” because they enhance our ability to perform tasks that require mental effort. Computers are adept at performing activities such as making calculations quickly, sorting large lists, and searching through vast information libraries. Human can do all these activities, but a computer can often accomplish them much more rapidly and more accurately. Our ability to use a computer complements our mental capabilities and may make us more productive. The key to making effective use of the computer as a tool is to know what a computer does, how it works, and how you can use it. A computer system typically includes a computer, peripheral devices, and software. The electronic and mechanical devices that manipulate data are known as hardware. The term “hardware” refers to the computer itself and components called peripheral devices that expand the computer’s input, output, and storage capabilities. Computer hardware in and of itself does not provide a particularly useful mind tool. To be useful, a computer requires a computer program or software, which is a set of instructions that tells a computer how to perform a particular task. Computers can become even more effective when connected to other computers so that people can share information. 2.1.2 Definition of computer A Computer can be thought of as an electronic device that is capable of doing the following tasks:  Accept data in some prescribed form as an input  Process the data according to pre-established instructions or procedures Page 1   Provide the desired information in a suitable output format and medium.  Store data, instruction, and information (processed data) for further and future use. A computer accepts input: Examples of the kinds of input a computer can process include the words and symbols in a document, numbers for a calculation, pictures, audio signals from a microphone, and instructions for completing a process. A computer processes data: Data refers to the symbols that represent facts and ideas. Computer manipulate data in many ways, and we call this manipulation “processing”. Some of the ways that a computer can process data include performing calculations, sorting list of words or numbers, etc. In the context of computers, then, we can define a process as a systematic series of actions that a computer uses to manipulate data. A computer process data in a device called the central processing unit (CPU) which we will see in more detail later. A computer stores data: A computer must store data so that it will be available for processing. Computer typically have more than one location for storing data, depending on how the data is being used. The computer puts data in one place while it is waiting to be processed and, in another place, when it is not needed for immediate processing. Memory is an area of a computer that holds data that is waiting to be processed. Storage is the area where data can be left on a permanent basis while it is not needed for processing. A Computer produces output: Computer output is the results produced by a computer. The word “output” is also a verb that means the process of producing output. Some examples a computer output include reports, documents, music, graph, and pictures. An output device displays, prints or transmits the result of processing. Research is also being conducted that would replace the keyboard with a means of using voice or handwriting for input. Currently these types of input are imprecise because people pronounce and write words very differently, making it difficult for a computer to recognize the same input from different users. However, advances in this field have led to systems that can recognize a small number of words spoken by a variety of people. In addition, software has been developed that can be taught to recognize an individual's handwriting Page 2 2.1.3 Characteristics of Computer The characteristics of a computer shows the capability and the potential of the computer for processing data. This saves time, space, money, labour etc. Some of the basic characteristics of computer are: -  Speed The most important characteristic of a computer is its speed. Computer works only one step at a time. Its speed is measured by the amount of time it took to perform or carry out a basic operation. Computer speed measured in terms of micro second (10-6 one millionths), nano second (10-9 one billionths), and Pico second (10-12 one trillionths).  Storage A computer can store large amount of information in a few numbers of disks. And the time it took to retrieve or process a single information is not more than a micro or a nano second. In general, a computer has a capacity to store a very large amount of information in organised manner so that accessing information is very fast. Note:  Computer is efficient because it can store large amount of information within a limited space in a very organized manner  Computer is fast because it can access the stored information in a fraction of a second  Accuracy Now a day’s computers are being used for surgical purposes which needs almost hundred percent accuracy. From this we can understand that computer is accurate and consistent. Unless there is an error in the input data or unreliable program the computer processes with a very accurate.  Automatic Once necessary information and program is feed to the computer, it performs processing without human intervention.  Diligence A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it overpowers human being in routine type of work. Page 3  Versatility It means the capacity to perform completely different type of work. You may use your computer to prepare payroll slips. Next moment you may use it for inventory management or to prepare electric bills. 2.1.4 Limitations of computers  No IQ Computer is a dumb machine and it cannot do any work without instruction from the user. It performs the instructions at tremendous speed and with accuracy. It is you to decide what you want to do and in what sequence. So a computer cannot take its own decision as you can. Hence computers do not think.  No Feeling It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even after long hours of work. It does not distinguish between users.  Computers are not self-directing machines: They cannot instruct themselves & they are not independent machines. Once computers are fed the desired instruction, they can perform what they have been ordered.  Computer cannotsympathize (feel sorry for)  Computer cannot do by trial and error 2.1.5Applications of computers Why we use Computers? The following are some of the capabilities and potential of Computers, which are reasons for using Computers. Today computers are used almost in any field Medicine – Patient monitoring, diagnosis, controlling parameters etc Learning – Digital libraries, learning tools, etc Page 4  Engineering – Better drawing, automated manufacturing plants Entertainment – Music composition, movie animations, games Data Processing and Data Management: – E.g. census analysis, weather forecasting Operations Control in Real time systems – E.g. rocket guidance, Production control, booking Communication – Internet, telephone Routine tasks of repetitive nature – Report generation – Maintenance of accounts – Letter writing – Payroll and inventory controls etc 2.2 Data Representation Data in a computer system is represented by a flow of an electric current through a circuit. The presence (on) or absence (off) of this current is interpreted as 1 and 0. Any data that is manipulated or stored in a computer is treated as a combination of 0 and 1. This is called a binary system as only two digits (0 and 1) are used. 2.2.1Units Of Data Representation  When data is stored, processed or communicated within the computer system, it is packed in units;  Arranged from the smallest to the largest, the units are called bit, byte and word;  These units are based on the binary number system; BIT  Bit (derived from binary digit) is the basic unit of data storage  Bits are the smallest units and can convey only two possible states 0 or 1;  In the computer “ON” is represented by the existence of current and “OFF” is represented by the nonexistence of current  On a magnetic disk, the same information is stored by changing the polarity or magnetised particles on the disk’s surface; BYTE  Bits can be organised into large units to make them represent more and meaningful information;  This large unit is called a byte and is the basic “unit of data representation” in a computer system; Page 5  The commonly used byte contains 8 bits;  Since each bit has two states and there are 8 bits in a byte, the total amount of data that can be represented is 28 or 256 possible combinations;  Each byte can represent a character(a character is either a letter, a number or a special symbol such as +,-,?,*, $, etc  A byte is then used as a unit of measurement in the computer memory, processing unit, external storage and during communication;  In order to expand the measuring capacity of byte we use prefixes listed below  Kilo (K)≈ 103 = 1 Thousand  Mega (M)≈ 106=1 Million  Giga (G) ≈ 109= 1 Billion  Tera (T) ≈ 1012 = 1 Trillion  Peta (P) ≈ 1015= 1 Quadrillion Note: 1 KB = 1024 = 210  1 KB = 210 bytes  1 MB = 220 bytes  1 GB =230 bytes  1 TB = 240 bytes  1 PB = 250 bytes Example: 4MB is approximately equal to ≈ 4 X106 bytes 4MB is exactly equal to = 4 X220 bytes WORD  Word refers the number of bits that a computer process at a time or a transmission media transmits at a time  Although bytes can store or transmit information, the process can even be faster if more than one byte is processed at a once;  A combination of bytes, then form a “word”  A word can contain one, two, three or four bytes based on the capacity of the computer;  Word length is usually given in bits  We say that a computer is an 8-bits, a 16 bit, a 32 bit or a 64 bit computer to indicate that the amount of data it can process at a time;  The large the word length a computer has the more powerful and faster it is. Page 6 2.2.2Data Representation Standards The number of characters that can be represented using the binary system in a computer system is dependent on the number of digits (bits) used for representing a single character. Various countries or organisations have adopted different data representation standards at different times. For example the ASCII standard is discussed below.  American Standard Code for Information Interchange (ASCII) ASCII standard is a coding method that has been adopted in USA for data communication.  Microcomputers using 8-bit word length use 7-bits to represent the basic code.  The 8th bit can be permanently 1 or 0  with 7 bits up to 128 (27 )characters can be coded COMPACT REFERENCE TO THE ASCII CODE Page 7 Page 8  2.3 Computer Hardware A computer system is the integration of 1) Data 2) Hardware 3) Software 4) Human ware Through the interaction of the entire component, a computer system is used to accept input from users, to process the input data, and finally to generate output that will be used by the user. 1. Data WHAT IS DATA? Text, numbers, sound (audio), graphics (images), and video that describe people, events, things, ideas etc UnprocessedText, numbers, sound (audio), graphics (images), and video WHAT IS INFORMATION? Text, numbers, sound (audio), graphics (images), and video used as the basis for human action, judgement or decisions. ProcessedText, numbers, sound (audio), graphics (images), and video 2. Hardware Hardware is the general term for the physical devices that carry out the activities of capturing, processing, storing, and communicating data and information. The hardware of a computer system is categorized into six parts. These are: 1. Input unit/Devices 2. Output unit/Devices 3. Central processing Unit 4. Memory unit (primary Storage) 5. Secondary Storage Unit 6. Communication hardware The following figure shows block diagram representation of the microcomputer system Page 9 a. Input unit/ Devices Input devices are the physical components that the user uses to capture and enter data and instructions into the computer system. Input devices translate user data and instructions into a form that the computer can understand. There are several types of input devices.  Keyboard – usually for character input  Pointing devices o Mouse, trackball, touchpad, touch screen, light pen, joystick –usually for instruction input  Reading devices o Scanner (for graphic input), OCR reader, barcode reader  Sound, image and video input devices o Microphone, Digital Video Camera, Digital Video Camera, Web Cam b. Output Devices Output devices are the components that are used to present the processed output or information in a form that is communicable to the user. The most common output types are:  Display Devices  Display devices are the components that are used to generate output (texts, graphics and video output) in a visual form. Page 10  o Examples of display devices include  Ordinary CRT (Cathode Ray Tube) screens that look like ordinary TV screens  LCD (Liquid Crystal Displays) flat screen such as those used with laptop computers.  Plasma Screens  Data and video projectors  Printer o Device that is used to generate hard copy – printed-paper materials. Printers can be categorised depending on:  How images are made (impact and non-impact printers)  Impact printers are those that make physical contact with the paper, like traditional typewriter. Dot Matrix printer is an example of impact printer.  Non-impact printers use a different technology (without physical contact with the paper) to produce prints on hardcopy. Inkjet and Laser printers are example of non- impact printers.  Speaker o Speakers are used to generate sound output C. Central processing Unit The CPU is the core component of the computer system where the major task of processing data (converting data into information is carried out).. Central Processing Unit – (CPU) of a computer is the brain of the computer that actually converts data into information. It manages and controls the overall functionality of the computer and is a measure of the computing power of the computer system. The main components of the processing unit are:  Arithmetic Logic Unit (ALU) o Performs the mathematical (addition, subtraction, division and multiplication), comparison (greater than, less than, equal), and logical (and, or, not) operation.  Control unit o Responsible for directing the system to carryout various internal tasks, such interpreting and executing program instructions Page 11  o Controls the electronic flow of information, fetching and storing data and instruction from/to registers and memory  Registers o Under the direction of the control unit, registers are the high-speed storage area used by the CPU. They are used to temporarily store data and instruction that relate to the process being executed. Usually computer speed is measured using the system clock speed expressed in the number of clock ticks per second. Clock speed is expressed in megahertz or gigahertz (one million or billion clock ticks per second). The speed of system clock determines the speed at which the processor executes instructions. Other things being equal, computer speed increases with increase in clock speed. Today’s personal computers have clock speed greater than 2.0 GHz, which is still increasing. d. Memory unit (primary Storage) Memory is an internal primary data storage device that is used by the computer system in start-up and during operation. As the CPU cannot process data directly from input device or secondary storage devices, data and instructions have to be loaded to the internal memory before the CPU can process them. Internal memory stores:  Whole or part of the program under execution  Data that is being processed  Operating system that is used to manage the operation of the computer There are two major types of memory, Read Only Memory (ROM) and Random Access Memory (RAM).  ROM is a read-only memory that provides start-up instruction when the computer starts. Information stored in ROM is written only once by the manufacture and cannot be changed by the user. In general:  ROM is memory that cannot be changed.  It can be read, but not modified in any way other than replacing the memory chips themselves.  ROM is used in situations where information must be saved and not altered.  The primary use of ROM in the computer is during the boot process.  The ROM on the computer's motherboard contains instructions that tell the machine how to execute the "boot process".  ROM is not volatile; data stored there are kept permanently. Page 12   RAM is a temporary volatile memory space used to store data and instructions by the computer while performing operations. Data stored in RAM exists as long as power is on. When a computer is turned-off, all the data stored in RAM is flashed forever. Having a large RAM size increases the processing power of the computer as more powerful instructions can be run. The performance of memory is by the amount of bits it can store and speed at which data can be accessed from the memory.  The storage capacity is often expressed in MB or GB. Today’s personal computer memory can store hundreds of megabytes.  The speed at which data is accessed is measured as a fraction of a second, often in nanoseconds (one-billionth of a second). In General:  RAM is where data and instructions are temporarily stored while waiting to be processed.  It is also where results of execution are stored.  It is where instructions and data are stored before being executed, and where the results are placed after execution.  RAM is volatile; data stored there are not kept permanently. When the data are executed, they move from the CPU back to RAM, and then are sent to the designated output device. If power to RAM is lost, so is the data contained there: nothing in RAM is permanently stored. e. Secondary Storage unit/devices Secondary storage devices are internal or external storage devices that are used to store programs and user data for later access. Why Secondary Storage?  Convenience – data store on a secondary storage can be accessed at a latter time, unlike primary storage which stores data temporarily  Economical – secondary storage media is less expensive and hence users can store vast amount data that can be accessed at a latter stage  Reliability – Data on a secondary storage is usually physically safe There are different types of secondary storage devices. The most common storage devices are discussed below. Page 13  a) Magnetic Storage Devices Storage devices coated with a magnetic material that can be electrically influenced to hold information recorded in digital (binary) form. Examples are given below Hard Disk A hard disk contains both the disk and the drive (the slot) that is used to read and write data on the disk. A hard disk uses rigid turning disks to store data and programs. They have read/write heads which can read data from the hard disk and write data to the hard disk. The hard disk drive is sealed. This protects the hard disk drive internals from dust, condensation, and other sources of contamination. Hard disks can store much more data than floppy disks, and access and transmit it faster. Currently an average hard disk can store 60 to 80 GB of data. For both hard disks and floppy disks, data is stored on the surface in sectors and tracks. Magnetic Tape A tape drive, also known as a streamer, is a device that reads data from and writes data to a magnetic tape. It is typically used for archiving or backing up of data stored on hard disks. Magnetic tapes are long lasting and inexpensive storage media. Magnetic tapes are made of thin plastic material coated with magnetic coding. Magnetic tapes look like an audiocassette, but are used to store data. o Data is expressed in terms of density, the number of (bytes) or characters per inch o Usually can store very large amount of data – tape cartridges can store giga bytes and tetra bytes o Sequential data storage and access o Very slow read/write operation  Example of magnetic tape include backup Tape Cartridge  Reel-to-reel magnetic tape is commonly used to store information (backup) Page 14  b) Optical Storage Devices Optical storage is a newer storage technology using a high-power laser beam to burn small holes in a disk's surface coating. Data is represented by the presence and absence of holes in the disk’s surface. Optical media are more durable than tape and less vulnerable to environmental conditions. On the other hand, they tend to be slower than typical hard disks, and hold less data. Compact Disk (CD) A compact disc (CD) is an optical disk used to store digital data.It was originally developed for storing digital audio. Types of CDs The different types of CDs include: CD-ROM, CD-R, and CD-RW: CD-ROM (Compact Disc – Read Only Memory): is a version of the CD that allows the information to be stored so that the user can only read from the disks. Once data is recorded on a CD-ROM, new data cannot be stored and the disc cannot be erased. Although CD-ROMs look like music discs, they can only be used with a computer equipped with a CD-ROM drive. CD-R (Compact Disc - Recordable): refers to compact disks that can be recorded only once, but read many times. If the recorded content is no longer wanted, additional material can be recorded only on the remaining space on the disk. The disks themselves are constructed differently from ordinary CDs. CD-RW (Compact Disc - Rewritable): is an extension of CD-R whereby you can rewrite data or audio to the same CD many times. Not all CD drives can read CDRWs. Digital Versatile Disc (DVD) DVD is an optical disc storage media that can be used for storing data, including movies with high video and sound quality. DVDs resemble CD: their physical dimensions are the same – 12 cm or the mini 8cm - but they are encoded in a different format. This enables DVDs to store more data than that of CDs. A typical DVD can often hold more data than 6 CDs. DVDs can store an entire movie, or several hours of audio. Common Types of DVDs Page 15 DVD-ROM: These DVDs are read-only disks. They are accessed using a special DVD drive attached to a personal computer. They are often used for movies (which are more specifically referred to as DVD-Video) and computer games. DVD-R: It offers a write-once, read-many time’s storage format similar to CDR, but can hold more information than a CD-R. DVD-RW: A Rewritable DVD format similar to CD-RW. c. Flash disk/memory Sometimes called (data traveller)/USB Flash/disk-on-key. It is a very convenient secondary storage device. It is pproduced from flash memory chips Note: Data and instructions are moved around inside the computer by means of a bus. The bus carries the data between RAM and the CPU as well as within the CPU itself. e. Microfilm and Microfiche  Store microscopic images of documents on roll or sheet of film  Images recorded using computer output microfilm recorder Page 16  The picture below shows computer output microfilm recorder and rolled microfilm Storage media Life Expectancies f. Communication hardware The hardware used for communication purposes. Example: Network interface card, modem, router, switch etc. Page 17  2.4 An Overview of Software Computer software Software is a term for computer programs. A programis a set of instructions that enables a computer to operate or instructions that tell the computer how to perform a specific task. Computer software has two major categories:  System software  Application software Systems software Systems software includes the computer's basic operating system and language software. The term also usually covers any software used to manage the computer and the network. Thus we can say that systems software includes operating systems, device drivers, programming tools, utilities and more. Operating Systems Operating System or Operating software is a program or a set of programs that serves as anInterface between the users, application programs and the hardware of a computer system. Operating System (OS) is the basic software that controls a computer. It coordinates and manipulates computer hardware, such as computer memory, printers, disks, keyboard, mouse, and monitor; it organizes files on a variety of storage media, such as floppy disk, hard drive, compact disc, digital video disc, and tape; and it manages hardware errors and the loss of data. Operating systems control different computer processes, such as running a spreadsheet program or accessing information from the computer's memory. Page 18 NOTE: In the absence of an operating system a computer equipment will be there with out doing nothing Functions of operating system Operating system has several functions. Some of the major operating system functions are discussed below. I. For Initial set up of the computer II. Checking and managing of the hardware (peripherals, disk drives, memory...) III. Primary Memory Management Memory management is the process of allocating memory to different application. In memory management, the operating system is responsible for:  Keeping track of memory:- the operating system keeps record of the memory usage, including which areas are in use by whom and which areas are available  Deciding which programs to load to memory: – The operating system decides which programs or data to load by allocating and de-allocating memory space to programs  Keeping track of each application separately in memory and preventing the programs from mixing each other. IV. Secondary storage Management The operating system is responsible for the management of the secondary data storage devices, such as magnetic tapes and disks, optical disks. The main function under this area includes:  Supplies all the necessary disk information, such as disk capacity, the space occupied by data and programs, the damaged area in the disk, formatting a disk and informing the available free space on a disk.  Provide tools for efficient use of the secondary storage media–such as disk defragmentation, scandisk, cleanup disk, and backup V. File Management Data stored in any storage device are stored as files, regardless of the different characteristics and physical organisation of the storage devices. The operating system provides a simpler standard logical view of the files stored in the storage devices. The operating system also provides different routines for the management of files including: Page 19   Creation and deletion of files and folders  Manipulation of files and folders – copying, renaming, deleting, printing  Backing up files on permanent storage devices VI. It provides language for users Examples of operating system software: Unix, Windows 95/98/2000/me/xp, MS-DOS Windows NT, PASCAL P6, PC-DOS etc. Types of operating system Several factors can be considered in classifying operating system. Few of factors to consider include: 1. Based on the interface provided by the operating system o Command line Interface (CLI) - users have to enter instruction one by one using the keyboard.  Example: Microsoft Disk Operating System – MS-DOS o Graphical User Interface (GUI) – these operating systems offer an easy to use graphical interface where users can use mouse to enter instruction to the system. With a GUI, a computer user can easily execute commands by clicking on pictures, words, or icons with a pointing device known as a mouse  Example: Windows 95, 98, 2000…, Unix Note:GUI OS generally have the disadvantage of requiring more hardware—such as faster CPUs, more memory, and higher-quality monitors—than do CLI operating systems. 2. Based on the process that they can run at a time I. Single-tasking OS The more primitive single-tasking operating systems can run only one process at a time. For instance, when the computer is printing a document, it cannot start another process or respond to new commands until the printing is completed. II. Multi-tasking OS Page 20 All modern operating systems are multitasking and can run several processes simultaneously. In most computers, however, there is only one central processing unit (CPU; the computational and control unit of the computer), so a multitasking OS creates the illusion of several processes running simultaneously on the CPU. The most common mechanism used to create this illusion is time-slice multitasking, whereby each process is run individually for a fixed period of time. If the process is not completed within the allotted time, it is suspended and another process is run. The processes appear to run simultaneously because the user's sense of time is much slower than the processing speed of the computer. Multi-tasking OS can use a technique known as virtual memory to run processes that require more main memory than is actually available. To implement this technique, space on the hard drive is used to mimic the extra memory needed. Accessing the hard drive is more time-consuming than accessing main memory, however, so performance of the computer slows. Working on MS-Windows xx environment Windows Version xx is an operating system that Microsoft has produced for use on personal computers. An operating system allows your computer to manage software and perform essential tasks. It is also a Graphical User Interface (GUI) that allows you to visually interact with your computer’s functions in a logical, fun, and easy way The first screen appears after you turn on the power of computer is a desktop as shown in the figure below The Desktop is the main Windows xx screen as shown in the figure above. It is the work area where dialog boxes, windows, icons, and menus appear. Like an office desk, the Windows xx desktop contains items you can use to do your job. For instance, from your desktop, you can perform file- Page 21 management tasks and run software applications. You can customize the appearance of the desktop to suit your preferences. The Desktop Components The desktop for Windows xx operating system consists of two main components i. Desktop that contains many components like icons, file, folder, shortcut. Etc. ii. Task Bars 1- Icons: An icon is a graphic image, a small picture or object that represents a file, program, web page, or command. Icons help you execute commands, open programs or documents quickly. To execute a command by using an icon, click or double-click on the icon. It is also useful to recognize quickly an object in a browser list. For example, all documents using the same extension have the same icon. We can classify icons as the following  Folder Icons  File Icons  Shortcut Icons Page 22 Question: What is the function of the task bar? What is the difference between a file, a folder, and a shortcut? All the data on your hard drive consists of files and folders. The basic difference between the two is that files store data, while folders store files and other folders. The folders, often referred to as directories, are used to organize files on your computer. The folders themselves take up virtually no space on the hard drive. Files, on the other hand, is a collection of data stored in one unit, identified by a filename. And filename period file extension can range from a few bytes to several gigabytes. They can be documents, programs, libraries, and other compilations of data. File name consists of two part: - file name and file extension as shown in the figure below A shortcut is a link that points to a program on the computer. Shortcuts allow users to create links to their programs in any folder, Start bar, Taskbar, Desktop or other locations on their computer. A shortcut in Windows is commonly identified by a small arrow in the bottom corner of the icon. Special Icons on the desktop a. Recycle bin: The Recycle Bin is a location (Folder) where deleted files are temporarily stored on Microsoft Windows. The Recycling Bin allows users to recover files that have been deleted in Windows. b. My Computer: My Computer allows the user to explore the contents of their computer drives as well as manage their computer files. Once My Computer is open, you'll see all available drives on your computer. For most users, you'll only be concerned with the Local Disc (C:) drive, which is the hard that stores all your files Page 23 Shutting Down the computer At the bottom of the right pane is the Shutdown button. Click the Shutdown button to turn off your computer. Clicking the arrow next to the Shutdown button displays a menu with additional options for switching users, logging off, restarting, or shutting down. Switch user: If you have more than one user account on your computer, Fast User Switching is an easy way for another person to log on to the computer without logging you off or closing your programs and files. Log off: When you log off from Windows, all of the programs you were using are closed, but the computer is not turned off. Lock: Locking your PC is a good option if you’ll be back soon. You'll have to enter your password when you come back, which helps keep your work more secure. Restart: The Restart button "reboots" your computer (it is sometimes called a "warm boot" or "soft boot.") That means it saves your information to the hard drive, turns off the computer for a moment, and then turns it back on again. Sleep: Clicking on Sleep puts your computer in a low-power state, but doesn't turn it off. The main advantage is that it allows you to get back to work quickly, without having to wait for the computer to do a full reboot Working with Windows Whenever you open a program, file, or folder, it appears on your screen in a box or frame called a window (that's where the Windows operating system gets its name). Because windows are everywhere, it’s important to understand how to move them, change their size, or just make them go away. Parts of a window Page 24 Although the contents of every window are different, all windows share some things in common. For one thing, windows always appear on the desktop - the main work area of your screen. In addition, most windows have the same basic parts. Title bar. Displays the name of the document and program (or the folder name if you're working in a folder). Minimize, Maximize, and Close buttons.These buttons hide the window, enlarge it to fill the whole screen, and close it, respectively (more details on these shortly). Menu bar.Contains items that you can click to make choices in a program. Scroll bar.Let’s you scroll the contents of the window to see information that is currently out of view. Borders and corners. You can drag these with your mouse pointer to change the size of the window. Example: Open a notepad application and see the components Note: A dialog box is a special type of window that asks you a question, allows you to select options to perform a task, or provides you with information. You'll often see dialog boxes when a program or Windows needs a response from you before it can continue. Unlike regular windows, most dialog boxes can't be maximized, minimized, or resized. They can, however, be moved. Page 25 Working with file and folder (file management) 1. Selecting a single or multiple object  To select a single object, click on it once.  There are several ways to select Multiple files or folders.  To select a consecutive group of files or folders, click the first item, press and hold down the Shift key, and then click the last item.  To select Multiple files or folders that are near each other, drag the mouse pointer to create a selection around the outside of all the items that you want to include.  To select non-consecutive files or folders, press and hold down the Ctrl key, and then click each item that you want to select.  To select all of the files or folders in a window, on the toolbar, click Organize, and then click Select all. If you want to exclude one or more items from your selection, press and hold down the Ctrl key, and then click the items. Notes: After selecting files or folders, you can perform many common tasks, such as copying, deleting, renaming, printing, and compressing. Simply right-click the selected items, and then click the appropriate choice. 2. Rename  Click the file or folder to select it  Click the organize button on the toolbar, and then click Rename  With the name selected highlights, type a new name, or click to position the insertion point, and then edit the name.  Press Enter Notes: Right-click the file or folder you want to rename, click Rename, type a name, and then press Enter. You can also select the file, then press F2, type a name, and then press Enter. File names can be up to 255 characters. You can use spaces and underscores in names, but you can’t use the following characters: * : | ? “ \ or /. Remember the best way to keep your files organized is with a consistent naming convention. 3. Copying Page 26 When you copy an item, the original item remains in its original location plus you have the new copy  Open the location that contains the file you want to copy.  Right-click the file, and then click Copy.  Open the location where you want to store the copy  Right-click an empty space within the location, and then click Paste The copy of the original file is now stored in the new location. Notes:  Another way to copy and paste files is to use the keyboard shortcuts Ctrl+C (Copy) and Ctrl+V (Paste).  You can also press and hold the right-mouse button and then drag the file to the new location. When you release the mouse button, click Copy here. 4. Moving Cut or Moving a file (or folder) is different from copying it. Moving cuts, the item from its previous location and places it in a new location. Copying leaves the original item where it was and creates a copy of the item elsewhere. In other words, when you copy something you end up with two of it. When you move something, you only have the one thing.  Open the drive or folder containing the file or folder you want to move.  Select the files or folders you want to move.  Click the Organize button on the toolbar, and then click Cut  Display the destination folder where you want to move the files or folder.  Click the Organize button on the toolbar, and then click Paste.  Copy or Move a File or Folder Using Drag and Drop  Open the drive or folder containing the file or folder you want to copy or move.  Select the files or folders you want to copy or move.  In the Navigation pane, point to a folder list to display the expand and collapse arrows.  Click the arrows to display the destination folder, and then click the destination folder.  Right-click the selected files or folders, drag to the destination folder, and then click Copy Here or Move Here. Notes: To move the selected items, drag them to the destination folder. To copy the items, hold down the Ctrl key while you drag. Another way to copy and paste files is to use the keyboard shortcuts Ctrl+X (Cut) and Ctrl+V (Paste). Pay attention to pop-up messages that appear when dragging— you can use these to find out what will happen when you release the mouse button. Page 27  5. Create a Folder Steps  Open the drive or folder where you want to create a folder.  Click the New folder button on the toolbar.  With the New Folder name selected, type a new name.  Press Enter. Notes: Right-click a blank area on the desktop or in the folder window, point to New, and then click Folder. 6. Deleting Steps  Select the file or folder.  Click the Organize button and select Delete from the pull-down menu.  After you select delete a confirmation message appears. Notes:  You can also delete a file or folder by press right click on the item and then click delete or press Del buttons on the keyboard.  The easiest way to delete on the desktop by drag and drop it to recycle Bin.  When you delete a file or folder from your hard disk, it's not deleted right away. Instead, it's stored in the Recycle Bin until the Recycle Bin is emptied.  If you delete a file or folder from a network folder or from a USB flash drive, it might be permanently deleted rather than being stored in the Recycle Bin.  If a file can’t be deleted, it might be in use by a program that's currently running. Try closing the program or restarting your computer to fix the problem. For more information.  To permanently delete a file without first moving it to the Recycle Bin, select the file, and then press Shift + Delete.  When you delete a file, it's usually moved to the Recycle Bin so that you can restore the file later if necessary.  To permanently remove files from your computer and reclaim any hard disk space they were using, you need to delete the files from the Recycle Bin. You can delete individual files from the Recycle Bin or empty the entire Recycle Bin at once.  Open the Recycle Bin by double-clicking the Recycle Bin on the desktop. To permanently delete one file, click it, press Delete, and then click Yes. To delete all of the files, on the toolbar, click Empty the Recycle Bin, and then click Yes Page 28   You can empty the Recycle Bin without using Empty Recycle Bin opening it by right-clicking the Recycle Bin and then clicking Empty Recycle Bin.  To Restore item from recycle Bin, Open the Recycle Bin by double- clicking the Recycle Bin on the desktop. To restore a file, click it, and then, on the toolbar, click Restore this item. To restore all of the files, make sure that no files are selected, and then, on the toolbar, click Restore all items. The files will be restored to their original locations on your computer. Note Deleted files do not stay in the Recycle Bin indefinitely. By default, the deleted files in the Recycle Bin can occupy 10% of your hard disk space. When you’ve deleted enough files to exceed this 10%, the oldest files in the Recycle Bin are automatically and permanently deleted from your hard disk. PROGRAMMING LANGUAGES Programming languages are the mediums used by human beings to communicate their instruction to computers PROGRAMMING LANGUAGES are also classified as  Machine Languages  Low Level Languages  High Level Languages Examples of programming languages: FORTRAN, COBOL, PL/one, BASIC,FOCUS, NOMAD,PASCAL,C,C+, etc.... SYSTEM SOFTWARE Application Software Application software is a set of computer programs (instruction) that are developed to address the user needs to perform specific function or solve specific problems. Some of the major application software categories are discussed below:  Word Processing – such application are used for processing and manipulating text-based data, such as writing documents. o Example: Microsoft Word  Spreadsheet - such applications are built-in with various routines that are used for processing numerical data. Applications that fall in this category are often used in financial, statistical, mathematical problem solving. o Example: Microsoft Excel, SPSS, PeachTree  Data Management – These applications provide a structured system to manage data that enable to store, retrieve, and manipulate data. o Microsoft Access, Paradox, Oracle, Sybase Page 29   Desktop Publishing - these applications are similar to word processors providing a powerful sophisticated routines for creating publications, such as high quality newsletters, advertising and marketing materials. o Example: Microsoft Publisher, Quark Express  Graphics – such software are used in creating, storing, analysing, displaying, printing of charts, graphs, maps, design drawings. Examples of graphics applications are: o Presentation software o CAD (computer Aided Design) – such as AutoCAD  Multimedia – multimedia applications are used for processing audio, animation, video, graphics and images. 3 Human ware Information technology professional are responsible for acquiring, developing, maintain or operating the hardware and software associated with computers and communication networks. The following IT professionals have the highest profile: IT PROFESSIONAL DUTY Programmers use programming languages to create computer (software Engineer) and communications network software Systems Analysts work with users to determine the requirements an application must meet. As part of their job, they may specify the purchase of software package that gets the job done or order the development of custom software. Project Managers coordinate the development of a project and manage the team of programmer/analysts Network Specialists design, operate, and manage computer communications networks Trainers work with end-users, helping them to become comfortable and skilled in using hardware or software Computer Operators oversee the operations of computers in data centre sometimes called computer centres (facilities at which large and midrange computers systems are located). These systems are shared by many users who are interconnected with the system through communications links. Computer operators also perform support activities, such starting application, loading magnetic tape, and anything else that will ensure the smooth operation of computer facilities. Computer Engineer the IT professionals who design, develop and oversee the manufacturing of computer equipment Systems Engineers The IT professionals who install and maintain hardware. Page 30