ser is an agent, either a human agent (end-user) or software agent, who uses a computer or network service. Users are also widely characterized as the class of people that use a
system without the complete technical expertise required to understand the system fully. Computer users can be classified into the following categories based on the way they think about computers.
Application-oriented Users
The vast majority of computer users are application-oriented. They have training and experience exclusively with commercial software. They understand concepts peculiar to computers such as files, folders, saving, and deleting. They live in a WYSIWYG world; although they may be aware that what they see on the screen is not an entirely accurate representation of what the computer is actually doing, they are not interested in understanding hidden implementations. They have learned how to map their thinking onto the capabilities of the applications they regularly use, and they accept whatever limitations that thinking may impose. They are pragmatic, learning as much as they need to get their work done. A new problem requires a new piece of software. Spreadsheet
―programmers‖ fall into this category, as may some programmers who work primarily with application scripting tools such as Microsoft Visual Basic for Applications. Nearly all commercial
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software is targeted at this group of users, who can be considered
―computer-literate.‖
Goal-oriented users
The second largest group consists of goal-oriented users. These users focus exclusively on the goals they want to accomplish and neither understands nor cares about the software they use to accomplish those goals. This could be called the ―I just want to type a letter‖ group. They only see the final product. They do not care about, for example, the difference between a word processor document and a PDF image of that same document, so they do not understand why they can make textual edits to one and not the other. They could be described as ―computer-illiterate,‖ even if they work with computers on a regular basis. Many very intelligent people, scientists and scholars, fall into this category. They are frustrated by the limitations of the software they use because they do not understand the reasons for those limitations. Though they may use common terms such as ―files,‖ they typically map those concepts onto their real-world metaphorical analogues, resulting in confusion. (―Why can‘t I keep this picture in my email file?‖)
Original Computer Users
The third and smallest group of computer users ironically, the original computer users is comprised of hackers. Hackers are computer-oriented computer users. They have learned how to think like a computer, to understand the processes the computer goes through. They favor small tools (e.g. the command line, shell scripts) over large applications because they want to be in precise control of what the computer is doing at all times. They comfortably work with data in ―raw‖ formats such as text files. This does not necessarily mean they are tied down with minutiae of implementation; often they can work at much higher levels of abstraction than other users. Hackers tend to seek out the abstract
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patterns inherent in whatever end result they are working towards, then implement those patterns in the computer. A new problem rarely requires new tools, merely a new application of existing tools. They will create whatever new tools are needed to bring the computer up to the level of the problem, rather than trying to adapt the problem to fit the computer. On the other hand, their solutions tend to be brittle, with a lot of exposed complexity that makes them unsuitable for non-hacker users.
7.2 System Booting
When we start our Computer, there is an operation which is performed automatically by the Computer which is also called as Booting. In the Booting, System will check all the hardware‘s and Software‘s those are installed or Attached with the System and this will also load all the Files those are needed for running a system. In the Booting Process all the Files those are Stored into the ROM Chip will also be Loaded for Running the System. In the Booting Process the System will read all the information from the Files those are Stored into the ROM Chip and the ROM chip will read all the instructions those are Stored into these Files. After the Booting of the System this will automatically display all the information on the System. The Instructions those are necessary to Start the System will be read at the Time of Booting. There are two Types of Booting.
Cold Booting: when the System Starts from the Starting or from initial State Means when we Starts our System this is called a cold Booting. In the cold Booting the System will be started from its beginning State means first of all, the user will press the Power Button, then this will read all the instructions from the ROM and the Operating System will be automatically gets loaded into the System RAM.
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Warm Booting: The warm Booting is that in which System Automatically Starts when we are Running the System, For Example due to Light Fluctuation the system will Automatically Restarts So that in this Chances Damaging of system are more, and the System will not be start from its initial State So May Some Files will be Damaged because they are not Properly Stored into the System.
7.3 Occupational Health and Safety
Basic Description of Occupational health and safety Occupational health and safety is a cross-disciplinary area concerned with protecting the safety, health and welfare of people engaged in work or employment. The goal of all occupational health and safety programs is to foster a safe work environment. As a secondary effect, it may also protect co-workers, family members, employers, customers, suppliers, nearby communities, and other members of the public who are impacted by the workplace environment. It may involve interactions among many subject areas, including occupational medicine, occupational (or industrial) hygiene, public health, safety engineering, chemistry, health physics. Occupational health should aim at:
The promotion and maintenance of the highest degree of physical, mental and social well-being of workers in all occupations;
The prevention amongst workers of departures from health caused by their working conditions;
The protection of workers in their employment from risks resulting from factors adverse to health;
The placing and maintenance of the worker in an occupational environment adapted to his physiological and psychological capabilities;
These regulations are concerned with the working environment. They place a duty on employers to make sure that the workplace is
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safe and suitable for the tasks being carried out there, and that it does not present risks to employees and others.
7.3.2 Regulation For Maintaining Health and Safety
The regulations for maintaining health & safety in the working environment, includes:
maintenance of the workplace, equipment, devices and systems
ventilation
temperature in indoor workplaces
lighting
cleanliness and waste materials
room dimensions and space
work stations and seating
condition of floors and traffic routes
falls or falling objects
windows and transparent or translucent doors, gates and walls
windows, skylights and ventilators
ability to clean windows, etc. safely
doors and gates
escalators and moving walkways
sanitary conveniences
washing facilities
drinking water
accommodation for clothing
facilities for changing clothing
Facilities for rest and to eat meals.
7.3.3 Why Occupational Health and Safety
Some reason for occupation health and safety are;
Occupational health and safety promote health and safety procedures in organizations.
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Help to recognize hazards and measure health and safety risks, set suitable safety controls in place, and give recommendations on avoiding accidents to management and employees in an organizations.
An effective training program can reduce the number of injuries and deaths, property damage, legal liability, illnesses, workers’ compensation claims, and missed time from work.
Safety training classes help establish a safety culture in which employees themselves help promote proper safety procedures while on the job. It is important that new employees be properly trained and embraces the importance of workplace safety as it is easy for seasoned workers to negatively influence the new hires.
7.3.4 Safety and Health Hazards
The terminology used in OSH varies but generally speaking a hazard is something that can cause harm if not controlled. The outcome is the harm that results from an uncontrolled hazard. A risk is a combination of the probability that a particular outcome will occur and the severity of the harm involved. ―Hazard‖, ―risk‖, and
―outcome‖ are used in other fields to describe e.g. environmental damage, or damage to equipment. However, in the context of OSH,
―harm‖ generally describes the direct or indirect degradation, temporary or permanent, of the physical, mental, or social well- being of workers. For example, repetitively carrying out manual handling of heavy objects is a hazard. The outcome could be a musculoskeletal disorder (MSD) or an acute back or joint injury.
7.3.5 Nigerian Occupational Health and Safety Bill
The Bill to enact a law that would take care of the health and safety of industrial workers passed through second reading on the floor of the Senate on 25th February, 2009. The bill sponsored by Senator
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Chris Anyanwu which was committed to the senate committees on Labor, Health seeks amongst other things to ensure that employers of labor are properly protected.
Highlights of Nigerian Occupational Health and Safety Bill
To make further provisions for securing the safety, health and welfare of persons at work
To make provisions for protecting others against risks to safety or health in connection with the activities of persons at work
To establish the National Council for Occupational Safety and Health to create a general framework for the improvement of working conditions and the working environment
To prevent accidents and departures from health arising out of or in the course of work
To ensure the provision of occupational safety and health services to workers in all sectors of economic activity
The bill is also to establish the National Council for Occupational Safety and Health Hazards and for related issues with the following functions
To ensure employee safety and health in Nigeria by working with employers and employees to create better working environments
To act as a regulatory agency by issuing safety and health standards that is enforceable under Nigerian safety law.
7.4 Computer Health and Safety
Description Of Computer Health And Safety
The number of computers in the workplace has increased rapidly over the last few years and it is now quite normal for most staff in organizations to be exposed to computer usage. The Health and Safety at Work Act lays down legal standards for computer
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equipment and requires employers to take steps to minimize risks for all workers. Improving health and safety practice should be taken seriously, although it need not take much time or expense. Measures employers should take include:
Understanding the law – make sure someone in your organization has a health and safety brief covering all areas, not just computers.
Being aware of the health risks – the government officially recognizes some of the risks although there are some grey areas you’ll need to make up your own mind about.
Assessing the risks – using procedures set out in the law – be systematic and get help if you need it. Get a health and safety audit done by a competent organization if necessary.
Taking steps to minimize the risks – this may only involve taking simple measures.
Training all users to recognize the risks – if people aren’t aware of the dangers they can’t take adequate precautions to protect their health.
Taking users views seriously – if users feel there is something wrong there often is.
7.4.2 Risks within Computer Environment
The main risks associated with using computers include:
Musculoskeletal problems
Eye strain
Hint‘ Rashes and other skin complaints have also been reported, although it is thought these are caused by the dry atmosphere and static electricity associated with display units rather than by the display units themselves.
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Musculoskeletal problems
These can range from general aches and pains to more serious problems which include
Upper limb disorders such as repetitive strain injury (RSI) and carpal tunnel syndrome – by far the most important as it can quickly lead to permanent incapacity
Back and neck pain and discomfort
Tension stress headaches and related ailments
Causes of Musculoskeletal Problems
Maintaining an unnatural or unhealthy posture while using the computer
Inadequate lower back support
Sitting in the same position for an extended period of time
An ergonomically poor workstation set up
Eye Strain
Computer users can experience a number of symptoms related to vision as follow:
Visual fatigue
Blurred or double vision
Burning and watering eyes
Headaches and frequent changes in prescription glasses Computer work hasn’t been proven to cause permanent eye damage, but the temporary discomfort that may occur can reduce productivity, cause lost work time and reduce job satisfaction.
Causes of Eye Strain
Eye problems are usually the result of visual fatigue
Glare from bright windows or strong light sources
Light reflecting off the display screen
Poor display screen contrast
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7.4.3 Precaution to Prevent Risk Associated With Computer
Musculoskeletal Problems: General precautions to avoid musculoskeletal problems include:
Taking regular breaks from working at your computer – a few minutes at least once an hour
Alternating work tasks
Regular stretching to relax your body
Using equipment such as footrests, wrist rests and document holders if you need to
Keeping your mouse and keyboard at the same level
Avoiding gripping your mouse too tightly – hold the mouse lightly and click gently
Familiarize yourself with keyboard shortcuts for applications you regularly use (to avoid overusing the mouse)
It is also important to have your workstation set up correctly. Your workstation includes monitor, keyboard, mouse, seating, desk, and where appropriate, footrest (to enable you to put your feet flat if they would otherwise not reach the floor), wrist rest, and document holder.
Monitors should
Swivel, tilt and elevate – if not use an adjustable stand, books or blocks adjust the height
Be positioned so the top line of the monitor is no higher than your eyes or no lower than 20° below the horizon of your eyes or field of vision
Be at the same level and beside the document holder if you use one
Be between 18 to 24 inches away from your face
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Keyboards should
Be detachable and adjustable (with legs to adjust angle)
Allow your forearms to be parallel to the floor without raising your elbows
Allow your wrists to be in line with your forearms so your wrists does not need to be flexed up or down
Include enough space to rest your wrists or should include a padded detachable wrist rest (or you can use a separate gel wrist rest which should be at least 50 mm deep)
Be placed directly in front of the monitor and at the same height as the mouse, track ball or touch pad
Chairs should
Support the back – and have a vertically adjustable independent back rest that returns to its original position and has tilt adjustment to support the lower back
Allow chair height to be adjusted from a sitting position
Be adjusted so the back crease of the knee is slightly higher than the pan of the chair (use a suitable footrest where necessary)
Be supported by a five prong caster base
Have removable and adjustable armrests
Have a contoured seat with breathable fabric and rounded edges to distribute the weight and should be adjustable to allow the seat pan to tilt forward or back
Tables and desks should
Provide sufficient leg room and preferably be height adjustable
Have enough room to support the computer equipment and space for documents
Be at least 900 mm deep
Have rounded corners and edges
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Avoiding Eyestrain
Precautions that can be taken to avoid eyestrain include:
Exercising the eyes by periodically focusing on objects at varying distances
Blinking regularly
Keeping the air around you moist – for example using plants, open pans of water or a humidifier (spider plants are said to be particularly good for this and removing chemical vapors from the air)
Adjusting the screen height / seating so that when sitting comfortably your eyes are in line with the top of the monitor screen
Adjusting the brightness control on your monitor for comfort
Adjusting the contrast on your monitor to make the characters distinct from the background
Adjusting the refresh rate of your monitor to stop it flickering
Positioning monitors to avoid glare (e.g. not directly in front of windows)
Keeping your monitor the screen clean
Keeping the screen and document holder (if you use one) at the same distance from your eyes
Servicing, repairing or replacing monitors that flicker or have inadequate clarity
Regular eye testing – do this at least once every 2 years and more frequently if necessary – especially if you are experiencing eye problems related to using display equipment. Indicate the distance from your eyes to the monitor to your optician and talk to them regarding special lenses or the use of bifocals.
Computer software, or just software, is any set of machine- readable instructions (most often in the form of a computer program) that directs a computer’s processor to perform specific operations. Software is a general term. It can refer to all computer instructions in general or to any specific set of computer instructions. It is inclusive of both machine instructions (the binary code that the processor understands) and source code (more human- understandable instructions that must be rendered into machine code by compilers or interpreters before being executed). In most computer platforms, software can be grouped into a few broad
categories:
Figure 5a: Organization of Computer Software
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5.2 System Software
System software is a group of programs that contribute to the control and performance of the computer system. System software manages and supports the operations of computer systems and networks. They are usually provided by the computer manufacturers. System software is made up of systems management programs and systems development programs.
System Management Programs manage the hardware, software, network, and data resources of the computer system during its execution of the various information- processing jobs of users. Examples are operating systems, network management programs, database management systems, and system utilities.
System Development Programs help users develop information system programs and procedures and prepare user programs for computer processing. Examples are programming language translators and editors.
5.3 Operating Systems
An operating system is a collection of programs which takes over the operation of the computer to the extent of being able to allow a number of programs to be run on the computer without human interventions by an operator. Examples of operating systems on mainframe and minicomputers are IBM-OS/VS, IBM-OS/400 and ICL-VME. On microcomputers, examples include MS-DOS, WINDOWS and LINUX.
Functions of Operating Systems
An operating system (OS) performs five basic functions in the operation of a computer system, namely, providing a user interface, resource management, task management, file management, as well as utilities and support services.
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The User Interface: This is the part of the operating system that allows the user to communicate with it so that the user can load programs, access files, and accomplish other tasks. The main types of user interfaces are
Resource Management: An operating system uses a variety of resource management programs to manage the hardware and networking resources of a computer system, including its CPU, memory, secondary storage devices, telecommunications processors, and input/output peripherals. For example, memory management programs keep track of where data and programs are stored.
File Management: An operating system contains file management programs that control the creation, deletion, and access of files of data and programs. File management also involves keeping track of the physical location of files on magnetic disks and other secondary storage devices. So, operating system maintains directories of information about the location and characteristics of files stored on a computer systems secondary storage device.
Task Management: The task management programs of an operating system manage the accomplishment of the computing tasks of end-users. They give each task a slice of a CPU‘s time and interrupt the CPU operations to substitute other tasks. Task management may involve a multitasking capability where several computing tasks can occur at the same time. Multitasking may take the form of multiprogramming, where the CPU can process the tasks of several programs at the same time, or timesharing, where the computing tasks of several users can be processed at the same time.
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System Utilities: Utility programs are type of system management software that are marketed as separate programs or are included as part of an operating system. Utilities perform miscellaneous housekeeping and file conversion functions. Examples include data backup, data recovery, virus protection, data compression, and file defragmentation.
5.4 Utilities and Service Programs
These are systems programs that provide facilities for performing common tasks of routine nature. The main types include.
Sort is a program used to arrange records into a predetermined sequence by reference to a record key.
Editors are used at a terminal and provide facilities for the creation or amendment of programs.
File Copying is a program that copies data from one medium to another, for example, from diskettes to hard disk.
File Renaming is a program that changes the name of a file to another.
File Backup is a program that copies data or file from one medium to another for security purposes.
Disk Formatting is a program that prepares a disk or diskette for the purpose of receiving and storing data..
Dump is a program that is used to copy the contents of the main storage onto an output medium such as paper.
File maintenance is a program that carries out the process of insertion and deletion of records in any file. It can also make amendments to standing data in records.
Tracing and Debugging is used in conjunction with the testing of application programs on the computer. Tracing involves dumping to locate errors. Debugging is the process of eliminating errors from a program.
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5.5 Programming Languages
A programming language describes the way in which the instructions that make up a computer program are written. The three basic types of programming languages are machine language, assembly language and high-level language.
5.5.1 Machine Languages
A machine language is a programming language composed of numeric instructions. It is made up of strings of binary digits specific to a particular make and model of computer. When programming in machine language, an appropriate set of storage locations must be allocated for both the program and the data before any actual instructions can be written. The interpretation of a machine language program is a direct function of the computer hardware circuitry.
Advantages of Machine Languages
They are very flexible. They allow programmers to make efficient use of the computer‘s capabilities.
The concepts of machine language programming involve simply transferring data into and out of the accumulator.
Disadvantages of Machine Languages
Machine language programming is very detailed; therefore, an actual program can be quite complicated.
Tedious bookkeeping is involved in writing machine language programs.
Machine language programs are difficult to correct for errors and difficult to alter.
Every computer model has its own machine language; hence machine language programs are machine dependent.
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5.5.2 Assembly Language
An assembly language is a programming language made up of operation mnemonics and symbolic data locations. The assembly language programmer makes use of instruction mnemonics and symbolic names of addresses rather than work with operation codes and operand addresses.
Advantages of Assembly Language
The task of learning and writing the language is easier than with machine language.
Macroinstructions enable one instruction to be translated into several machine language instructions.
Assembly languages can be used for programming closed subroutines.
Disadvantages of Assembly Language
Assembly languages are more difficult to learn than high- level languages.
An assembly language program is more difficult to modify than corresponding high-level language program.
An assembly language is machine dependent.
5.5.3 High-Level Languages
A high-level computer language is a programming language composed of instructions written in English words (for business applications) or in mathematical notations (for scientific applications).The two main purposes of a high-level language are:
To improve the productivity of programmers because high- level languages are relatively easier to learn and a statement written in a high-level language would produce several machine code instructions.
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To enable programs to be used on different types of computers without the need to rewrite the programs completely.
Advantages of High-Level Languages
Instructions are more like English (for business applications) or more like mathematical notations (for scientific applications), so the languages are easier to learn, easier to write and easier to understand.
They are developed for use on more than one type of computer. That is, they are machine independent.
Programs written in a high-level language are easier to modify and to test.
Programmers trained in the use of a high-level language do not need to learn an entirely new language to work on a new computer.
Programs can be written by persons not possessing a detailed knowledge of computers because high-level languages are problem-oriented.
Disadvantages of High-Level Languages
The fact that high-level languages can be used for different makes of computers does not allow them to take advantage of specific facilities on individual computers.
Programs written in high-level languages are unlikely to be as efficient, in terms of processing speed and the use of internal storage space, as programs written in machine language or in assembly language.
5.6 Translators
A translator is a systems program that converts statements written in one programming language into statements in the computer language. The statements in a programming language are called
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source program. The statements in the computer language are called object program. The three types of translators are Assemblers, Compilers and Interpreters.
5.6.1 Assembler
An assembler (or a symbolic assembly program) is a program specially developed by the computer manufacturer to assist the programmer in the preparation of machine-code programs from programs written in symbolic language.
5.6.2 Compiler
A compiler is a program specially written by the computer manufacturer for the purpose of translating a program written in high level language into machine language.
5.6.3 Interpreter
The interpreter is used to translate high-level language programs. It deals with the source program one instruction at a time, completely translating and executing each instruction before it goes on to the next.
The advantage of the Interpreter over a compiler is that it is suitable for interactive work, where the programmer wishes to modify or test the program on-line as it is being developed.
Applications Software & Application Programs Applications software is a group of programs that are developed to solve particular problems. They directly provide the processing that users want to have performed. They may be produced by the computer manufacturer or supplier, a software house, or the computer user. They are of two types, application programs and application packages.
Application programs are mostly written by the users to carry out a task, e.g. payroll programs; hence they are also called user programs or tailor-made programs.
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Application packages are ready-made generalised programs with associated documentations for solving business and other problems.
Advantages of Application Software
The user gets a well-tried and tested program.
Implementation is quicker and possibly cheaper.
Systems design, programming and systems testing are minimised.
Systems documentation is provided with the packages.
Efficiency in terms of speed, storage requirements and accuracy.
Portability from the existing computer system to another.
Disadvantages of Application Packages
It may be inefficient due to the inclusion of irrelevant features.
It might be used even when it is not completely suitable to the particular application.
The user is dependent on the supplier for the maintenance of the package.
No immediate help on site when a serious problem occurs.
May not be updated in line with legislation, e.g. VAT rates.
5.8 Application Software Selection
There are various considerations before one select application software for his or her business organization or individual personal uses. Some of the considerations are described as follows.
Comprehensiveness. The package must satisfy user‘s requirements.
Cost. It should be affordable to the user.
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Reliability. The package should have been used by other organisations for some time with considerable degree of success.
Flexibility. It should be fairly easy to be amended, modified and upgraded.
Portability. The package should be suitable for use with any computer system acquired in the future by the user.
Interfacing. The package should link up conveniently with existing systems and routines.
Peripherals. The input and output hardware devices required by the package should be compatible with the user‘s existing devices.
Storage. The package should be able to be accommodated within the main storage and backing storage existing on the user‘s system.
Documentation. It must be well documented. The procedures for input, processing and output should be clearly documented.
Timing. The time required to process a particular application, such as payroll, should be compared on a number of similar packages.
5.9 Software Suites
A software suite consists of most widely used productivity packages bundled together. Examples are Microsoft Office, Lotus Smart Suite and Corel Word Perfect Office. Each suite typically integrates software packages for word processing, spreadsheets, presentation graphics, database management and personal information management. Each suite may contain other programs such as programs for Internet access and web publishing.
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Advantages of Software Suite
It costs a lot less than the total cost of buying its individual packages separately.
All programs use a similar graphical user interface (GUI) of icons, tool and status bars, menus, and so on, which gives them the same look and feel, and makes them easier to learn and use.
All programs share common tools such as spell checkers and help wizards to increase their efficiency.
The programs are designed to work together seamlessly, and import each other‘s files easily, no matter which program is in use at the time. This makes them more efficient and easier to use than using a variety of individual package versions.
Disadvantages of Software Suite
Many software suite features are never used by most end users.
A desktop computer before is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware.
The figure below shows the most common hardware in a desktop computer system. Your system may look a little different, but it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.
Figure 4a: The Computer System
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The computer system components parts were described in chapter 2 of this book and almost all the components described are parts of computer hardware. In this chapter the computer hardware will be describe based on the computer hardware configuration which include both the directly visible and invisible hardware. This hardware configuration is as given in figure 4b below.
Figure 4b. Computer Hardware Configuration
Note: Computer Hardware can be divided basically into two; the CPU and Peripherals. CPU is made up of control unit, Arithmetic
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and logic unit and Main memory. While the peripheral is made up of Input devices, Output devices and Backing storage.
The components of computer hardware based on the diagram in figure 4b are the CPU and Peripherals (input and output units). Some of the peripherals were described in chapter two of this book.
4.2 Central Processing Unit
This is an integral part of system unit of computer system that made up of other components like; the main storage, the control unit and the arithmetic/logic unit.
Main Storage
The Main Storage contains two types of memory chips, named the Random-Access Memory (RAM) and Read-Only Memory (ROM). RAM is a memory that has the same access time for all locations. It is used to store data and program temporarily whenever they are needed in main memory. It is constantly being re-used for different data items or programs as required. Static RAM holds its memory so long as there is a power supply. Dynamic Ram (DRAM) has to be refreshed by reading and rewriting the contents very frequently. RAM is volatile, that is, the con-tents of RAM are lost when the power supply is switched off. ROM (integrated circuit) is used to store vital data and programs which need to be held within the main memory at all times. The contents of ROM are permanently set during the manufacture of the computer.
However, there are other ways of putting programs and data into ROM. Programmable Read-Only Memory (PROM) is a type of ROM that is manufactured as an empty storage array and is later permanently programmed by the user. Erasable PROM (EPROM) is a type of PROM whose data can be erased by a special process so new data can be written as if it were a new PROM. Arithmetic/Logic Unit (ALU)
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The Arithmetic/Logic Unit (ALU) consists of adder/subtractor, electronic circuit and working registers to which operands may be transferred during an operation. The ALU performs the
Arithmetic Operations
Data Handling Operations
Logical Functions.
The data to be processed are taken from main storage, stored in the working registers, processed and the results placed back in the main storage.
Control Unit
The Control Unit examines the individual instructions in the users‘ program one by one, interprets each instruction and causes the various circuits to be activated to perform the functions specified. Some of the functions of the control unit are:
It co-ordinates the various parts of the computer system to form a composite integrated data processing system.
It controls the transfer of data between and within the working stores as required by the program.
It controls input/output. Once the program controller has initiated a read/write operation, the control unit continues to monitor the operation to ensure that it is satisfactorily completed.
In time-sharing or on-line systems, the control unit co- ordinates the several concurrent peripheral operations while data is processed internally within the CPU.
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4.3 Peripherals Input & Output Devices
4.3.1 Input Device
Computer Input is the process of transferring data from computer- sensible media into the main storage of the computer. The equipment which converts data been captured on a source documents into machine sensible form is called an input device. The following terms are related to inputting data into computer.
Data Capture is the term used to describe the process of collecting data in machine sensible form at its source.
Data Collection is the term used to describe the process of recording the data on source document and subsequently converting it into machine sensible form for input to the computer.
Data Conversion is the process of transforming the data on source documents into machine sensible form before carrying out the input operation.
Type of Input Device
Direct Input Devices allow data to be input into the computer without any need for data conversion. Examples are: keyboard terminals, mouse, trackballs, scanners, joystick, bar-code readers, touch screens, OCR, OMR and MICR equipment.
Indirect Input Devices accept data from source documents and convert it into computer-sensible form for subsequent input into the computer. Examples are: magnetic tape, magnetic disk, compact disk and diskette drives.
Input devices can also be classified as manual or automated. Manual input devices include keyboard, mouse, trackball, joystick, bar-code readers, scanners, and touch screens. Automated input
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devices include MICR, OCR, OMR, magnetic stripe and smart cards.
Computer keyboard
A keyboard is used mainly for typing text into your computer. Like the keyboard on a typewriter, it has keys for letters and numbers, but it also has special keys like:
The function keys, found on the top row, perform different functions depending on where they are used.
The numeric keypad, located on the right side of most keyboards, allows you to enter numbers quickly.
The navigation keys, such as the arrow keys, allow you to move your position within a document or webpage.
Some modern keyboards come with “hot keys” or buttons that give you quick and one-press access to programs, files, or commands. Other models have volume controls, scroll wheels, zoom wheels, and other gadgets. For details about these features, check the information that came with your keyboard or computer, or go to the manufacturer’s website.
Figure 4c. Modern computer keyboard
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Three odd keys
So far, we’ve discussed almost every key you’re likely to use. But for the truly inquisitive, let’s explore the three most mysterious keys on the keyboard: PRINT SCREEN, SCROLL LOCK, and PAUSE/BREAK.
Print Screen (or PRT SCN)
A long time ago, this key actually did what it says—it sent the current screen of text to your printer. Nowadays, pressing PRINT SCREEN captures an image of your entire screen (a “screen shot”) and copies it to the Clipboard in your computer’s memory. From there you can paste it (CTRL+V) into Microsoft Paint or another program and, if you want, print it from that program. More obscure is SYS RQ, which shares the key with PRINT SCREEN on some keyboards. Historically, SYS RQ was designed to be a “system request,” but this command is not enabled in Windows.
Scroll Lock (or SCR LK)
In most programs, pressing SCROLL LOCK has no effect. In a few programs, pressing SCROLL LOCK changes the behavior of the arrow keys and the PAGE UP and PAGE DOWN keys; pressing these keys causes the document to scroll without changing the position of the cursor or selection. Your keyboard might have a light indicating whether SCROLL LOCK is on.
Pause/Break
This key is rarely used. In some older programs, pressing this key pauses the program or, in combination with CTRL, stops it from running.
Electronic Mouse
A mouse is a small device used to point to and select items on your computer screen. Although mice come in many shapes, the typical
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mouse does look a bit like an actual mouse. It’s small, oblong, and connected to the system unit by a long wire that resembles a tail.
Some newer mice are wireless. When you move the mouse with your hand, a pointer on your screen moves in the same direction. (The pointer’s appearance might change depending on where it’s positioned on your screen.) When you want to select an item, you point to the item and then click (press and release) the primary button. Pointing and clicking with your mouse is the main way to interact with your computer.
A mouse typically has two buttons: a primary button (usually the left button) and a secondary button (usually the right button). The primary button is the one you will use most often. Most mice also include a scroll wheel between the buttons to help you scroll through documents and webpages more easily. On some mice, the scroll wheel can be pressed to act as a third button. Advanced mice might have additional buttons that can perform other functions.
Figure 4d. Parts of a mouse
Holding and Moving the Mouse
Place your mouse beside your keyboard on a clean, smooth surface, such as a mouse pad. Hold the mouse gently with your index finger resting on the primary button and your thumb resting on the side. To move the mouse, slide it slowly in any direction. Don’t twist it; keep
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the front of the mouse aimed away from you. As you move the mouse, a pointer on your screen moves in the same direction. If you run out of room to move your mouse on your desk or mouse pad, just pick up the mouse and bring it back closer to you. Hold the mouse lightly, keeping your wrist straight. Figure 4d illustrate the explanation given.
Figure 4d. Mouse holding technique
Pointing, clicking, and dragging: Pointing to an item on the screen means moving your mouse so the pointer appears to be touching the item. When you point to something, a small box often appears that describes the item. For example, when you point to the Recycle Bin on the desktop, a box appears with this information: “Contains the files and folders that you have deleted.”
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Figure 4e.Pointing to an object to reveals a descriptive message about it
The pointer can change depending on what you’re pointing to. For example, when you point to a link in your web browser, the pointer changes from an arrow to a hand with a pointing finger . Most mouse actions combine pointing with pressing one of the mouse buttons. There are four basic ways to use your mouse buttons: clicking, double-clicking, right-clicking, and dragging.
Clicking (single-clicking): To click an item, point to the item on the screen, and then press and release the primary button (usually the left button). Clicking is most often used to select (mark) an item or open a menu. This is sometimes called single-clicking or left-clicking.
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Double-clicking: To double-click an item, point to the item on the screen, and then click twice quickly. If the two clicks are spaced too far apart, they might be interpreted as two individual clicks rather than as one double-click.
Double-clicking is most often used to open items on your desktop. For example, you can start a program or open a folder by double-clicking its icon on the desktop.
Right-clicking: To right-click an item, point to the item on the screen, and then press and release the secondary button (usually the right button). Right-clicking an item usually displays a list of things you can do with the item. For example, when you right-click the Recycle Bin on your desktop, Windows displays a menu allowing you to open it, empty it, delete it, or see its properties. If you’re ever unsure of what to do with something, right-click it. Right-clicking the Recycle Bin opens a menu of related commands
Figure 4f. Right clicking recycle bin
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Dragging: You can move items around your screen by dragging them. To drag an object, point to the object on the screen, press and hold the primary button, move the object to a new location, and then release the primary button. Dragging (sometimes called dragging and dropping) is most often used to move files and folders to a different location and to move windows and icons around on your screen.
Using the Scroll Wheel
If your mouse has a scroll wheel, you can use it to scroll through documents and webpages. To scroll down, roll the wheel backward (toward you). To scroll up, roll the wheel forward (away from you).
Customizing Your Mouse
You can change your mouse settings to suit your personal preferences. For example, you can change how fast your mouse pointer moves around the screen, or change the pointer’s appearance. If you’re left-handed, you can switch the primary button to be the right button.
Trackballs
A trackball is like a mouse turned upside down. It is a stationary device related to the mouse. It has a roller ball with only its top exposed outside its case. The cursor on the screen is moved whenever the roller ball is turned. Pressing buttons on the trackball activates various activities represented by the icon selected.
(a) A mouse
(b) A trackball
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Touch Screens
Touch screen is a special screen that is able to detect the position on the screen that a user‘s finger is touching or pointing at. A standard computer screen is covered by two very thin pieces of plastic. Embedded into the plastic is a fine wire and that is linked to the computer. When someone touches the grid, the computer can deduce exactly where the touch is made.
Joysticks
Joysticks are used more on video games than with PCs. A joystick has a short vertical handle that can be tilted forwards and backwards, left and right. A joystick allows the user to point to objects on the screen in the same way as a mouse, but it is more convenient for following a moving target. It may have one or more buttons on it.
Light Pen
A light pen allows the user to point the pen at different parts of a screen to select an option or draw a graphic, so it is like very accurate Touch screens. The use of light pens is quite rare.
Optical Scanners
Optical scanning devices read text or graphics and convert them into digital input for the computer. Thus, optical scanning enables the direct entry of data from source documents into a computer system. Optical scanners employ photoelectric devices to scan the characters being read. Reflected light patterns of the data are converted into electronic impulses that are then accepted as input into the computer system. Optical Character Recognition (OCR) is a form of optical scanning.
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Voice Recognition
Voice recognition systems analyse and classify speech or vocal tract patterns and convert them into digital codes for entry into a computer system. Voice recognition systems with large vocabularies require training the computer to recognise your voice in order to achieve a high degree of accuracy
Magnetic Stripe
Swipe and credit cards have black iron oxide coating of magnetic stripe on the reverse side, and it is this that the computer recognises. The black stripe holds information, such as customer account numbers, that can be accessed only by a special magnetic reading device. The reading device converts the information into computer usable form, for example, at the automated teller machines found at banks and at credit card authorization terminals.
Smart Cards
Smart Cards embed a microprocessor chip and several kilobytes of memory into debit, credit, and other cards. Smart debit cards enable the user to store a cash balance on the card and electronically transfer some of it to others to pay for small items and services. The balance on the card can be replenished in automated teller machines (ATMs) or other terminals. Smart cards are widely used to make payments in parking meters, vending machines, pay telephones, and retail stores.
Digital Cameras
Digital still cameras and digital video cameras (digital camcorders) enable the user to shoot, store, and download still photos or full motion video with audio into a PC. Then image-editing software can be used to edit and enhance the digitised images and include them in newsletters, reports, multimedia presentations, and web pages.
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Optical Character Readers
Optical character readers (OCR) are machines capable of reading printed documents directly into the computer by recognising the shape of the different characters. Reading of documents prepared in optical characters is accomplished by the use of a scanning device that reflects light from the character on to a lens where it is focused on a photoelectric cell. The cell produces a variable electric current that is unique for each character read. This process is termed optical character recognition.
Optical Mark Readers
Optical mark readers (OMR) are machines that use an artificial light source to scan marks made on OMR documents in order to determine their values. Marking is done in small horizontal shape on documents with black media such as a soft pencil. On OMR documents, predetermined positions are given certain values. The optical reader converts the mark in a position to the appropriate value. This is termed optical mark recognition (OMR).
Magnetic Ink Character Readers
Magnetic ink character readers (MICR) are machines capable of reading magnetic ink characters on MICR documents and passing the data into a computer. A MICR document has human-readable characters printed in the normal way with the use of a specially designed font but using a ferrous-based ink that is capable of magnetization.
Magnetic Ink Character Recognition (MICR) technology is employed by the computer systems of the banking industry to read cheques magnetically.
On-Line Input
This entails data being transmitted directly to the computer by the use of terminals sited at a distance from the computer and linked to
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it by communication arrangements. The computers‘ response is transmitted back to the terminal.
Bar Coding
Bar coding is the representation of code numbers or other data by bars or lines printed or embossed on a data carrier. The data carrier may be a tag, ticket, label, plastic card or a packet/can holding goods.
Universal Product Code
The Universal Product Code (UPC) system was introduced by the USA to cover the complete range of grocery products. Each product is given a unique 10-digit code that is represented in bar code form on every packet or other type of container or on labels. The bars are in pairs, each of which represents a digit according to their spacing and thickness. Certain symbols are also represented including those to indicate the start and finish of the bar coding. The European equivalent of UPC is the European Article Number (EAN).
Bar Code Readers
A bar code reader functions as follows: The bar code is scanned by a laser, which measures the thickness of the lines and the distance between them to decipher the code. Once read, the information can be transmitted to a computer. These hardware devices are often used for point-of-sale input systems in supermarkets and other outlets.
Output Devices
Computer output is the process of transferring data and information from the main storage of the computer onto a human-sensible medium or a machine-sensible medium. The principal methods of producing computer output are:
Displayed output on a VDU screen
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Printed output on paper
Computer-sensible output on a magnetic medium
Computer output on microform
Plotters
Sound output
Video Output
Video monitors use cathode ray tubes (CRT) technology similar to the picture tubes used in home TV sets. The clarity of the video display depends on the type of video monitor and the graphic circuit board installed in the computer. The information displayed on the screen is often referred to as soft copy. Monitors can be monochrome or colour. Monochrome monitors give a display of varying intensity on a single colour, for example, white on black background or orange/green on dark background. Colour monitors give a display with a range of colours determined by the colour circuitry in the monitor and the computer.
Printers/ Plotters
A printer is a mechanical device used for producing human-readable information on paper. A printer is connected to a computer for the sole purpose of transferring the information from the computer to paper or other media. The version printed out on paper is often referred to as hard copy. The three main categories of computer printers are line printers, serial/character printers and laser printers. A plotter contains a pen that draws lines on paper. Plotters are devices used for producing hard copies of complex graphics outputs in the form of graphs, charts, histograms and diagrams. These devices are much better than ordinary printers at handling diagrams. The technique has a wide range of use in fields such as scientific research, engineering and management information systems. They are commonly used for such tasks as producing technical drawings and road/rail networks.
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Magnetically Encoded Output
Computer output, in coded form, are written onto a magnetic medium usually for the purpose of storing updated records. The magnetic media used for the purpose include diskette, compact disk, magnetic tape, and magnetic disks.
Sound Output
A sound output device reproduces previously recorded and stored sounds. Sound output devices are the output equivalent of sound input devices. Sound output devices simply convey pre-recorded information in audio form. Speech synthesis is the production of sounds resembling human speech by electronic methods. A speech synthesis output device creates speech output from text. Speech synthesis output devices are the flipside of automatic speech recognition input devices. Speech synthesis devices convey information in audio form.
Backing Storage
Backing storage is an extension to a computer‘s internal storage. It is used for the off-line mass storage of programs, data and files that are not currently being used for processing. The types of common backing storage in use are magnetic tape, magnetic disk, compact disk, USB flash drive and floppy disk.
Magnetic Tapes
The magnetic tape consists of a strip of plastic tape coated with a magnetic material deposited in grains, each of which may be magnetized in one of two directions. A tape is held on a reel. A tape drive is used for writing data onto magnetic tape from the processor and for reading data from magnetic tape into the processor. The reading/writing operations are accomplished by a pair of read/write heads.
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Advantages of Magnetic Tape
It is relatively inexpensive, compared to the magnetic disk.
It has a large data storage capacity.
It is capable of transferring data to and from the main storage of the computer at very high speed.
Transaction data can be recorded directly onto the magnetic tape by means of magnetic tape encoding machines.
Old data may be erased and the tape used repeatedly.
Disadvantages Of Magnetic Tape
It is only possible to access records serially.
Data can be accidentally erased or overwritten.
It is not possible to read the records on tape visually.
Updated information cannot be written back to the same location on the same tape.
Input data must be sorted into the sequence of the master file before updating can start.
Stringent environment control is necessary in order to eliminate dust and static electricity in the atmosphere.
Magnetic Disks
A magnetic disk or hard disk is a flat circular device, which is similar to a long-playing phonograph record. It is made of metal and each of the recording surfaces is coated with a thin layer of magnetisable iron oxide. Usually, six disks are held on a common axis, one above the other, to form a disk pack. A disk pack is mounted on a disk drive mechanism. The disk drive is used for writing data onto magnetic disk from the processor and reading data from magnetic disk into the processor. The reading/writing operations are accomplished by using a pair of read/write heads placed next to each recording surface.
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Advantages of Magnetic Disk
A pack of disks has very high storage capacity.
Data on tracks may be overwritten with new data.
Disks are ideal for storing subroutines, tables and rates.
Disks may be used for real-time remote enquiry systems.
The speed of data transfer from the processor and to the processor is very high.
Data can be input onto a disk without the need for sorting.
Any item of data can be directly addressed, depending upon the method of the file organisation used.
Disadvantages of Magnetic Disk
Disk storage devices are more expensive than many other storage media.
Data may be accidentally erased or overwritten.
It is more complex to program disk operations than for magnetic tape.
Disk operations involve the locating of overflow records.
USB Flash Drive
A USB flash drive is a data storage device that includes flash memory with an integrated Universal Serial Bus (USB) interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disc. Most weigh less than 30 grams (1.1 oz). As of January 2013, drives of up to 512 gigabytes (GB) were available. A one-terabyte (TB) drive was unveiled at the 2013 Consumer Electronics Show and became available later that year. USB flash drives are often used for the same purposes for which floppy disks or CDs were used, i.e., for storage, back-up and transfer of computer files.
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Advantages of USB Flash Drive
They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts
Nothing epitomizes modern life better than the computer. For better or worse, computers have infiltrated every aspect of our society. Today computers do much more than simply compute: supermarket scanners calculate our grocery bill while keeping store inventory; computerized telephone
switching centers play traffic cop to millions of calls and keep lines of communication untangled; and automatic teller machines (ATM) let us conduct banking transactions from virtually anywhere in the world. But where did all this technology come from and where is it heading to? To fully understand and appreciate the impact computers have on our lives and promises they hold for the future, it is important to understand their evolution. Some of the events that lead to the evolution of computer are described as follows.
Early Computing Machines and Inventors
The abacus was emerged about 5,000 years ago in Asia Minor and is still in use today, may be considered the first computer. This device allows users to make computations using a system of sliding beads arranged on a rack. Early merchants used the abacus to keep trading transactions. But as the use of paper and pencil spread, particularly in Europe, the abacus lost its importance. It took nearly 12 centuries, however, for the next significant advance in computing devices to emerge. In 1642, Blaise Pascal (1623-1662), the 18-year-
old son of a French tax collector, invented what he called a numerical wheel calculator to help his father with his duties. This brass rectangular box, also called a Pascaline, used eight movable dials to add sums up to eight figures long. Pascal’s device used a base of ten to accomplish this. For example, as one dial moved ten notches, or one complete revolution, it moved the next dial – which represented the ten’s column – one place. When the ten’s dial moved one revolution, the dial representing the hundred’s place moved one notch and so on. The drawback to the Pascaline, of course, was its limitation to addition.
Figure 3a. Abacus Device
Figure 3b. Pascaline
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In 1694, a German mathematician and philosopher, Gottfried Wilhem von Leibniz (1646-1716), improved the Pascaline by creating a machine that could also multiply. Like its predecessor, Leibniz’s mechanical multiplier worked by a system of gears and dials. Partly by studying Pascal’s original notes and drawings, Leibniz was able to refine his machine. The centerpiece of the machine was its stepped-drum gear design, which offered an elongated version of the simple flat gear. It wasn’t until 1820, however, that mechanical calculators gained widespread use. Charles Xavier Thomas de Colmar, a Frenchman, invented a machine that could perform the four basic arithmetic functions. Colmar’s mechanical calculator, the arithometer, presented a more practical approach to computing because it could add, subtract, multiply and divide. With its enhanced versatility, the arithometer was widely used up until the First World War. Although later inventors refined Colmar’s calculator, together with fellow inventors Pascal and Leibniz, he helped define the age of mechanical computation.
Figure 3c. Leibniz Machine
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The real beginnings of computers as we know them today, however, lay with an English mathematics professor, Charles Babbage (1791- 1871). Frustrated at the many errors he found while examining calculations for the Royal Astronomical Society, Babbage declared, “I wish to God these calculations had been performed by steam!” With those words, the automation of computers had begun. By 1812, Babbage noticed a natural harmony between machines and mathematics: machines were best at performing tasks repeatedly without mistake; while mathematics, particularly the production of mathematics tables, often required the simple repetition of steps. The problem centered on applying the ability of machines to the needs of mathematics. Babbage’s first attempt at solving this problem was in 1822 when he proposed a machine to perform differential equations, called a Difference Engine. Powered by steam and large as a locomotive, the machine would have a stored program and could perform calculations and print the results automatically. After working on the Difference Engine for 10 years, Babbage was suddenly inspired to begin work on the first general-purpose computer, which he called the Analytical Engine. Babbage’s assistant, Augusta Ada King, Countess of Lovelace (1815-1842) and daughter of English poet Lord Byron, was instrumental in the machine’s design. One of the few people who understood the Engine’s design as well as Babbage, she helped revise plans, secure funding from the British government, and communicate the specifics of the Analytical Engine to the public. Also, Lady Lovelace’s fine understanding of the machine allowed her to create the instruction routines to be fed into the computer, making her the first female computer programmer. In the 1980’s, the U.S. Defense Department named a programming language ADA in her honor.
Figure 3d. Babbage Machine
Babbage’s steam-powered Engine, although ultimately never constructed, may seem primitive by today’s standards. However, it outlined the basic elements of a modern general purpose computer and was a breakthrough concept. Consisting of over 50,000 components, the basic design of the Analytical Engine included input devices in the form of perforated cards containing operating instructions and a “store” for memory of 1,000 numbers of up to 50 decimal digits long. It also contained a “mill” with a control unit that allowed processing instructions in any sequence, and output devices to produce printed results. Babbage borrowed the idea of punch cards to encode the machine’s instructions from the Jacquard loom. The loom, produced in 1820 and named after its inventor, Joseph- Marie Jacquard, used punched boards that controlled the patterns to be woven.
Figure 3e. Hollerith Machine
In 1889, an American inventor, Herman Hollerith (1860-1929), also applied the Jacquard loom concept to computing. His first task was to find a faster way to compute the U.S. census. The previous census in 1880 had taken nearly seven years to count and with an expanding population, the bureau feared it would take 10 years to count the latest census. Unlike Babbage’s idea of using perforated cards to instruct the machine, Hollerith’s method used cards to store data information which he fed into a machine that compiled the results mechanically. Each punch on a card represented one number, and combinations of two punches represented one letter. As many as 80 variables could be stored on a single card. Instead of ten years, census takers compiled their results in just six weeks with Hollerith’s machine. In addition to their speed, the punch cards served as a storage method for data and they helped reduce computational errors. Hollerith brought his punch card reader into the business world, founding Tabulating Machine Company in 1896, later to become International Business Machines (IBM) in 1924 after a series of mergers. Other companies such as Remington Rand and Burroghs also manufactured punch readers for business use. Both
Businesses and the government used punch cards for data processing until the 1960’s.
In the ensuing years, several engineers made other significant advances. Vannevar Bush (1890-1974) developed a calculator for solving differential equations in 1931. The machine could solve complex differential equations that had long left scientists and mathematicians baffled. The machine was cumbersome because hundreds of gears and shafts were required to represent numbers and their various relationships to each other. To eliminate this bulkiness, John V. Atanasoff (1903), a professor at Iowa State College (now called Iowa State University) and his graduate student, Clifford Berry, envisioned an all-electronic computer that applied Boolean algebra to computer circuitry. This approach was based on the mid- 19th century work of George Boole (1815-1864) who clarified the binary system of algebra, which stated that any mathematical equations could be stated simply as either true or false. By extending this concept to electronic circuits in the form of on or off, Atanasoff and Berry had developed the first all-electronic computer by 1940. Their project, however, lost its funding and their work was overshadowed by similar developments by other scientists.
3.2 Personal Computers History and Development
The personal computer (PC) has revolutionized business and personal activities and even the way people talk and think; however, its development has been less of a revolution than an evolution and convergence of three critical elements – thought, hardware, and software. Although the PC traces its lineage to the mainframe and minicomputers of the 1950s and 1960s, the conventional thought that was prevalent during the first thirty years of the computer age saw no value in a small computer that could be used by individuals. A PC is a microcomputer, so named because it is smaller than a minicomputer, which in turn is smaller than a mainframe computer. While early mainframes and their peripheral devices often took
the floor space of a house, minicomputers are about the size of a refrigerator and stove. The microcomputer, whose modern development traces back to the early 1970s, and fits on a desk, from the start, the creation of the computer was centered on the concept that a single unit would be used to perform complex calculations with greater speed and accuracy than humans could achieve. On December 23, 1947, one of the most far-reaching technologies of the 20th Century was developed at Bell Laboratories by John Bardeen, Walter Brattain, and William Shockley – the transistor. But the transistor wasn’t available to U.S. manufacturers until 1956, when a seven year-old antitrust law suit against AT&T, the owners of Bell Labs, was settled. The judgment required that AT&T give away licenses to manufacture the transistor to American companies. Following this decision, the transistor was used to replace thousands of vacuum tubes in computers and began the miniaturization of electronics. Because it drastically reduced the size and heat considerations of the large vacuum tubes, the transistor enabled the computer to become a viable tool for business and government.
3.3 The Computer Mystique
From the beginning, computers baffled the populous with their capability. In corporate and government offices and on university campuses, information processing departments sprouted up to serve the computer. The IBM 701, which was introduced in 1952 as a business computer, was comprised of several units that could be shipped and connected at a customer’s location, rather than the earlier massive units that had to be assembled on site. In 1953, IBM began shipping the first mass-produced computer, the IBM 650. IBM introduced the first solid-state (transistorized) computer in 1959, the IBM 7090. Then in 1964, IBM culminated over $1 billion in research when it brought out the System/360 series of computers. Unlike other mainframes, the System/360 computers were compatible with each other.
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By 1960, the computer was king. Companies hired armies of technicians and programmers to write its operating programs and software, fix it, and allocate the precious computer time. The capability of the machines was more than a mere mortal could fathom, but gathering raw data and “keying” it in so the computer could “crunch the numbers” was a complicated and time-consuming task.
Frustrations abounded, computer errors were called “glitches,” and the phrases “garbage in/garbage out,” “It’s a computer mistake,” and “Sorry, the computer’s down and we can’t do anything,” were introduced into the lexicon.
On college campuses in the 1960s, students carried bundles of computer cards to and from class, hoping that their share of the valuable computer time would not be bumped or allocated to someone else. The term, “Do not fold, spindle or mutilate,” was coined so people wouldn’t disable the process of feeding the punched computer cards into punch card readers, where the intricate patterns of holes were decoded.
The computer mystique was reinforced in people every time they heard of some new accomplishment. In 1961, a computer calculated the value of pi to 100,000 decimal places. A computer could play checkers, and in 1967 a chess playing computer program was made an honorary member of the United States Chess Federation. Banks began printing checks with magnetic ink so they could be processed by the computers.
3.4 New Technologies And Ideas
Until 1971, nobody even thought of a computer as anything but a big, fast, electronic brain that resided in a climate-controlled room and consumed data and electricity in massive quantities. In 1971, an Intel 4004 chip containing 4004 transistors was programmed to perform complex mathematical calculations; the hand-held calculator was born. Suddenly, scientists and engineers could carry
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the computational power of a computer with them to job sites, classrooms, and laboratories; but the hand-held calculator, like the ENIAC before it, was not yet a computer. The microprocessor was developed by Robert Noyce, the founder of Intel and one of the inventors of the integrated circuit, and brought with it a change in the way people worked.
Small, hand-held calculators had provided an idea, or at least a “what if,” to some people. Still, in the early 1970s, computers were used for number crunching and printing out long streams of green and white paper. IBM electric typewriters were the top of the line “word processors” and Xerox copiers churned out photocopies. Most people never imagined that a computer could process data in real time, be used to write letters, or fit on a desk.
In 1972, Intel brought out its 8008 chip, capable of processing 8-bits of data, enough to convey numbers and letters of the alphabet. In that same year, Xerox began working on a personal computer at their Palo Alto Research Center. For the next several years, a team of Xerox scientists worked on the “Alto,” a small computer that would have become the first PC if only the development team had been able to convince someone of its usefulness.
Likewise, in 1972 Digital Equipment Corporation (DEC), a minicomputer manufacturing company headed by Kenneth Olsen, had a group of product engineers developing the DEC Datacenter. This PC incorporated not only the computer hardware but the desk as well. The DEC Datacenter could have put tremendous computing capability in the home or at work, but management saw no value to the product and halted its development.
In the end, none of the giant companies whose names had been synonymous with computers would introduce the PC to the world. There seemed to be no future in an inexpensive product that would replace the million dollar “Big Iron” that they were selling as fast as they could make them.
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The people who eventually introduced the PC were rebels. Many had spent time in the bowels of the big companies and were frustrated by the lack of vision they encountered. They retreated into their own garages and attended meetings with other “computer nuts” who saw a much different future than the one laid out over the previous 30 years by the giants of the computer industry.
3.5 The Birth Of Personal Computer
In 1975, Rubik’s Cube was put on store shelves and proved to many that the human brain was incapable of complex problem solving. But a ray of hope also appeared; the first PC was introduced. Micro Instrumentation and Telemetry Systems, Inc. (MITS) sold a kit for the MITS Altair 8800 that enabled computer hobbyists to assemble their own computers. It had no monitor, no keyboard, no printer, and couldn’t store data, but the demand for it, like Rubik’s Cube, was overwhelming.
The Altair proved that a PC was both possible and popular, but only with those people who would spend hours in their basements with soldering irons and wire strippers. The Altair, which looked like a control panel for a sprinkler system, didn’t last, but it helped launch one of the largest companies in the computer world and gave a couple of young software programmers a start. In 1974, Bill Gates and Paul Allen wrote a version of BASIC for the Altair and started a company called Microsoft Corporation.
In 1976, another computer kit was sold to hobbyists – the Apple I. Stephen Wozniak sold his Volkswagen and Steve Jobs sold his programmable calculator to get enough money to start Apple. In 1977, they introduced the Apple II, a pre-assembled PC with a color monitor, sound, and graphics. It was popular, but everyone knew that a serious computer didn’t need any of this. The kits were just a hobby and the Apple II was seen as a toy. Even the Apple name wasn’t a serious, corporate sounding name like IBM, Digital Equipment Corporation, or Control Data.
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But 1977 also brought competition. The Zilog Z-80 microprocessor, which had been introduced in 1975, was used in the Tandy Radio Shack TRS-80, affectionately called the “Trash 80.” Apple, Commodore, and Tandy dominated the PC marketplace. The Apple II had 16K bytes of RAM and 16K bytes of ROM; Commodore Business Machines’ Personal Electronic Transactor (PET) included 4K RAM and 14K ROM; and the TRS-80 had 4K RAM and 4K ROM.
Also in 1977, the Central Program for Microprocessors (CP/M) operating system was developed by Digital Research and Gary Kildall. From its introduction until 1980, CP/M was used in most PCs, but even that did not guarantee that a program or document could be written on one machine and read on another because each manufacturer used different floppy disk drives.
Apple introduced the floppy disk drive in 1978, allowing Apple II users to store data on something other than the cumbersome and unreliable tape cassettes that had been used up to that point. But despite the popularity of the three PCs, non-computer people still saw little reason to buy an expensive calculator when there were other ways to do the same things. In 1979, that all changed.
When VisiCalc was introduced for the Apple II, non-computer people suddenly saw a reason to buy a computer. VisiCalc, a spreadsheet program created by Dan Bricklin and Bob Frankston, allowed people to change one number in a budget and watch the effect it had on the entire budget. It was something new and valuable that could only be done with a computer. For thousands of people, the toy, the computer few could find a use for, had been transformed into a device that could actually do something worthwhile.
Microprocessors and high-tech gadgets were gradually worming their way into people’s lives. In 1978, Sony introduced the Beta format video cassette recorder and a year later the VHS video recorder and the Sony Walkman. And to remind everyone of how
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far we had to go, Star Trek: The Motion Picture came to theaters in 1979.
The Sinclair ZX-80 PC, which hit the market in 1980, used the same Z-80 chip as Commodore’s PET and the Tandy TRS-80. The ZX-80 had 1K RAM and 4K ROM. Developed by British entrepreneur Clive Sinclair, the ZX-80 meant that people could enter the computer revolution for under $200. Its small size and price attracted people who had never thought about owning a PC.
The Commodore VIC-20, also introduced in 1980, had a color monitor and would eventually become the first PC to sell more than one million units. Even with all of the success the early PC manufacturers had in the late 1970s and early 1980s, the advances in microprocessor speeds, and the creation of software, the PC was still not seen as a serious business tool. Unknown to everyone in the computer industry; however, a huge oak tree was about to drop an acorn that would fall close to the tree and change everything.
Two events occurred in 1981 that would have a tremendous impact on the future of the PC. In 1980, IBM had started a secret project in Boca Raton, Florida called “Acorn.” Thirteen months later, in 1981, IBM introduced the IBM PC, a product that validated the PC as a legitimate business tool. For many people, even those who prided themselves on being able to operate the “Big Iron,” if IBM was making PCs then the small desk-top units were worthy of respect.
When the IBM PC hit the market, it was a complete system. Secretly, IBM had provided software developers with prototypes of their PC so they could develop an array of programs that would be available when the machine hit the streets. IBM also developed printers, monitors, and expansion cards for the PC and made it an open system so other manufacturers could develop peripherals for it. The IBM PC used an Intel 8088 microprocessor, had 16K of RAM, was expandable to 256K, came with one 5.25-inch disk drive and room for a second, and was available with a choice of operating
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systems; CP/M-86 or IBM PC-DOS, which had been developed by Microsoft.
The second major event of 1981 was the introduction of the first luggable computer, the Osborne 1. This self-contained, suitcase- sized PC, developed by Adam Osborne, was not only the first portable PC, but also the first to be sold with software. The Osborne I came with BASIC, CBASIC, WordStar for word processing, and the SuperCalc spreadsheet program. Over the next two years, the Osborne Computing Company would go from nothing to a company with $70 million in annual revenue and then into bankruptcy.
Prior to 1980, the most common method of storing data was to connect an audio tape recorder to the PC and dump data to standard tape cassettes. Large word processors and some PCs had 8-inch disk drives, but in 1980 Al Shugart introduced the Winchester hard-disk drive. The microprocessor, an amazing technology when it had 4000 transistors on a single chip, is now even more amazing when it has over 3 billion transistors on an even smaller chip. In 1982, when Time magazine made the computer its “Man of the Year,” the PC was still in its infancy. “Big Iron” still dominated the high-tech environment and having a personal computer was a luxury.
The creation and success of the PC would not have been possible without the elimination of the concept that a computer was a large, centralized, data processor and number cruncher. Today the PC is a communication channel more than it is a computational tool. Millions of people work in their “electronic cottages,” either operating their own business from home or telecommuting to work. It is strange that one of the first Intel 4004 microprocessors ever made continues to operate and lead the world to the outer edges of time and space. In 1972 one of the small chips was installed in the Pioneer spacecraft. Today it continues to operate over 5 billion miles from earth.
3.6 Industrial Contribution To Evolution Of Computer
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The early 1980s were a time of furious change in the computer industry. More than 100 companies were manufacturing PCs, each with its own unique features, each with its own software. When IBM entered the market in 1981, software companies knew that writing IBM compatible software would be profitable. Software for the Apple II had exploded to 16,000 titles and IBM would do the same. New software in the 1980s included WordStar, Lotus 1-2-3, Microsoft Word, and Word Perfect.
In 1981, Hayes Micromodem brought the MOdulator/DEModulator (MODEM) to the market for PCs. The modem had been invented at AT&T Bell Labs in 1960 to connect mainframes and minicomputers. Hayes’ modem allowed PCs to communicate with each other and access CompuServe and The Source, the online services that started up in 1979. CompuServe showed people what to do with their 300 baud modems by offering them an array of services and databases to connect with.
In 1982 Compaq introduced the first IBM compatible machine. Until Compaq, most manufacturers feared IBM and would not bring out a machine that was compatible with the PC. Later the compatibles would be termed “clones.”
Also in 1982, Tandy brought out the TRS-80 Model 16, which was based on the Motorola 68000 and Z-80 microprocessors. The Model 16 retailed for $5,000 and included 128K RAM, an 8-inch floppy disk drive, as well as the Xenix operating system, a derivative of UNIX.
In January, 1983 Time magazine anointed the PC as the “Man of the Year,” a designation by the editors that the computer had been the most influential newsmaker of 1982. The magazine estimated 80 million PCs would be in use by the end of the century. Industry leaders included Texas Instruments, Timex, Commodore, Atari, Apple, IBM, and Tandy, with Osborne leading the way in the portable market. The individuals pushing the PC into the future were John Opel at IBM, Adam Osborne of Osborne Computers, VisiCalc
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creator Dan Bricklin, Jack Tramiel of Commodore, and Clive Sinclair who founded Sinclair Research.
The leading products of 1982 and their sales figures included the Timex/Sinclair 1000 – 600,000; Commodore VIC-20 – over 600,000, Atari 400 and Atari 800 – 600,000; Texas Instruments 99/4A – 530,000; TRS-80 Model III – 300,000; Apple II Plus – 270,000; IBM
PC – 200,000; and Osborne 1 – 55,000. These computers ranged in price from the $99 Timex/Sinclair to the Osborne 1 at $1,795 with bundled software. In the opinion of Time, computers priced over
$2,000 would appeal to a market of “…growing small businesses and big corporate clients…” Manufacturers of these higher end PCs included Altos, Corvus, Cromemco, Control Data, Digital Equipment, Hewlett-Packard, North Star, Olivetti, Tele Video, Toshiba, Xerox, and Zenith.
In 1983, there was once again a wind of change blowing across the PC landscape. Apple brought out a machine that failed to sell but nonetheless showed consumers and manufacturers a new direction for the PC. The Lisa, an expensive PC with a graphical user interface (GUI), hit the market with a thud. At $10,000, it had few friends and even fewer buyers. Also in 1983, IBM introduced IBM XT with a 10MB hard drive, three additional expansion slots, 128K RAM, and a 360K floppy drives. To many buyers, the 10MB storage capacity seemed large enough to last a lifetime.
Immediately after the failure of Lisa, Steven Jobs rethought the machine and in 1984, out came the Macintosh. The Macintosh was powered by Motorola’s 68000 processor and came with 128K of RAM. It was so radically different from any other PC that it split the PC world into two halves that would not be rejoined for another decade. In addition to the GUI that made the computer an “intuitive” extension of the user, the “Mac” had its own operating system that was incompatible with IBM’s MS-DOS system. Suddenly PC meant DOS-based and IBM compatible and Mac meant GUI and mouse.
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The Mac was introduced to the world in an extravagant television commercial that was shown only once during half-time of the NFL Super Bowl. The commercial changed the advertising industry almost as much as the Mac changed computing. Suffering from the failure of the Apple III and Lisa, Apple was literally saved by the Mac. People who hated computers loved the simplicity of Mac. The GUI allowed the user to click a mouse button on an icon to launch a program, print a document, or copy a file. No longer did users have to know combinations of keys or special codes to get the computer to do what they wanted it to do. The Mac was “user friendly.”
When Apple came out with the Apple LaserWriter in 1985 it was with Adobe Systems Inc.’s PostScript page description language. By 1986, with its what-you-see-is-what-you-get (WYSIWYG) display and printing, desk-top publishing was born. WYSIWYG meant that a person could format a document with special fonts and spacing and be assured that what came out of the printer would look like what they had created on the screen.
Adobe, founded in 1982 by John Warnock and Charles Geschke, turned the printed page into a graphic image. The bit map made each pixel on the screen a definable image that could be moved and changed without the limitations of a standard text format. PostScript changed the way people thought about fonts, page layout, and the visual impact of the documents they produced with their PC. Printers like the Apple LaserWriter and the Hewlett-Packard HP LaserJet made every document look like it had been professionally typeset and printed.
In 1985, the Commodore Amiga 1000, which featured multitasking, graphics, sound, and video in a windowing operating system, exposed people to multimedia. At the same time Toshiba came out with the T1100 laptop, Tandy introduced the Tandy 200 laptop, and AT&T introduced the UNIX PC. Intel took the microprocessor to a new level when it brought out the 386 microprocessor in 1985,
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proving that PCs were not only getting better, but they were also getting faster.
The 1980s were very active times for hardware manufacturers and software producers. Small software companies locked in with either IBM or Macintosh, but large companies like Microsoft were able to create new applications for both operating systems. While Aldus brought out PageMaker, and Lotus introduced Jazz, Microsoft announced Excel for the Mac, C 3.0, and finally shipped a long-awaited program called Windows.
Bill Gates, a founder of Microsoft, tried three times to interest IBM in Windows but was turned down each time. Although the Mac operating system had changed the interface between users and their PCs, many DOS users continued to hang on to their command line- driven MS-DOS operating system, and it would be several more years until the Windows concept caught on.
With the availability of hundreds of software programs, hard disk space became valuable real estate. The 10MB hard disk on the IBM XT began to fill up so hard drive manufacturers started the process of doubling their capacity.
As modems proliferated and the Hayes Smart modem was accepted as the standard for modems, just about everyone either knew someone they could get online with, subscribed to an online service such as CompuServe, or wanted to access the 1000 host sites on the Internet. But PCs that were connected to the outside world were also vulnerable to a new phenomenon called viruses. Once downloaded, these programs could attach themselves without warning to a PC’s hard drive and gradually or in the blink of an eye destroy or overwrite files. Virus checkers then became the rage for anyone who received data over telephone lines.
By 1987 enough people were writing their own software and sharing it that the Association of Shareware Professionals was formed to market and protect the inexpensive software. In 1987 a new
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computer language, C++, stimulated the growth of object-oriented programming (OOP).
In 1990, Intel’s 386 and Motorola’s 68030 microprocessors were at the top, then in 1991 Intel brought out the i486SX 20 MHz chip and Motorola introduced the 68040. Less than a year later Intel introduced the 50MHz 486 chip and Tandy brought out its $400 CD- ROM drive for PCs. Then, just to make everyone wonder what was going on, in 1991 Apple and IBM agreed to share technology by integrating the Mac into IBM’s systems and using the IBM Power PC chip.
In 1992, Apple brought out the Apple PowerBook, a laptop that made everyone wonder just how small a full-function computer could get. A year later everyone knew the answer when Apple introduced the Newton Personal Digital Assistant (PDA). The Newton was supposed to be able to recognize hand-written notes and Apple sold 50,000 of them in 10 weeks.
In 1993, Intel introduced the 60MHz Pentium chip, the next generation of chips. The Pentium; however, had a nasty mathematical bug and its acceptance was slowed. Apple discontinued the workhorse of its fleet, the Apple II, which, despite the mind boggling changes in the industry, had lasted 17 years. From its inception in 1975, the PC has become a focal point of business, education, and
omputer is a device that is capable of automatically accepting (i.e. input), storing and processing data into useful information (i.e. output), at a very high speed, under the control of stored instructions (i.e. program). A computer could also be defined as a machine for manipulating data according to a list of instructions (programs). The computer is the backbone of ICT.
2.2 Parts of a Computer
If you use a desktop computer, you might already know that there isn’t any single part called the “computer.” A computer is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware. (Software, on the other hand, refers to the instructions, or programs, that tell the hardware what to do.)
The illustration below shows the most common hardware in a desktop computer system. Your system may look a little different, but it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.
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2.2.1 System Unit
The system unit is the core of a computer system. Usually it’s a rectangular box placed on or underneath your desk. Inside this box are many electronic components that process information. The most important of these components is the central processing unit (CPU), or microprocessor, which acts as the “brain” of your computer. Another component is random access memory (RAM), which temporarily stores information that the CPU uses while the computer is on.
The information stored in RAM is erased when the computer is turned off. Almost every other part of your computer connects to the system unit using cables. The cables plug into specific ports (openings), typically on the back of the system unit. Hardware that is not part of the system unit is sometimes called a peripheral device or device.
2.2.2 Storage
The computer has one or more disk drives—devices that store information on a metal or plastic disk. The disk preserves the information even when your computer is turned off.
2.2.3 Hard disk drive
Computer’s hard disk drive stores information on a hard disk, a rigid platter or stack of platters with a magnetic surface. Because hard disks can hold massive amounts of information, they usually serve as your computer’s primary means of storage, holding almost all of your programs and files. The hard disk drive is normally located inside the system unit.
Figure 2b. Hard disk drive
2.2.4 CD and DVD Drives
Computers today come equipped with a CD or DVD drive, usually located on the front of the system unit. CD drives use lasers to read (retrieve) data from a CD, and many CD drives can also write Page 19 of 288 Information Communication Technology (ICT)
(record) data onto CDs. If you have a recordable disk drive, you can store copies of your files on blank CDs. You can also use a CD drive to play music CDs on your computer.
Figure 2c. CD
DVD drives can do everything that CD drives can, plus read DVDs. If you have a DVD drive, you can watch movies on your computer. Many DVD drives can record data onto blank DVDs.
2.2.5 Floppy disk drive
Floppy disk drives store information on floppy disks, also called floppies or diskettes. Compared to CDs and DVDs, floppy disks can store only a small amount of data. They also retrieve information more slowly and are more prone to damage. For these reasons, floppy disk drives are less popular than they used to be, although some computers still include them. Why are floppy disks “floppy”? Even though the outside is made of hard plastic, that’s just the sleeve. The disk inside is made of a thin, flexible vinyl material
Figure 2d. Floppy disk
.
2.2.6 Mouse
A mouse is a small device used to point to and select items on your computer screen. Although mice come in many shapes, the typical mouse does look a bit like an actual mouse. It’s small, oblong, and connected to the system unit by a long wire that resembles a tail. Some newer mice are wireless. A mouse usually has two buttons: a primary button (usually the left button) and a secondary button. Many mice also have a wheel between the two buttons, which allows you to scroll smoothly through screens of information.
Figure 2e. Mouse
When you move the mouse with your hand, a pointer on your screen moves in the same direction. (The pointer’s appearance might change depending on where it’s positioned on your screen.) Page 21 of 288 Information Communication Technology (ICT)
When you want to select an item, you point to the item and then click (press and release) the primary button. Pointing and clicking with your mouse is the main way to interact with your computer.
2.2.7 Keyboard
A keyboard is used mainly for typing text into your computer. Like the keyboard on a typewriter, it has keys for letters and numbers, but it also has special keys:
The function keys, found on the top row, perform different functions depending on where they are used.
The numeric keypad, located on the right side of most keyboards, allows you to enter numbers quickly.
The navigation keys, such as the arrow keys, allow you to move your position within a document or webpage.
Figure 2f. Keyboard
Note: We can also use your keyboard to perform many of the same tasks you can perform with a mouse.
2.2.8 Monitor
A monitor displays information in visual form, using text and graphics. The portion of the monitor that displays the information is called the screen. Like a television screen, a computer screen can show still or moving pictures.
There are two basic types of monitors: CRT (cathode ray tube) monitors and LCD (liquid crystal display) monitors. Both types produce sharp images, but LCD monitors have the advantage of being much thinner and lighter. CRT monitors, however, are generally more affordable.
A printer transfers data from a computer onto paper. You don’t need a printer to use your computer, but having one allows you to print e-mail, cards, invitations, announcements, and other materials. Many people also like being able to print their own photos at home. The two main types of printers are inkjet printers and laser printers. Inkjet printers are the most popular printers for the home. They can print in black and white or in full color and can produce high-quality photographs when used with special paper. Laser printers are faster and generally better able to handle heavy use.
Speakers are used to play sound. They may be built into the system unit or connected with cables. Speakers allow you to listen to music and hear sound effects from your computer.
Figure 2i. Computer Speakers
2.2.9. Modem
To connect our computer to the Internet, we need a modem. A modem is a device that sends and receives computer information over a telephone line or high-speed cable. Modems are sometimes
built into the system unit, but higher-speed modems are usually separate components.
Figure 2j. Cable Modem
2.3 Advantages of Computer System
Below are some advantages of computer systems
i. Accuracy and Reliability: The results produced by a computer are extremely correct and reliable. What is often called ‗computer errors‘ are actually human mistakes; invalid data and errors are corrected easily.
ii. Speed: The speed of computer makes it the machine ideal for processing large amounts of data; e.g. accounting, banking operations etc.
iii. Storage/Memory Capability: Computer systems can store tremendous amounts of data, which can then be retrieved fast
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and efficiently. The volume of information we deal with today is far beyond what we can handle manually.
iv. Productivity: Computers are able to perform dangerous, boring, routine jobs, such as adding long list of numbers, punching holes in metal or monitoring water levels. Most workers (e.g. in banks) will appreciate increased productivity when computers are used to do their jobs.
v. Flexibility: Computer could be used for various purposes
e.g. multiprogramming, batch processing, real-time processing, data collection, bank transaction processing etc.
vi. Automatic operation: Computer performs data processing automatically under the control of internally stored programs.
vii. Configuration and adaptability: Different or suitable peripherals may be used by business organizations to suit their business processing requirements.
2.4 Disadvantages of Computer System
Some of the dis-advantages of computers are discussed below
i. Cost of initial setup may be high.
ii. Cost of maintenance may be high.
iii. Inefficient feasibility study before implementation may hamper business operations.
iv. Lack of skilled personnel may hamper computer operations and results obtained.
v. Requires regular electrical power supply.
vi. Excessive exposure to computer may result in some health problem such as poor eye sight, wrist pain, back ache, neck pain etc.
vii. Computer virus attack may infect and destroy Data/information, which will automatically affect business operations.
viii. It may lead to unemployment, because one computer can do the job of about 10 persons.
2.5 Application of Computer in Society
Computers have moved into many facets of our lives. There is virtually no area of human endeavor that computer usage has not penetrated. Though we cannot exhaust listing all the areas of application of computers, the following are some key areas of computer application:
Science: One of the most important advantages of computers is in the field of science for research and development. The computers have played a major role in most of what we know about ourselves and the universe. The satellites, the telescopes and almost all the research tools make use of computers in some or the other way. The huge calculations required for space science, safe communication between scientists, storage of all the gathered information are some of the computer uses in science and technology.
Medical: The important use of computers in the medical field is for research and development. The high end machines used for diagnosis and cure of many diseases are nothing but computers. For example, the Magnetic Resonance Imaging (MRI), CT scan, ultrasound devices, etc are amongst the uses of computers in hospitals. Even many surgical procedures, known as laparoscopic surgeries, need the help of computers. Web conferencing helps doctors treat people remotely.
Education: Computer uses in the field of education are infinite. The Internet is a huge source of information. There are online universities that deliver online degrees and distance learning is spreading far and wide. Many schools and colleges have started making use of audio-visual ways of
imparting knowledge. A horde of tools that need a computer, help students in many ways.
Banking: The banking sector has improved on fronts such as security, ease of use, etc. with the help of computers. Most of the banking operations can be done online, known as Internet banking, and you don’t have to walk up to the bank for virtually anything. You can withdraw money from ATMs and deposit money in any branch, thanks to the networking affected by the use of computers. The complete banking experience has also become safer.
Crime Investigation: High end computer devices have ensured that justice is more effective. CCTV cameras and other computer operated security systems have reduced the amount of crime. And if it still happens there are many ways to track down the criminal in no time. Forensic science employs computers for many of its operations related to investigations.
Entertainment: The field of entertainment has been revolutionized by computers. Animation, graphic image manipulation etc has made the entertainment experience hundred times better. Computer gaming is achieving new landmarks in terms of technology. Movie making, editing, music composition etc everything needs computers. This is only the tip of the iceberg and the uses of computers in society are many more. But then the development of computer technology has also given rise to many vices like identity theft.
Government: The Government can use computers for the processing of immigration, tax collection/administration, keeping tracks of criminals, computing budgets and statutory allocations, Civil Service Records, computing wages, salaries, gratuities and pensions etc.
Communication: Any computer has any potential to link up with other computers through communication systems such as telephone lines or satellite. This link-up facilitates exchange of memos, reports, letters, data/information, and even having meetings among people in geographically dispersed locations.
Robotics: Robots are information machines with the manual dexterity to perform tasks too unpleasant, too dangerous, or too critical to assign to human beings. For example, robots are used in defense to perform underwater military missions; robots could be used for welding or paint-spraying in factories, and in car assembling.
Business/Commerce: Products are packaged with zebra- striped symbols (Universal Product Code {UPC}) that can be read by scanners at supermarket checkout stands to determine prices of commodities. It has become a commonplace for companies and consumers to transact business among themselves with the help of computers. It could be in form of Business-to-Business {B2B} or Business-to-Consumer {B2C}. Computers have been found useful in payroll preparation, inventory control, auditing operations, personnel records keeping, preparation of consumer utility bills, financial market transactions etc.
Energy: Energy companies use computers and geological data to locate oil, coal, natural gas and other mineral resources. Meter-readers use hand-held computers to record how much energy is used in a month in homes and businesses. Computers can analyze the fuel consumption in our cars.
2.6 Types of Computer System
Classifications of computer vary and also depend on some criterion as discussed below:
Criterion 1: Types by Data Processed
There are three (3) types of computers according to this classification criterion:
Analog Computers: An analog computer measures and operates on data that are represented in the form of continuous variables e.g. voltage, pressure, temperature, distance, speed etc. Examples of analog computers include car speedometer, multimeter, fuel pump at filling stations etc.
Digital Computers: A digital computer represents and processes data in discrete/numerical form, using binary system. It produces discrete output. Most computer systems we see around us today are digital computers; they are found in our homes and business environments. Some wrist watches today have digital computers embedded in them. Examples include desk calculators, adding machines, personal computers etc.
Hybrid Computers: A hybrid computer combines the features of both analog and digital computers. It can accept continuous, discrete or both type of input. Its output could be in the form of discrete or continuous values or the combination of both. This type of computer is commonly found in highly scientific environments. Example is the electronic calculating scale used in food stores.
Criterion 2: Computer Types by physical size
In classifying computer according to physical size, there are four (4) types, namely and computers in this category are digital in nature:
Microcomputers: Microcomputers are the smallest in size; they are the cheapest; and they have the least operational speed and memory capacity. They are made for single user and single-tasking. They are portable (i.e. they can be moved about easily), easy and simple to learn and use. The microprocessor of a microcomputer is made of integrated circuits, called chip, mounted a single circuit board. It has interfaces for input, output and storage devices. Examples include IBM Personal Computers and compatible systems, Compaq, Dell etc. Microcomputers come in different shapes and sizes: Personal Computer (PC) System: is a microcomputer designed for independent use by an individual at work or in the home mainly for business purposes. Some PCs are called Home Computers because they have limited capability designed for domestic use with programs that are typically used for computer games and controlling family finances.
Minicomputers: Minicomputers are medium-sized, general- purpose digital computers; a bit larger than microcomputers but smaller than mainframe computers. They are multi-user (i.e. supports many users at a time) and multi-tasking (i.e. ability to perform many tasks simultaneously). Compared with microcomputers, they have larger memory size, higher processing speed, more numerous and faster input/output devices; and they are costlier. They are used in small-scale industries. Examples of mini-computer include: PDP-8, PDP-11, Honeywell-DPS6, DEC‘s VAX series, Texas instrument DS990, IBM 8100 etc.
Mainframe computers: Mainframe computers are generally more powerful in terms of processing speed than minicomputers. They have larger memory storage memory/capacity and cost more than minicomputers. They are multi-user and multi-tasking oriented, supporting full range of programming languages, used for commercial and scientific research purposes, with sophisticated devices attached. They can access numerous terminals/workstations on a network. They use different types of peripheral devices such as tapes and disks. They are operated by well-trained
experts. Examples of mainframe computers include: NCR 8000, IBM 370,
Super computers: Supercomputers are the largest, fastest and most expensive computers. They are often referred to as Maxi-computers. They can be seen as technological improvement on mainframe computers. They are often used in scientific environments such as in space studies and weather forecast. Examples include: CRAY-1, CRAY-2
Criterion 3: Computer Types by Purpose
There are two types of computers according to classification by purpose:
General purpose computers: General purpose computers are designed to solve wide range of problems such as science, technology, education, business etc. Complex calculations are performed within fractions of a second and results obtained fast. Most Personal Computers (PCs) are general purpose computers.
Special purpose computers: Special purpose computers are designed for a particular job/purpose only; to solve problems of a restricted nature. They are also called dedicated computers. Most special purpose computers are put within some other devices or systems, such that the computers are not accessed directly. These types of computers are called Embedded Computers. Examples include computers designed for use in digital watches, micro-wave oven, in petrol pumps or in weapons guidance systems.
Criterion 4: Computer Types by generations/Technology Age There are five (5) generations of computers as at date based on this criterion.
First Generation Computers: These are computer systems manufactured during the 1940s. Their features include
The CPU was made of vacuum tubes or thermionic valves.
Primary memory made of magnetic drum.
The Visual Display Unit (VDU) or monitor used cathode ray tube.
Very bulky in size, occupied space, and very costly.
Used machine language programming.
Complex and cumbersome to operate.
Generated a lot of heat.
Examples are: EDSAC, EDVAC, LEO, UNIVAC I and UNIVAC II.
Second Generation Computers: These are computer systems manufactured during the 1950s. Their features include:
The CPU was made of electronic transistors.
Primary memory made of magnetic core.
Cost less, faster, smaller and more reliable than first generation systems.
Less complex and easier to operate compared with first generation.
Generated less heat than first generation.
Examples: LEO Mark III, ATLAS, Honeywell 800, UNIVAC III, IBM 7000 series, etc.
Third Generation Computers: These are computer systems manufactured around the 1960s and early 1970s.
Features:
The CPU was made of Small Scale Integrated (SSI) Circuits, built on one Silicon Chip.
The SSI circuits evolved to Medium Scale Integrated (MSI) circuits.
The MSI eventually evolved into Large Scale Integrated (LSI) circuits, leading to greater degrees of integration of electrical components.
The various evolutions of IC technologies gave rise to computer systems which were smaller in size, cheaper, faster, more reliable and durable than first and second generation systems.
It was the era of minicomputers and microcomputers, resulting in higher awareness of computer technology.
The VDU were in colours.
Primary memory made of magnetic core and solid state semi-conductors.
Less complex and easier to operate compared with first and second generations.
Used high level language e.g. COBOL for operation. Examples: ICL 1900 series, IBM 360 series etc.
Fourth Generation Computers: These are computer systems manufactured around the late 1970s to 1985. Features include the following:
The CPU was made of Very Large Scale Integrated Circuits (VLSIC), called microchips; i.e. thousands of components in a very small space.
There was a thin line demarcation between third and fourth generations.
The VLSI circuits gave rise to computer systems which were more compact, cheaper, faster, more reliable and durable than first, second and third generation systems.
It was the era of microcomputers, resulting in higher awareness of computer technology.
Invention of microprocessors, which gave birth to pocket calculators, digital watches and the inclusion of micro hips in other devices.
Use of fourth generation query language (4GLs).
The VDU were in various designs – RGB, EGA, CGA, VGA colour monitors.
Primary memory made of solid state semi-conductors.
Less complex and easier to operate compared with first and second generations.
Evolution of more application areas of computers.
v. Fifth Generation Computers
The research into the fifth generation computers started about 1985 and continued into 1990. The features are as follows:
This generation is characterized by the advent of Artificial intelligence, i.e. the ability of computer system to exhibit behaviors like an intelligent person.
Speech recognition/processing
Parallel architecture/processing – where a computer system have hundreds of processors that could all be working on different parts of a single complex problem simultaneously.
Pattern recognition –
Expert system – an application program that has the capability of making judgments and decisions like a human expert in a particular field of profession. It is an interactive system that puts users through question-and-answer session to clarify issues and make recommendations, e.g. in medicine.
Multimedia system – PC + Sound Card + Speakers + CD Drive
Semi-conductor memory.
2.7 Social Implication Of Computer System
The society in which we live has been so profoundly affected by computers that historians refer to the present time as the information age. This is due to the ability to store and manipulate large amounts of information (data) using computers. As an information society, we must consider both the social and ethical implications of our use of computers. By ethical questions we mean asking what are the
morally right and wrong ways to use computers and this could be explain as follows:
Ergonomics: this is the science that studies safe work environments. Many health-related issues, such as carpal tunnel syndrome and computer vision syndrome (CVS), are related to prolonged computer use.
Environmental concern: Power and paper wastes are environmental concerns associated with computer use. Suggestions for eliminating these concerns include recycling paper and printer toner cartridges and turning off monitors and printers when not in use.
Employee monitoring: Employee monitoring is an issue associated with computers in the workplace. It is legal for employers to install software programs that monitor employee computer use. As well, e- mail messages can be read without employee notification. The invasion of privacy is a serious problem associated with computers. Information: Because computers can store vast amounts of data we must decide what information is proper to store, what is improper, and who should have access to the information. Every time you use a credit card, make a phone call, withdraw money, reserve a flight, or register at school, a computer records the transaction. These records can be used to learn a great deal about you—where you have been, when you were there, and how much money was spent. Should this information be available to everyone?
Computers are also used to store information about your credit rating, which determines your ability to borrow money. If you want to buy a car and finance it at a bank, the bank first checks your credit records on a computer to determine if you have a good credit rating. If you purchase the car and then apply for automobile insurance, another computer will check to determine if you have traffic violations.
The Ethical Responsibilities of an IT Professional
IT (information technology) professional has responsibilities that relate to system reliability. System reliability involves installing and updating appropriate software, keeping hardware working and up- to-date and maintaining databases and other forms of data. Professional ethics helps a professional choose what to do when faced with a problem at work that raises a moral issue. One can certainly study what professionals do when faced with such problems, and confine the enquiry to the description. Our concern here, however, is to assist with making choices – an approach called prescriptive professional ethics.
Governments, schools, and employers rely on IT professionals to maintain their computer systems. In addition to ensuring system reliability, an IT professional must take responsibility for the ethical aspects of the career choice. The lists below are the most commonly reported behaviors IT professional which is unethical;
Plagiarism
Failure to protect confidential data
Failure to share credit on a report
Fabrication of data
Criticize the ability/integrity of colleague for own gain
Holding back or disguising data
Design of sampling strategy to favor a specific outcome
Destruction of data that contradicts desired outcome
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