December 15, 2022

Introduction In this chapter, we undertake a case study entitled Bukuma information system. The objective of this case study is to help the student apply the system development techniques learnt in Form 3. We shall address each step that is required in developing a working information system. 5.2 . Preamble Due to your expertise and experience in system development, you have been hired to be the head of Information Technology (IT) at Bukuma Limited, a company that runs a supermarket. Your first task is to develop a computer based information system that would ensure that: Stock control and monitoring is efficient and effective. Customers’ orders are processed accurately within the shortest time possible and invoices sent in time. Purchase orders are processed accurately in time t~ avoid delays in items delivery. Data entry screens or forms are easy to use hence eliminating data entry errors. On-demand reports by the management are generated within the shortest time possible. Communication between the branches is efficient. Company data and information is secure from unauthorised users and only certain company employees can access certain reports. The overall operating cost is reduced by at least 40%. By the end of this case study, we shall have demonstrated how to: Carry out the initial study. Carry out fact finding. Define system hardware and software requirements. Design a system using system and program flowcharts. Construct a system that would allow: Inputting of data through forms. Updating, modification, deletion of existing data. Carrying out of input validation and integrity checks. Search or filter specific records, query and retrieve specific records. Generate various transaction reports. Set up database security, menus and other startup options. A sample user manual has been provided to help the student identify some components of a good user manual. Identification and definition of the problem The problem at hand is to develop a computer based transaction processing system (TPS) that would capture and process data about business transactions. The system should also do data maintenance i.e. provide for ability to update stored data. Some features of this system include: Input data collected from transactions products, orders etc. Output in the form of invoices, pay vouchers etc. The system is also supposed to produce a variety of reports that are to be used for managerial purposes. Such reports include inventory levels, sales reports, payroll, expenses etc. Reports produced by the system can be classified according to purpose. These are: Summary reports – Shows totals and trends such as total sales by category. Track stock levels and automatically alert the purchases department when restocking is necessary. Produce monthly product sales and purchases reports. In a nutshell, the following project charter outlines the objectives, preliminary investigation report and other pertinent issues that will be considered before embarking on system development: Project charter for Bukuma information system BUKUMA DISTRIBUTORS LTD.              lndustrial area, Funzi Road Box 30307, NairobiKenya Phone: 257- 020655147 Fax: 02065551418 Computerised transaction Processing and stock control system Project name: Bukuma computerised information system Team leader: Jane Okindia, System analyst Project objectives The project development team will develop new computerised information system tl1at will support the operations of the company in order to realise the strategic vision for Bukuma products sales and delivery of customer services. It’s anticipated that the new system will provide highly integrated processes and. services that will not only reach out directly to customers and suppliers but also increase internal operational efficiency. Therefore, improvement to the current system can result in a number of benefits. These include: Improving corporate profits by 10% through reduction of bouncing orders. Ensuring improved customer services by efficiently managing stock levels. Improved employee’s morale due to better processing and operations management. 4. Improved internal decision support so that decisions are more reliable and made on time. Support the competitive strategy of the business. Preliminary investigation preliminary investigation and feasibility study of the current manual system and the proposed was done through: Studying the organisational chart. Quantifying work output against performance criteria. Observing the behaviour of the employees. Listening to external feedback from vendors, customers and suppliers. By going through the investigative process, the team discovered the following problems with the current manual system. The constantly changing products presented to the market have created numerous internal inefficiencies and customer service problems. Increased customer base and sales through aggressive advertising may overload the current system’s ability to process transactions. Unpaid orders have increased from 4%, only two years ago, to 12%. The current credit management system has to be improved. Suppliers who have failed to deliver as per contracts have increased by 17% due to poor procurement procedures. Competition from other companies threatens the survival of the company unless there is a change in management strategies. Many orders are bouncing due to poor stock control. The orders that bounce are not given priority when new stock arrives. The management is not exploiting the Internet as a marketing and service delivery channel. Scope of the system The proposed computerised system will support the following internal business functions: Sales and customer order transaction processing. Inventory control and procurement processing. Team vision The strategic information management team has come up with the following recommendations for the new system. Adoption of automated data capture technology and methods e.g. using bar-coding as a means of capturing product stock records and sales, which is an automatic identification system currently being implemented in many modem business organisations. Triple the order processing capacity of the unit by the end of fiscal year. Reduce order response time by 50% by the end of fiscal year. Rethink any underlying business processes, procedures and policies that have any visible impact on member satisfaction and complaints. Provide improved marketing and promotion programs. Provide improved follow-up mechanisms for orders and backorders. Feasibility of the proposed system The feasibility analysis of the proposed system centered on the following: Feasibility report Schedule: The system would take 9 months to develop. The technology required to develop the new system is readily available in the market. 

Introduction The era of computers and automated information and communication technology has brought both blessings and disappointments in the workplace. Some people have acquired very well paying jobs while others have lost theirs. For example an ordinary typist has been replaced by one who can create documents using a computer. Many new jobs have been created in areas like banking, manufacturing, educational institutions, communication and other service industries. Description of career opportunities in the field of ICT Information and communication technology (ICT) has created new job titles such as computer operators, computer technicians, system analysts, computer programmers, software engineers, computer engineers, information systems manager, data base administrator, computer trainer, website administrators, computer graphics designers and network administrators. This section explains some responsibilities of these professionals who are generally called information technology workers. Computer operator Some of the responsibilities of a computer operator include: Entering data into the computer for processing. Keeping up-to-date records (log files) of all information processing activities. Computer technician Given that computers require regular maintenance, upgrading as well as emergency repairs, demand for computer technicians continues to grow as more and more people computerise their workplaces and homes. Some of the responsibilities of a computer technician are: Troubleshooting computer hardware and software related problems. Assembling and upgrading computers and their components. Ensuring that all computer related accessories such as printers, modems, storage media and devices are in good working condition. In developed countries, technicians help hardware engineers in designing and creating some computer components such as storage devices, motherboards etc. System analyst This is a person who is responsible for analysing a company’s needs or problems then designs and develops a computer based information system. A good system analyst is one who has at least the following attributes: Good problem solving skills and creativity i.e. must have wide experience in solving problems. Good communication skills: The analyst must be able to communicate clearly and precisely both in writing and in speech. He/she must be able to talk to different groups of people e.g. managers, operators, attendant and general public. Must have business knowledge: The analyst must clearly understand the environment for which the system is being developed. Technical knowledge: A system analyst must be well trained in relevant areas of computer science such as hardware, software and programming knowledge. Some of the responsibilities of a system analyst include: Reviewing the current manual or redundant information system and making recommendations on how to replace it with a more efficient one. Working with programmers to construct and test the system. Coordinating training for users of the new system. Computer programmer Large organisations such as insurance companies, banks, manufacturing firms and government agencies hire programmers to work together with system analysts in order to: Write in-house application programs or system programs. Customise commercial application packages to suite the organisations needs. 3. Test, debug, install and maintain programs developed or customised for the organization. Software engineer A software engineer is one who is skilled in software development and technical operation of computer hardware. Some of the responsibilities of the software engineers are: Developing system and application software. Developing user and technical documentations for the new software. Maintaining and updating the software to meet day-to-day requirements while overcoming challenges. Computer engineer Computer and electronic engineers are coming up with new and more efficient technologies in information and communication technology almost daily. Since computers are electronic devices, hardware designers must be good in electronic engineering in order to be able to: Design and develop computer components such as storage devices, motherboards and other electronic components. Determine the electrical power requirement of each computer component: Re-engineer computer components to enhance its functionality and efficiency. Design and develop engineering and manufacturing computer controlled devices such as robots. Information system manager The information system manager controls, plans, staffs, schedules and monitors all the activities of the ICT department in the organization. Using computerised management information system (MIS), the manager can test the impact that an alternative course of action might have on the business. Other responsibilities of an information system manager include: making sure that all tasks in the IT department are done correctly and on time in order to support business planning, control and decision making processes. Preparing budgets for the department. Keeping the department inventory records up-to-date. Managing the human resource within the department. Database administrator (DBA) The major purpose of computerising organisations or institutions is to store data in an organised way for easy access, retrieval and update. The organization requires a person who should be responsible for updating records in an information system database. For this reason, a database administrator is responsible for: Designing and developing database applications for the organization. Setting up security measures needed to control access to data and information. Keeping the database up-to-date by adding new records, modifying or deleting unnecessary records. Computer trainer Due to the dynamic nature of computers and information technology, there is a high demand for qualified ICT trainers. Some of the responsibilities of an ICT trainer are: Training people on how to use a computer and various application programs. Developing training reference materials. Guide learners on how to acquire knowledge through carrying out research. Advising the learners on the best career opportunities in the broad field of ICT. Preparing learners for ICT examinations. Web administrator/webmaster Internet is one of the areas of information and communication technology that has drawn the interest of most people. Thus people are able to exchange messages, search for information and do business through the Internet. Business organisations, educational institutions and individuals put information on the Internet by developing websites. Most organisations hire the services of a web developer who is given the role of the company’s web administrator also referred to as a webmaster. A web administrator is responsible for: Developing and testing websites. Maintaining, updating and modifying information on the web site to meet new demands by the users. Monitoring the access and use of internet connection by enforcing security measures. 4. Downloading information needed by

Introduction This era of information and communication technology (ICT) continues to influence our lifestyle both positively and negatively. This chapter seeks to explain some of the issues that result from the use of ICT in the society. Issues resulting from the use of ICT The use of ICT offers a different set of opportunities and challenges in our society. Some of the effects of ICT in our society are: Effects on employment. Effects on automated production. Issues of workers’ health. Cultural effects. Breakthroughs in ICT. Effects on employment The introductions of computers in the workplace have resulted in creation of new jobs, replacement of computer illiterate workers and displacement of jobs that were formerly manual. Job creation ICT has introduced new employment opportunities that never existed before. The use of computers in financial institutions, reservation systems, educational institutions, communications etc. has created new job titles such as computer operators, programmers, network administrators, information technology or infof?1ation science managers, database administrators, software developers, system analysts etc. Job replacement Since the introduction of ICT in workplaces, some clerical and repetitive tasks that required a large number of employees have been made redundant. Computer illiterate people have been replaced with those who have the desired computer skills. The question in the mind of workers and managers is whether computers will in future take over all the work currently being done manually by human workers. Displacement Unlike in replacement where an employee may lose the job, in displacement an employee is moved to another place or department where computer skills are not required. For example, a clerk may end up being an office messenger if computers are introduced at the workplace and such a person is not willing to acquire new skills of using the computerised system. However, to avoid losing competent employees, most employers organise in-service training for their employees on regular basis in order to help them keep up with the rapid changes in ICT. Automated production A number of manufacturing industries such as vehicle assembly plants, oil refineries and food processing companies are using computers to automate their processes with an aim of increasing production. Computer controlled robots and assembly lines are a common feature in manufacturing industries. The advantages of using automated production are: Increased efficiency due to the balancing of workload and production capacity. Improved customer service. Adequate and high quality goods are produced in time. Efficient utilisation of resources such as raw materials, personnel and equipment hence less operating expenses are incurred. However, automated production has its disadvantages too. These are: High initial cost of setting up 1an automated system. For example, the cost of buying one industrial robot is high compared to employing human resource. Automated production may lead to unemployment in some areas that are labour intensive. For example, what would have been done by thirty people may be done by one person using a machine.  Issues of workers’ health The use of information and communication technology (ICT) and computers has some effect on our health. Some of the negative effects of ICT on our health include repetitive strain injuries, eye strain and headaches, electromagnetic emissions and environmental issues.   Repetitive strain injuries (RSI) These are injuries resulting from wrist, hand, arm and muscle strain, tendonitis and neck strains due to forced repetitive movement e.g. when entering data using the keyboard. The cure for repetitive strain injuries is resting, sitting in a relaxed position and changing typing techniques. Eye strain and headaches Since computer users have their eyes at cross range with the monitor, there is danger of developing what is called computer vision syndrome (CYS). The syndrome is characterised by eye strain, headaches, double vision and other problems caused by the improper use of the monitors. The solution to this problem is to use monitors with good resolution and fitted with an antiglare screen that filters excess light. A computer user at all times must adjust the brightness of the screen to the intensity that is comfortable to the eyes. Electromagnetic emissions Electromagnetic field emissions are waves of electrical and magnetic energy that are emitted by current carrying conductors. Computer users are advised to use low emission devices in order to avoid exposing themselves to excess emissions. Environment issues Some of the environmental effects of information and communication technology include energy consumption and radiation, pollution, paper consumption and disposal. Energy consumption and radiation Initially computers consumed a lot of energy thereby generating a lot of heat and emitting electromagnetic radiations. However in recent years, the Environmental Protection agency (EPA) launched energy star policy to encourage minimal use of power by electronic devices. Electronic devices have to be energy star compliant to be recognised under this policy. You can tell whether your computer complies to EPA if it displays the star during boot up   Environmental pollution Information technology has also contributed to environmental pollution. For example, huge garbage dumps of dead computer parts, printers, ink toner cartridges, monitors and other computer accessories are disposed in landfills hence causing environmental pollution. There has been concern on the disposal of Nickel – Cadmium laptop batteries that contain toxic cadmium which when buried in a landfill can leak into underground water tables and catchments areas. Cultural effects The rapid growth of information technology does not only provide us with different ways of working, playing and thinking but also presents challenges to our moral and cultural values. It is the moral standards that help in guiding human behavior. Information and communication technology has changed the way we talk, affected our privacy, human rights and integrity. For example Internet users are exposed to a form of communication called flaming. Flaming is writing on-line messages that use derogatory, obscene or of dirty language. Also through the Internet, one can view pornographic materials that affect moral values negatively. These free flows of immoral information have negatively influenced the behaviour of both the young and old in the society. Computer related crimes such as hacking, eavesdropping, piracy are on the increase. This has

Introduction Computers play an important role in every aspect of our society today. Hardly does a day pass without one coming across a computer system that is used in offering services that were initially done manually. In this chapter, we shall look at how computers have been applied in the contemporary society to add value to the information systems of various organizations. An information system is a collection of specific human and machine efforts required to support the decision making process, data processing, information output and presentation.   Application areas of information and communication technology Information and communication technology (lCT) has been applied in various areas such as in the development of financial systems, retail systems, reservation systems, educational systems, communication systems, industrial systems, scientific and research systems, library systems, entertainment systems, transportation systems, home use, office expert systems, marketing, virtual reality systems and law enforcement systems.   Financial systems Financial systems enable organisations to manage their finances. They include: Payroll systems. Accounting systems. Banking systems.   Payroll systems The primary purpose of this system is to process the accurate information of employees including gross pay, deductions and the net pay. Because money spent on human resource is one of the largest operating expenses of a business, a payroll system is also designed to produce several analysis reports e.g. a breakdown of payroll expenses against production/income of the company. Accounting systems Accounting systems are popular in business management. There are six key business accounting activities/subsystems: 1. Customer order entry and billing Inventory management General ledger accounting Accounts receivable Accounts payable Customer orders entry and billing Customer orders entry and billing subsystem records incoming customer orders, authorises delivery of items or services ordered and produces invoices for customers who do not pay in advance or on cash basis. Inventory management Inventory management is used to keep track of the items in stock and help the management determine which items to reorder. This helps the management to have enough stock at all times to meet the needs of the customers. General ledger accounting General ledger accounting is used to keep track of how much a business makes and its worthiness by summarising the financial transactions. It produces reports on income, sources of income, expenses, and the net profit or loss earned. A summary report of these transactions is called a balance sheet and is usually generated at the end of an accounting period. Accounts receivable Accounts receivable system keeps track or records of the amount owed by each customer. This helps the management to make a follow-up by billing the customers for overdue payments. Accounts payable Accounts payable system keeps track of the amount the business owes others e.g. suppliers, tax organisations, transport e.t.c. Hence, it helps the management to produce cheques for payment of these amounts.   Banking systems The banking industry was one of the earliest consumers of information and communication technology. The computerised banking services include: Processing customer transactions. Cheque clearing and processing. Electronic funds transfer. Processing customer transactions Computers are used in banks to carry out financial transactions such as recording deposits, withdrawals and calculating interests on savings and loans. Such systems also generate reports on the current status of accounts. In most banks, these transactions are entered via terminals, which are connected, to a central computer for centralised processing. The tellers have revolutionised banking activity by offering 24 hour service to customers and more flexibility in cash deposits and withdrawals. Cheque clearing and processing Computerised cheques clearing and processing is made possible due to the special characters on cheques printed using ink containing magnetic particles. The characters identify the bank in which the cheque is drawn, the customer account number, the cheque number and the amount of the cheque. Using a magnetic ink character reader, these details are automatically entered into a computer for cheque processing. Manual processing used to take lots of time but with computer systems, millions of cheques are processed every day hence improving efficiency in service delivery to customers. Electronic funds transfer (EFT) Electronic Funds Transfer (EFT) is the movement of money using information and communication technology. When a cash dispenser is used, the amount withdrawn by a customer is deducted from his/her account. Another example is when paying for goods and services using a credit card. Payment is transferred electronically from the customers account to the recipients account. Retail systems Computers are becoming more and more popular in retail stores such as supermarkets, distributor outlets etc. Computers are used in such stores for: Stock control Transactions handling at the electronic point of sale terminals (EPOS) Stock control A computerised stock control system enables a user to manage his/her stock more efficiently. This system is used to track what is in stock and what needs reordering so as to reduce the risk of under stocking or overstocking. Overstocking ties up valuable space and capital that could have been used for other valuable items. On the other hand under stocking causes customer dissatisfaction.   Transactions handling at the electronic point of sale terminals An electronic point- of -sale (EPOS) is a computer terminal used in retail stores to input and output data at the point where sales are transacted e.g. at the supermarket checkout counter. An EPOS terminal has all facilities of a normal cash register, but with additional direct data capture devices, e.g. bar code reader, card reader, a monitor and a receipt printer. In such retail stores, goods are identified by means of bar codes. For each item, a record is stored in secondary storage medium containing: the item number, item name or description, quantity in stock and the price. Transactions at the point of sale terminal may involve the following steps: The bar code reader (wand) is passed over the items bar code. The bar code is automatically converted to the item number, e.g. 2160, which is read to the computer. Using this number, the computer searches for the item with a corresponding number in the products database. Once the

Definition of terms used in networking. A computer network can be defined as a collection of computers linked together using transmission media for the purpose of communication and resource sharing. The term transmission media refers to any physical or non-physical link between two or more computers and in which a signal can be made to flow from source to destination. Some of the shared resources include programs, printers,storage devices, communication links etc. Data communication Data communication refers to the process of transmitting data signal from one point to another through the network. If all aspects related to data communication are taken into consideration, computer networking is the most recent, efficient and reliable means of transmitting data.   Terms used in data communication Some of the terms used in data communication include: data signal, signal modulation and demodulation, multiplexing, bandwidth, base band, broadband transmission and attenuation. Data signal: A data signal is a voltage level in the circuit which represents the flow of data. In data communication, data signals can either be analog or digital in nature. Analog data is made up of continuous varying waveform while digital data is made up of a non-continuous discrete waveform. Signal modulation and demodulation: This is the process of converting data signals to a form that is suitable or transmission over a transmission medium. For example, a modem converts a digital signal to analog by superimposing it on an analog carrier signal which can be transmitted over analog telephone lines. This process is called modulation. A modem at the receiving end converts the analog signal into digital form, a process known as demodulation. Multiplexing: Multiplexing is the process of sending multiple data signals over the same medium e.g. a wire conductor can be made to carry several data signals either simultaneously or at different times. Demultiplexing is the process of separating the multiplexed signals at the receiving end. Imagine a situation where one hundred computers in town A want to communicate with others of equal number in town B. If multiplexing is not used, each of the computers in town A will need a direct cable linking it to its partner in town B! However, with multiplexing, the computers can be made to share a single cable laid between the two towns hence save cost. The different frequencies create what is called different logical channels in the medium. . Bandwidth: A bandwidth is the maximum amount of data that a transmission medium can carry at anyone time. For example, a certain cable may have a bandwidth of 100 Mbps (Mega bits per second). Baseband signal: Baseband signal is a digital signal that is generated and applied to the transmission medium directly without modulation. The signal takes the form of voltages of different magnitudes applied to the medium. The baseband signal utilises the full capacity of the transmission medium, hence at anyone time; only one signal can be sent. However, multiple signals can be sent at different times if they are multiplexed. Broadband transmission: In broadband transmission, an analog signal is sent over the transmission medium using a particular frequency. This means that several data signals can simultaneously be sent through the same medium but at different frequencies. Frequency bands between these data signals prevent them from overlapping. Attenuation: This is the decrease in magnitude and energy as a signal progressively moves along a transmission medium. If the signal is not boosted, it will totally be .lost along the way and may never reach the destination. Attenuation or signal loss is usually corrected by placing signal amplifiers also called repeater stations along the medium at appropriate distances in order to receive the weak signal, clean it, amplify it then retransmit it.   Modes of data communication There are three modes of data communication namely: simplex, half Duplex and full duplex.  Simplex transmission refers to communication in only one direction. An example of simplex communication is the normal radio or television broadcast. The listener or viewer cannot communicate back through the radio or television receiver back to the broadcaster. Half duplex refers to communication in both directions but one direction at a time. A sender must send the data before the recipient can reply. For example, if two police officers are communicating using a ‘walkie talkie’ radio, one has to say “over” to mark the end of every statement in order for the other to respond. Full duplex communication occurs in both directions simultaneously. An example of full duplex communication can be found in computers that are sending and receiving data on a network. Types of computer networks Computer networks can be classified using several aspects but the most common classification is according to size. Currently, there are several types of networks but the three most common are: Local area network (LAN) Metropolitan area network (MAN) Wide area network (WAN) Local area network (LAN) Local area network is a computer network that spans a relatively small geographical area like in one building or a school. One local area network can be connected to other local area network over any distance via data transmission lines or wireless media. Most local area networks connect personal computers and server computers on a small network. A server computer is a computer dedicated to servicing requests for resources from other computers (workstations) on a network. Most local area networks are configured such that each workstation has its own central processing unit with which it executes programs, but it is also able to access data and devices anywhere on the local area network. Local area networks enable many users- to share expensive devices, such as laser printers, as well as data. Users can also use the local area network to communicate with each other, by sending messages or engaging in chat sessions. Local area networks are capable of transmitting data at very fast rates, much faster than data transmitted over telephone lines. .   Metropolitan area networks (MAN) A metropolitan area network is a network that covers a metropolitan area like

TOPIC 1 : INTRODUCTION TO NETWORKING AND DATA COMMUNICATION – Click to view TOPIC 2 : APPLICATION AREAS OF INFORMATION AND COMMUNICATION TECHNOLOGY – Click to view TOPIC 3 : IMPACT OF INFORMATION AND COMMUNICATION TECHNOLOGY (ICT) ON SOCIETY – Click to view TOPIC 4 : CAREER OPPORTUNITIES IN INFORMATION AND COMMUNICATION TECHNOLOGY – Click to view TOPIC 5 : DEVELOPING A PROJECT USING MICROSOFT ACCESS DATABASE – Click to view TOPIC 6 : DEVELOPING A PROJECT USING VISUAL BASIC PROGRAMMING LANGUAGE – Click to view

Introduction In the previous chapter, we studied how to develop a system using some system analysis and design methods without necessarily referring to any particular programming language. Therefore, we have been looking at what a system analyst ought to do rather than how a particular task should be done. In this chapter, we shall learn how to develop programs using Visual Basic programming language. Note that any other programming language can be used to develop programs. Therefore, as a leaner, you are at liberty to select any other programming language and learn how to use it to construct systems. Definition of Visual Basic Visual Basic (VB) is a graphical user interface programming language for creating software systems that run under Microsoft Windows environment. It is modeled in line with BASIC language which was originally created to help students learn how to program. Visual Basic has the following features: It is an event driven programming language. An event is a response generated by the program when the user performs an action e.g. a mouse click. The response depends on the code held in an event procedure. An event procedure is a group of self contained statements that are executed by the computer when a trigger action is performed. For example, a mouse click may cause a menu to be displayed on the screen. It has a collection of tools that are used by programmers. These tools are called The controls can be accessed easily by clicking their icons on the toolbox to select them. It has special objects called forms that have a title bar at the top. The programmer can then add controls such as a menu bar, status bar, toolbars, buttons, and slide bars to the form when creating an application. Starting Microsoft Visual Basic You can start Visual Basic from the Programs menu by pointing to Microsoft Visual Studio and then selecting Microsoft Visual Basic. Depending on the way the application has been setup, you may see the New Project dialog box This dialog box allows you to set up a new project. You can set up several types of projects as shown by the different icons in this dialog box. However, for the purposes of learning, let us select the Standard.EXE project found on the New tab. Click the Open button. The application window will appear. This is the Visual Basic Integrated Development Environment (IDE). Features of Visual Basic Integrated Development Environment (IDE) window The Visual Basic application window (Figure 5.2) has many similarities to common windows based applications. The following is a summary of the various features identified in the window: The standard toolbar Like in many other applications, the standard toolbar has the standard icons that are shortcut commands to the menu bar commands. Simply point to an icon and a text tip will appear telling you the name of the icon. Of great interest to us this time are the three commands of Start, Break and End. To execute a Visual Basic project, simply click the Start button or select Start1from the Run menu. Execution of the program can be temporarily suspended by clicking the Break button. Resume the run by selecting Continue from the Run menu. Finally, the execution can be stopped by clicking the End button. Forms and controls Forms and controls are generally called objects. An object is usually associated with an event hence most objects have their own properties and methods. The properties define the appearance of the object while the method is a predefined action that can be set to occur or affect the object. For example show method makes a form visible on the screen. The form design window is the place where the programmer does the actual design of the user interface for the program. This is accomplished by selecting the relevant control icons from the toolbox then placing them on the form design window. The control can then be moved and resized as desired by the programmer. The entire form can be moved around on the screen by holding the title bar of the project container window then dragging it to the required position. Project window The project window displays a hierarchical list of files associated with a particular project. The files represent forms and program modules in the project. For example, Figure 5.2 shows a form whose title is Form 1. Properties window The properties window displays a set of various characteristics unique to each active object in the project. Some examples of properties include name, caption, colour, height etc. When a new project starts, it is most likely that the form design window is active. In this case, the properties for the form will be displayed and can be changed by the programmer as appropriate. For example, we can change the caption of the form by clicking on the Alphabetic tab in the properties window then changing the value associated to Caption property from Form.l to say “Book Data Form”. Notice that the caption in the title bar of the active form changes simultaneously as you type the new name in the properties window. Code editor window Figure 5.2 shows that the project window has three icons at the top left hand comer. One of them is called the code view icon. Point to the icon with the mouse pointer and a tool tip will appear showing its name. If you click it, the code editor window opens displaying the code of the object that is currently selected. Alternatively, double click the object on the form for which you want to edit its code. The code editor window will open (Figure 5.4). In this case, we double clicked the form. Form layout window The form layout window allows you to specify the screen location of the form when the project is Executed. This can be done by dragging the form in this window to the desired location. The Visual Basic toolbox Visual Basic tool box has controls that enable a person to design

Introduction The concept of a system emerged from early psychologists who believed that the mind was a whole unit, rather than a collection of psychological parts as the belief was by that time. However, it was Ludwig von Bertalanff, a German biologist, who gave the name “general systems theory” to the discipline that devoted itself to coming up with principles that apply to all systems. A system is a set of organised components which interact in a given environment and within a specified boundary to achieve collective goals and objectives that are emergent. Emergent characteristics are those that result from interaction of various components and may not exist in the individual component. Therefore, once the components come together, they become interrelated and generate new goals and objectives. For example, a bicycle system has all the components working together to provide motion when ridden. The individual components cannot provide these services to a rider when on their own!   Description of a system A system can be described as being either soft or hard. Soft systems Human activity systems are said to be soft systems. They are described as soft because of three main reasons: Their boundaries may be fluid or keep on changing. Their goals and objectives usually conflict and may not be captured clearly at anyone time because they are based on human factors like attitudes and preferences. It is difficult to precisely define exact measures of performance for them. One example of a soft system is the political system. It is very difficult for instance to model a system that will predict the political mood in a country over a period of time. Another example is a sales tracking and prediction system in an organisation. Sales in an organisation depend on human factors like attitude in the market place. Hard systems Hard systems are systems whose goals and objectives are clearly defined and the outcomes from the systems processes are predictable and can be modeled accurately. Such systems are based on proven scientific laws like mathematical formulas or engineering solutions. An example of a hard system would be a stock management system in a supermarket. It is possible to know exactly the stock levels, cost and sale price and to predict accurately the profit if all the stock is sold. A good system incorporates both hard and soft aspects of a system. For example, a stock management system should be able to show when the demand for a certain item rises so that a decision can be made to stock more. New demand is driven by soft aspects in people’s lives like attitude and seasons! Characteristics of systems All systems have some common characteristics. Some of these characteristics are explained below. Holistic thinking In holistic thinking a system is considered as a whole. Aristotle, a Greek philosopher, once said that the whole is more than the sum of the parts. The various components that make up a system may be simple in nature and process but their combination creates a complex whole, whose overall goals are more sophisticated than those of the individual components. Hence, a system should be considered as a whole unit rather than considering its parts individually.   Subsystems A system is made up of different components (subsystems). Therefore a system does not exist in solitude but it may be a component of larger a system. For example, the classroom system is part of a school system, which is part of the Ministry of Education. The Ministry of education is part of the Government which is part of the global system! Boundary and environment Each system has a space (boundary) within which the components operate. Any entity that falls outside the boundary but interacts with the system is part of the system environment. Such entities are called external entities. They provide the inputs and receive the outputs from the system. For example, the external entities to a school system may include the parents, various suppliers and the society at large. Purpose The purpose of each system is to perform a particular task or achieve a goal. The objectives that a system is supposed to achieve enable system developers to measure the performance of a system during its operation. One main objective for a school system for instance is to enable the students to excel in national examinations. Process A system usually will transform or process data from one state to another. System entropy The word entropy means decay. Systems “decay” naturally over time. This means that a system slowly becomes useless to the user either due to improvement in technology, new management policies or change in user requirements. Therefore a system must be reviewed in order to improve it or to develop a new one. Inputs and outputs A system communicates with its environment by receiving inputs and giving outputs. For example, a manufacturing firm can be considered as a system that gets raw materials (inputs) from the environment and transforms them into finished products (outputs) released into the environment. Open and closed systems A system can be described as being open or closed. An open system receives input from and gives output to the environment while a closed system does not. Open systems normally adapt to changes in the environment. Control Control can be defined as the method by which a system adapts to changes in the environment in order to give the expected output or to perform to the expected level. Control is achieved through feedback which involves having outputs from the process of the system being fed back to the control mechanism. The control mechanism in turn adjusts control signals that are fed to the process which in turn makes sure that the output meets the set expectations. Fig. 4.1 depicts a typical system that has feedback to the control function. Imagine a motor vehicle manufacturing company that is producing several vehicles per day. Assuming that the demand rises, then feedback would show that the company is underperforming. Hence, control signals

Introduction Human beings have evolved from the Stone Age to a highly sophisticated and advanced society by inventing things like the wheel, fire, transistors and today’s ultra modem devices like computers. The idea of computers started way back in the nineteenth century. The first generation computers called Electronic Numeric integrator and Calculator (ENIAC 1) were operated by plugging wires into a control panel that resembles the old telephone switchboards Computer programming A computer works by executing a set of instructions known as a program. The term programming refers to the process of developing computer instructions (programs) used to solve a particular task. It involves use of special characters, signs and symbols found in a particular programming language to create computer instructions. A programming language is a special set of symbols that can be translated into machine-readable form by the computer when arranged in a particular sequence or order. Each language has a special sequence or order of writing characters usually referred to as syntax. It was John von Neumann of Princeton University (USA) who first came up with the proposition to store programs in the computer memory. Perhaps, this was one of the most dramatic developments in the computer history. Why? Because not only did the new stored-program way of computing increase-processing speed but also allowed easy and flexible methods of editing and updating the program.   Description of terms used in programming Before we go further with programming, it is important to define some common terms used in computer programming.   Source program The term source program refers to the program code that the programmer enters in the program editor window that is not yet translated into machine-readable form. The source program is usually created using a particular programming language as discussed later.   Object code The term object code refers to the program code that is in machine-readable. A source code that is not in machine-readable form must be translated into object code.   Translators The term translator is used to refer to language processors such as assemblers, interpreters and compilers that convert the source program into object code.   Assembler An assembler translates assembly language into machine language that the computer can understand and execute.   Interpreter An interpreter translates the source program line-by-line, allowing the CPU to execute one line before translating the next. The translated line is not stored in the computer memory. It means that every time the program is needed for execution, it has to be translated. This method of translating programs was very common in early computers that did not have enough memory to store the object code as a file that can be executed later   Compiler A compiler translates the entire source program into object code: The object code file can be made into a fully executable program by carrying out another process known as linking which joins the object code to all the other files that are needed for the execution of the program. After the linking process, an executable file (application file) is generated. This file is stored on a storage media such as a disk with a name that has a unique extension (.EXE). Examples of executable files are WINWORD.EXE and PM70.EXE used to start Microsoft Word and Adobe PageMaker 7.0 respectively.   The difference between the interpreters and compilers are summarised below: Levels of programming languages Many programming languages have been developed over the years. These languages are classified into two major levels namely: Low-level languages High-level languages These levels are further subdivided into five generations. The first and second generations consist of low-level languages while the third to the fifth generation consist of high-level languages.   Low-Level languages Low-level languages are classified as low because the computer can easily understand them directly or they require little effort to translate into computer understandable form. These languages are hardware oriented and therefore they are not portable i.e. a program written for one computer cannot be installed and used on another. Two types of low level languages are the machine languages and assembly languages.   Machine languages (First generation languages) In machine languages, instructions are written using binary logic. Given that data and instructions are in binary form, many lines of code are needed to accomplish even a simple task like adding two numbers. A program written in machine language might look like this: It is evident from the above code that it is hard for a person to guess what the program is all about unless they have special knowledge in machine level programming. Furthermore, different CPU’s have different machine codes e.g. those for the Intel Pentium processors may differ from Motorola or Cyrix processors. Therefore before decoding the meaning, a programmer has to know for which CPU the program was written. Obviously, such programs are hard to understand from the programmer’s point of view, but very easy to execute from the computer’s perspective.   Assembly languages (Second generation languages) Assembly languages were developed in order to overcome the difficulties of understanding and using machine languages. These languages represented the first successful attempt to make computer languages readable. The languages allowed programmers to write programs as a set of symbolic operation codes called mnemonics. Mnemonics are basically shortened two or three letter words.  Programs written in assembly language require an assembler in order to convert them into machine language that the computer can understand. Just like the machine languages, assembly languages are also machine dependent and therefore a program written for one computer cannot be used on another.   High-level languages High-level languages are very close to the human language (English like) and they can be read and understood even by people who are not experts in programming. There are many types of high-level languages and each of them was developed to address a particular problem-solving domain while others came about due to advancement in technology. These languages are machine independent. This means that a programmer concentrates on problem solving during a programming session rather than