December 14, 2022

Introduction Data refers to the raw facts that do not have much meaning to the user and may include numbers, letters, symbols, sound or images. Information, on the other hand, refers to the meaningful output obtained after processing the data. Therefore the data processing refers to the process of transforming raw data into meaningful output i.e. information. Data processing can be done manually using pen and paper, mechanically using simple devices like typewriters or electronically using modem data processing tools such as computers. Electronic data processing has become so popular that manual and mechanical methods are being pushed to obsolescence. Data processing cycle Data processing cycle refers to input-process-output stages that data goes through to be transformed into information. It is often referred to as a cycle because the output obtained can be stored after processing and may be used in future as input. The four main stages of data processing cycle are: Data collection Data input Processing Output   Data collection Data collection is also referred to as data gathering or fact-finding. It involves looking for crucial facts needed for processing. Methods of data collection Some methods of data collection include interviews, use of questionnaires, observation etc. In most cases, the data is collected after sampling. Sampling is the process of selecting representative elements (e.g. people, organisations) from an entire group (population) of interest. Some of the tools that help in the data collection include source documents such as forms, data capture devices such as a digital camera etc. Stages of data collection The process of data collection may involve a number of stages depending on the method used. These include: Data creation: This is the process of putting together facts in an organised format. This may be in form of manually prepared document or captured from the source using a data capture device such as a bar code reader. Data transmission: This will depend on whether data need to be transmitted via communication media to the central office. Data preparation: This is transcription (conversion) of data from source document to machinereadable form. This may not be the case for all input devices. Data collected using devices that directly capture data in digital form do not require transcription. Media conversion: Data may need to be converted from one medium to another e.g. from a floppy disk to hard disk for faster input. Input validation: Data entered into the computer is subjected to validity checks by a computer program before being processed to reduce errors at the input. Sorting: In case the data needs to be arranged in a predefined order, it is first sorted before processing.   Data input Data input refers to a process where the collected data is converted from human readable form to machine-readable form (binary form). The conversion takes place in the input device. Processing This is the transformation of input data by the central processing unit (CPU) to a more meaningful output (information). Some of the operations performed on data include calculations, comparing values and sorting. Output The final activity in data processing cycle is producing the desired output also referred to as information. The information can then be distributed to the target group or stored for future use. Distribution is making the information available to those who need it and is sometimes called information dissemination. This process of dissemination may involve electronic presentation over radio or television, distribution of hard copies, broadcasting messages over the Internet or mobile phones etc.   Description of errors in data processing The accuracy of computer output is very critical. As the saying goes, garbage in, garbage out (GIGO), the accuracy of the data entered in the computer directly determines the accuracy of the information given out. Some of the errors that influence the accuracy of data input and information output include transcription, computation and algorithm errors.  Transcription errors Transcription errors occur during data entry. Such errors include misreading and transposition errors. Misreading errors Incorrect reading of the source document by the user and hence entering wrong values bring about misreading errors. For example, a user may misread a hand written figure such as 589 and type S86 instead i.e. confusing 5 for S. Transposition errors Transposition errors results from incorrect arrangement of characters i.e. putting characters in the wrong order. For example, the user may enter 396 instead of369. Transcription errors can be avoided by using modem data capture devices such as bar code readers, optical character readers, and digital cameras etc., which enter data with minimum user intervention. Computational errors Computational errors occur when an arithmetic operation does not produce the expected results. The most common computation errors include overflow, truncation and rounding errors.  Overflow errors An overflow occurs if the result from a calculation is too large to be stored in the allocated memory space. For example if a byte is represented using 8 bits, an overflow will occur if the result of a calculation gives a 9-bit number. Truncation errors Truncation errors result from having real numbers that have a long fractional part that cannot fit in the allocated memory space. The computer would truncate or cut off the extra characters from the fractional part. For example, a number like 0.784969 can be truncated to four digits to become 0.784. The resulting number is not rounded off. Rounding errors Rounding errors results from raising or lowering a digit in a real number to the required rounded number. For example, to round off 30 666 to one decimal place, we raise the first digit after the decimal point if its successor is more than 5. In this case, the successor is 6 therefore 30.666 rounded up to one decimal place is 30.7. If the successor is below 5, e.g. 30.635, we round down the number to 30.6. Algorithm or logical errors An algorithm is a set of procedural steps followed to solve a given problem. Algorithms are used as design tools when writing programs. Wrongly designed programs would result in a program that runs

Introduction In Book 1 of this series, we learnt that computers are classified according to functionality, physical size and purpose. We saw that when classified according to functionality, computers can be analog, digital or hybrid. Digital computers process data that is in discrete form while analog computers process data that is continuous in nature. Hybrid computers, on the other hand can process both discrete and continuous data. In digital computers, the user input is first converted and transmitted as electrical pulses that can be represented by two distinct digits’ l’ and ‘0’ before processing. These two digits are referred to as binary digits or in short bits. Although two graphs can look different in their appearance, they may repeat themselves at equal time intervals. Electronic signals or waveforms of this nature are said to be periodic. Generally, a periodic wave representing a signal can be described using the following parameters. Amplitude (A) Frequency (f) Periodic time (T)   Amplitude (A): Amplitude is the maximum value a wave can attain. For example, the amplitude of waves in Figure 1.1 is 1. Frequency (f): Frequency of a wave is the number of cycles made by the wave in one second. It is measured in units called hertz (Hz). 1Hz is equivalent to 1 cycle/second. Periodic time (T): The time taken by a signal to complete one cycle is called periodic time. Periodic time, T, is given by the formula T = 1/f where f is the frequency of the wave. When a digital signal is to be sent over analog telephone lines e.g. e-mail, it has to be converted to analog signal. This is done by connecting a device called a modem to the digital computer. This process of converting a digital signal to an analog signal is known as modulation. On the receiving end, the incoming analog signal is converted back to digital form in a process known as demodulation. Concepts of data representation in digital computers Since digital computers are the most widely used, this book seeks to explain in details how data is represented in digital form. Data and instructions cannot be entered and processed directly into computers using human language. Any type of data be it numbers, letters, special symbols, sound or pictures must first be converted into machine readable form i.e. binary form. Due to this reason, it is important to understand how a computer together with its peripheral devices handle data in its electronic circuits, on magnetic media arid in optical devices.   Data representation in electronic circuits Electronics components, such as the microprocessor, are made up of millions of electronic circuits. The availability of a high voltage (on) in these circuits is interpreted as ‘I’ while a low voltage (off) is interpreted as a ‘0’. This concept can be compared to switching on and off of an electric circuit. (Figure 1.3). When the switch is closed, (Figure 1.3 (a)), the high voltage in the circuit causes the bulb to light (‘ l’ state). On the other hand, when the switch is open (Figure 1.3 (b)), the bulb goes off (‘0’ state).   Data representation on magnetic media The presence of a magnetic field in one direction on magnetic media is interpreted as ‘I’, while the field in the opposite direction is interpreted as ‘0’. Magnetic technology is mostly used on storage devices which are coated with special magnetic materials such as iron oxide. Data is written on the media by arranging the magnetic dipoles of some iron oxide particles to face in the same direction and some others in the opposite direction. Figure 1.4 shows how data is recorded on the surface of a magnetic disk. Note that the dipoles on the track are arranged in groups facing opposite directions.   Data representation on optical media In optical devices, the presence of light is interpreted as ‘1’ while its absence is interpreted as ‘0’. Optical devices use this technology to read or store data. Take an example of a CD-ROM. If the shiny surface is placed under a powerful microscope, the surface can be observed to have very tiny holes called pits. The areas that do not have pits are called land (Figure 1.5). In Figure 1.5 (a) the laser beam reflects from the land which is interpreted as ‘1’ while in Figure 1.5 (b) the laser beam enters a ‘pit’ and is not reflected. This is interpreted as ‘0’. The reflected pattern of light from the rotating disk falls on a receiving photoelectric detector that transforms the patterns into digital form.   Reason for use of binary system in computers It has proved difficult to develop devices that can understand or process natural language directly due to the complexity of natural languages. It is, however, possible to develop devices that can understand binary language. Devices that read, process and output data in digital form are used in computers and other digital devices such as calculators. Binary logic has therefore simplified the technology needed to develop both hardware and software systems. Other reasons for the use of binary are that digital devices are more reliable, small in size and use less energy as compared to analog devices.   Bits, bytes, nibble and word The terms bits, bytes, nibble and word are used widely in reference to computer memory and data size. Let us explain each term. Bits: A bit can be defined as binary digits that can either be 0 or 1. It is the basic unit of data or information in digital computers. Byte: A group of bits (often 8) used to represent a character is called a byte. A byte is considered as the basic unit of measuring memory size in computers. A nibble: Half a byte, which is usually a grouping of 4 bits is called a nibble. Word: Two or more bytes make a word. The term word length is used as a measure of the number of bits in each word. For example a word can have a length

TOPIC 1 : DATA REPRESENTATION IN A COMPUTER – Click to view TOPIC 2 : DATA PROCESSING – Click to view TOPIC 3 : ELEMENTARY PROGRAMMING PRINCIPLES – Click to view TOPIC 4 : SYSTEM DEVELOPMENT – Click to view TOPIC 5 : PROGRAMMING WITH VISUAL BASIC – Click to view

6.1 Introduction and definition Computer information systems are becoming more and more important in daily life. Governments, private enterprises and individuals have found the need to protect data and information that is in their custody against unauthorized access, disclosure or damage. This is because of the rise of the information age and society leading to the subsequent view of information as a scarce valuable resource. This has posed threats to data and information both from known and unknown sources. Data and information security Data security involves: Protection of data and information against unauthorized access or Modification. Denial of data and information to unauthorized users. Provision of data and information to authorized users. Data security also includes all the measures that will be taken to detect, document and counter the threats to data and information.   Data and information privacy Private data or information is that which belongs to an individual and must not be accessed by or disclosed to any other person unless with direct permission from the owner. On the other hand, the data or information held by a government or organization about people is confidential data. This data and information may be seen by many authorized persons without the knowledge of the owner. However, it should not be used for commercial gain or any other unofficial purpose without the owner being informed. This data must also be protected against unauthorized access or disclosure.   6.2 Security threats and control measures  Viruses A computer virus is a destructive program that attaches itself to other files and installs itself without permission on the computer when the files are opened for use. The virus may cause havoc on the computer system, for example, it may delete data on storage devices or interfere with the proper functioning of the computer system. Types of computer viruses include: Boot sector viruses – they destroy the booting information on storage devices. File viruses – attach themselves to files. Hoax viruses – Come as e-mail with an attractive subject and launches itself when e-mail is opened. Trojans – they appear to perform necessary functions but perform other undesirable activities in the background without user knowledge. Worms – viruses that stick in the computer memory. Backdoors – may be a Trojan or a worm that allows hidden access to a computer system. Control measures against viruses Install the latest versions of anti-virus software on the computers. Make sure that you continuously update the anti-virus software with new virus definitions to counter the new viruses that are being manufactured on a daily basis. Avoid foreign diskettes in the computer room. If they have to be used, they must first be scanned for viruses. Avoid opening mail attachments before scanning them for viruses.   Unauthorized access Data and information is always under constant threat from people who may want to access it without permission. Such persons will usually have a bad intention either to commit fraud, steal the information and ­destroy or corrupt the data. Unauthorized access may take the following forms:   Eavesdropping This is tapping into communication channels to get information. Hackers mainly use eavesdropping e.g. to obtain numbers of credit cards.   Surveillance (monitoring) This is where a person may keep a profile of all computer activities done By another person or people. The information gathered may be used for one reason or the other e.g. spreading propaganda or sabotage. Many websites keep track of your activities using special programs called cookies.   Industrial espionage Spying on your competitor to get information that you can use to counter or finish the competitor. This is mostly done with an aim to get ideas on how to counter by developing similar approach or sabotage. Also unauthorized access can be as follows: An employee who is not supposed to view or see sensitive data by mistake or design gets it. Strangers who may stray into the computer room when nobody is using the computers. Forced entry into the computer room through weak access points. Network access in case the computers are networked and connected to the external world. Control measures against unauthorized access Enforce data and information access control policies on all employees. Encrypt the data and information during transmission (data encryption is discussed in details later in the chapter). Keep the computer room closed when nobody is using it. Reinforce the weak access points like doors and windows with metallic grills and burglar alarms. Enforce network security measures. Use files passwords to deter any persons who may get to the electronic files. Computer errors and accidental access Sometimes, threats to data and information come from people making mistakes like printing sensitive reports and unsuspectingly giving them to unauthorized person(s). Also, if end users have too much privilege that allows them to change or access sensitive files on the computer then accidental access mistakes may occur. Errors and accidental access to data and information may be as a result of people experimenting with features they are not familiar with. For example, a person may innocently download a file without knowing that it is self-installing and it is dangerous to the system.   Control measures against computer errors and accidents Give various file access privileges and roles to the end users and technical staff in the organization i.e. denies access permissions to certain groups of users for certain files and computers. Set up a comprehensive error recovery strategy in the organization.   Theft The threat of theft to data and information is a real one. Some information is so valuable that business competitors or some governments can pay a fortune to somebody who can steal the information for them to use. Therefore the following control measures should be taken to prevent theft of hardware, software and information.   Control against theft Employ guards to keep watch over data and information centers and Backups. Burglar proofs the computer room. Reinforce weak access points like the windows, door and roofing With metallic grills and strong padlocks. Create backups in locations away

Introduction Computers can be connected together using data transmission media like cables, to communicate with one another. Communication in this case will be in the form of exchange of data and information. Such interconnection of computers to achieve message transfer is called networking. This is because the computers are linked to form a net.  In most cases computer networks are unique to an organization. For example the computers in your computer laboratory may be networked. Such a network is local in nature hence it is usually called a local area network (LAN).  Definition of the Internet The term Internet can be broken down into two words, inter and net which implies that there is an interconnection of networks. Internet is therefore a large network of networks that covers the whole world and enables millions of computers from different organizations and people To communicate globally. Because of its large size and great volume of information that passes through it, it is sometimes called the information superhighway.  Because of the flexibility of Internet technology, many organizations are creating their own private networks using the technology of the Internet. In this book we shall refer to the Internet (with capital letter I) as the information superhighway and the internet (with lower case letter (i) to refer to smaller networks.   5.3 Development of the Internet In 1969, a research body in the USA called Advanced Research Projects Agency (ARP ) set up a computer network that connected four universities and was given the name ARPAnet. This network is viewed as the forerunner of today’s Internet. The aim was to allow sharing of data and information between computers. The main benefit was that there was fast communication between researchers through electronic mail or e-mail. ARPA’s goal was to allow multiple users to send and receive information at the same time. The network used a special data transmission technique called packet switching which was later adopted for the Internet. A computer would send a packet that contained data, destination address information, error detection control information and packet sequencing information. By 1973 e-mail was the most common service on the Internet. It was not until 1979 that the first media companies connected to the Internet. By 1981, many people had seen the importance of computer networking and the Internet. ARPAnet formed the backbone on which many organizations started connecting to, hence expanding it. The American military also became a big user of the Internet because they could communicate and tap into the resources available on the net. Next, the American Government decided to access the Internet for commercial purposes hence greatly increasing the traffic. By this time, for every twenty days, a new host computer was connected to the net. By 1987, the Internet boasted of 10 000 host computers. However, its access was largely limited to the United States of America and some nations in Europe. As the importance of the Internet grew, businesses spent billions of dollars to improve it in order to offer better services to their clients. Fierce competition arose among software and hardware manufacturers as they came up with new technology to meet internetworking needs. The result was a great increase in message transmission capacity (bandwidth) and it became cheaper to work with the Internet. By 1994, 3 million computers were connected to the Internet. Today, the Internet has grown and covered the whole world. Governments, private organizations and individuals are using the Internet in all spheres of daily life to send messages and conduct business.   Importance of Internet The Internet is an extensive system of interlinked yet independent networks. It has evolved from a specialised communication network previously only used for military and academic purposes to a public network that is changing the way people carry out their daily activities. The Internet is playing a very important role in all aspects of life, leading to the emergence of an elite society called the information society. The Internet’s importance can be between through its contribution to research, news and information dissemination, leisure and communication, a place to do business and many other profitable activities.   Internet connectivity requirements For a computer to be able to connect to the Internet, there are several requirements one of them is to connect to a telecommunication service provider in order to transmit data over a wide region. This section seeks to discuss some minimum requirements for Internet connectivity to be achieved.   Telecommunication facilities The Internet heavily relies on telecommunication facilities like the telephone lines, telephone exchange stations and satellite transmission in order to cover the whole wide world. Indeed, without these facilities, the Internet is as good as dead. Therefore, a computer is connected to the external world through a telephone line and has to dial a remote computer on the net to establish a connection for data transfer. Dial-up connections, however, are quickly being replaced by dedicated digital data transmission telephone lines called dedicated digital leased lines. A leased line connection ensures constant and quick connection to the Internet unlike the dial-up that you need to dial every time you need to access the Internet. Transmission of data on land takes the form of telephone exchange to telephone exchange until the data reaches the destination. However, intercontinental transfer of data is achieved by having satellite base stations transmitting g the data through a wireless uplink channel to the satellite. The satellite then sends the data signal to the base station on another continent where it is picked up and sent to telephone exchanges For transfer to the destination computer. Figure 5.1 shows a simple logical illustration of the Internet. Modems A computer needs a special digital to analog and vice versa interface card called a modem that enables it to send and receive data on telephone lines. Remember that voice transmission on telephone lines is analog in nature while computers work with digital data. However, digital telephone lines make it possible for computers to transmit and receive digital data without a

Introduction Have you ever asked yourself how newspaper and book publishing companies manage to produce publications that are attractive with creative layouts and graphics in large volumes? They do this through a special process called publishing. Publishing is the process of producing publications like newspapers, cards, pamphlets, pictures, calendars etc. that have special text and graphical layouts and designs. The traditional method of publishing involved drawing and writing manually on wooden or metallic boards. The artwork would then be painted with ink and pressed on papers to produce a printout. This was a very tedious work. Today the art of publishing has changed because of the advent of personal computers and smaller printers that are able to print high quality text and graphics even in an office or at home. Definition of desktop publishing (DTP) Desktop publishing refers to the process of producing publications like cards, newspapers etc. by designing their text and graphics layout and inserting, editing, formatting and printing of text and graphical objects using a special desktop publishing software installed on computers. The term desktop means that all the publishing processes can now be done on a desk in the office or at home using a personal computer! The difference between a desktop publisher and a word processor is that a desktop publisher software gives the user more tools and control of the page layout, text manipulation and graphic design than a word processor. However it is important to note that some word processors today have also been incorporated with text and graphic formatting and editing tools. Hence a thin line exists between them and the desktop publishers. For example you can design a full publication in Microsoft Word by using the available drawing and picture tools, create columns etc. Examples of desktop publishers include Adobe PageMaker, CorelDraw, Microsoft Publisher and Ventura. This book will use Adobe PageMaker to demonstrate the concepts of desktop publishing.   Purpose of desktop publishing software Desktop Publishing programs are very popular in publishing because they give the person designing publications (typesetter) a lot of control on: Graphic design: Using desktop publishing software, a typesetter can create and edit very complex text and graphical objects like pictures to the finest details. For example, the software provides the user with rulers and ruler guides that can be used to place an object in exactly the correct position. Page layout design: With a desktop publisher, the user can be able to design a page layout by setting consistent picture and object locations, dividing a page in a number of columns and creating layers. A layer can be viewed as the arrangement of objects on top of each other with the one on top being on the first layer e.g. text can be on one layer while graphical objects on another. Therefore the text layer can be manipulated separate from the graphical object layer like for example text moves separate from the objects. Another good example is you can make the graphical object layer transparent in order to make the text in a layer behind the object visible. Printing: Because the main purpose of any desktop publisher is to produce publication s, this cannot be accomplished without printing. Desktop publishing software therefore helps the user prepare what is referred to as an artwork in commercial circles for printing. Types of desktop publishing software There are two main types of desktop publishing software: Graphical based: They are specifically developed to edit and format graphic objects like pictures. Examples are Adobe Photoshop, Corel Draw, harvard graphic etc. This desktop publishers have superior image handling capabilities like setting resolution, brightness, contrast, cropping and filling images of all types with colour.   Layout based: These types of desktop publishers are specifically developed to create different page layout designs for text and pictures. Have you ever wondered how the complicated front page of a newspaper is developed? It is difficult to achieve such without a good layout based DTP. Good examples of layout based desktop publishers are Adobe PageMaker and Microsoft Publisher.   Designing a publication Publications vary in design and formatting. For example, a card has a particular design layout that is different from a newspaper. Therefore, publication designs determine how they are classified.   Types of publications It is possible to produce different types of publications using a desktop publishing software. There are several types of publications that can be published namely: Cards: These may be for weddings and other special occasions like graduations and for congratulations. Certificates: To show completion of courses and special events. These type of publications are very sensitive because they must be designed to discourage any type of duplication or counterfeits. Newspapers, magazines, pamphlets and newsletters: Have news targeting a group of people. They may have many text and graphical layouts and designs. Books: Are bulky publications with many pages bound together in the same publication. Calendars: Apart from showing dates, they are used by companies to advertise their products hence most of them have heavy catchy graphics.   Running Adobe PageMaker Currently PageMaker versions 6.5 and 7.0 are the most common desktop publishing software developed by Adobe PageMaker. Other Adobe products includes Adobe Photoshop mainly used for editing and formatting photographs, Adobe illustrator used for creating complex freehand artwork such as drawings and logos etc.   Starting Adobe PageMaker Click the Start button and then point to Programs From the programs sidekick menu, point to Adobe group then select PageMaker. Figure 4.1 shows how to start PageMaker in a typical Windows environment. The PageMaker program starts and provides the Document Setup dialog box. If the Document setup dialog box is not displayed, then click File menu and select the New command. In the Document Setup dialog box similar to the one in Figure 4.5 specify the publication setup options. Click OK to apply the selected options. A publication window similar to the one in Figure 4.2 is now displayed.   PageMaker screen layout                                                       . The PageMaker application window looks like most

Introduction to databases We are often faced with the need to keep, search for or give a report of daily experiences. This is the reason why many people use data storage methods like recording daily experiences in a diary. Traditionally, human beings used to manage data and information manually by using simple devices. However these methods have a number of weaknesses which include Unnecessary duplication of data Boredom and time wasting especially when searching for a Particular item. Misleading reports due to poor data entry and organisation Poor update of records etc. Today, computerized systems have radically changec4the way data and information is managed by use of special programs called Database Management System (DBMS).  A database is a collection of structured and related data items organised so as to provide a consistent and controlled access to the items.   Database concepts                                                                           . Computerised database creation and manipulation is achieved using Database Management System software. This software facilitates the creation, organisation and maintenance of databases. Examples of database management software’s include Microsoft Access (Ms Access), Oracle, FoxPro, Dbase/V, Lotus Approach etc. The functions of database management software are to: Allow the user add or delete records. Update or modify existing records. Organise data for easy access, retrieval and manipulation of records. Act as an interface between a database and other application programs. Ensure security for the data in the database by safeguarding it against unauthorized access and corruption (damage). Keep statistics of data items in a database. Database models Databases are classified according to the method used to organise data. The main database models are; Flat file 2. Hierarchical Network 4. Relational NB: Current database models are called object relational and object databases. However these models will not be discussed in details in this book.   Flat files  In a flat file model, a database holds only one set of data and is not any different from the manual files. For example, the teacher’s assessment report may consist of performance cards for every student in a class. Another example of a flat file database are the cards used in a library books catalogue. The cards are arranged sequentially for easy access e.g. alphabetically using books’ titles or by authors’ names. Figure 3.1 below is a sample record of a flat file. Hierarchical model In this model, data items are arranged in hierarchical (tree) form as shown in Figure 3.2. To access level two data items, you have to first access level 1 data items. Level 1 item is called the root component. A specific single path leads to each item at lower levels. Hierarchical model is rarely used in modem database systems. Network model  In this type of organisation, links are used to express the relationship between different data items, forming a network of items as shown in Figure 3.3. Access to one item can be through multiple paths and from any item. This model is also rarely used in modem database systems. Relational model This is the most common type of model used on minicomputers and microcomputers. In this type of organisation, related data items are stored together in structures called relations or tables. Relationship can be created between tables such that a record or records from one table relates to another or other records in another table. Tables 3.1 and 3.2 show customers and orders tables that are related by two fields; the customer number in Table 3.1 and customer ID in Table 3.2. In this case, the orders table shows that one customer with number 450 (Bat Hori) has made several orders. Object oriented models                                                                            . ! The next generation of database model will look at records as objects that are independent and relate with the other objects in the database. This concept is a bit difficult to conceptualise because such databases are still at developmental stage. However, many databases today combine object and relational concepts to come up with object relation models. Features of a database management software Most database software contains a collection of features that provides the user with a means to manipulate data in a database. These features include Tables/files, Queries, Reports generators, Form interface and a computer programming language within it. Microsoft Access database software that will be considered in this book has two distinct features used to automate operations namely Macros and Modules.   Tables/ file structure This is a database structure that is used to hold related records. Tables are organised in rows and columns with each row representing a record while each column represents common fields in each record. Table 3.3 shows a table of six records and each record is made up of four fields.   Queries and query language A query is a database tool used to search for or question a database on specific records. Because a query is a question posed to the database, it returns a result for the user. In Microsoft Access, this result is called a dynaset. For example, assume you work with the National Irrigation Board (NIB), you may wish to display all those farmers from Mwea Rice Irrigation Scheme who delivered rice in January to the National Irrigation Board. You can use a query object or statements to get the required records. The query statements are written using a special language called Structured Query Language (SQL). The user creates a, query by writing Structure query language statements such as: Select Farmer Number, Name, Month of Delivery From        Delivery Table Where Month of Delivery = “January”   Forms/screen input  A form is a graphical interface that resembles the ordinary paper forms used to collect data. However, a database form enables the user to view and enter data into a table. Figure 3.4 shows a sample form used for entering a student’s marks scored in four subjects and. the date of admission. Form interface is a more convenient and easy way of entering and viewing records from a table.   Reports  Most database systems provide the user with a tool for

2.1 Definition of a spreadsheet A spreadsheet is essentially a ledger sheet that lets you enter, edit and manipulate numeric data. There are two types of spreadsheets namely: The manual spreadsheet. The electronic spreadsheet. A manual spreadsheet is the most commonly used type by book keepers as a ledger book with many sheets of papers divided into rows and columns on which various amounts of money are entered manually using a pen or pencil. You can visit your bursar’s office and request to see a ledger sheet. An electronic spreadsheet on the other hand is prepared using a computer program that enables the user to enter values in rows and columns similar to the ones of the manual spreadsheet and to manipulate them mathematically using formulae.                                                        ‘ In this book, the word spreadsheet shall be used to refer to the electronic spreadsheet. ‘. Advantages of Using Electronic Spreadsheets over Manual Spreadsheet The electronic spreadsheet utilizes the powerful aspects of the computer like speed, accuracy and efficiency to enable the user quickly accomplish tasks. The electronic spreadsheet offers a larger virtual sheet for data entry and manipulation. For example the largest paper ledger you can get is one that does not exceed 30 columns and 51 rows while with an electronic spreadsheet, the least ledger has at least 255 columns and 255 rows! The electronic spreadsheet utilizes the large storage space on computer storage devices to save and retrieve documents. The electronic spreadsheet enables the user to produce neat work because the traditional paper, pencil, rubber and calculator are put aside. All the work is edited on the screen and a final clean copy is printed. With a handwritten spreadsheet, neatness and legibility depends on the writer’s hand writing skills. Electronic spreadsheets have better document formatting capabilities. 6. Electronic spreadsheets have inbuilt formulae called functions that enable the user to quickly manipulate mathematical data. An electronic spreadsheet automatically adjusts the result of a formula if the values in worksheet are changed. This is called the automatic recalculation feature. For a manual sheet, changing one value means rubbing the result and writing the correct one again.   Examples of spreadsheets VisiCalc: This was the first type of spreadsheet to be developed for personal computers. Lotus 1-2-3: This is integrated software with spreadsheet module graphs and database. 3. Microsoft Excel VP-Planner etc. In this book, the spreadsheet that will be considered in details is Microsoft Excel. Components of a spreadsheet A spreadsheet has three components  ­ Worksheet. Database. Graphs. Worksheet This is the component in which data values are entered. It is made up of rows and columns. The intersection between a row and a column is called a cell. A row is a horizontal arrangement of cells while a column is a vertical arrangement of cells. Each row is labeled with a number while each column is labeled with a letter as shown in the Figure 2.1. Each cell is referenced using the column label followed by the row label e.g. cell B3 has the value 20. A group of many worksheets make up a workbook. Database Data values can be entered in the cells of the spreadsheet and managed by special Excel features found on the Data menu. These features were incorporated in Excel but they actually belong to database management software. One of such feature is filtering records, using forms, calculating subtotals, data validation pivot tables and pivot chart reports. If the data values for the same entity (related values) are entered on the same row, they form a record. Hence a worksheet can be manipulated to some extent as a database that has data records entered in it. Figure 2.2 shows a worksheet having two records, Joy and Jeff. NB: A spreadsheet file is structured in such a way that it can be visualised as a table of records. That is why such a ‘file can be imported into a database program as will be discusses later in databases.   Graphs A graph is a pictorial representation of the base data on a worksheet. Most spreadsheets refer to graphs as charts. A chart enables the user to present complex data elements from a worksheet in a simple easy to understand format. Examples of charts are pie charts, line charts and bar charts. As shall be discussed later, it is easy to generate charts when working with a spreadsheet program. Figure 2.3 shows an example of a pie chart.   2.3 Application areas of a spreadsheet  Statistical analysis Spreadsheets provide a set of data analysis tools that can be used to save steps when developing complex statistical or engineering analyses. The user is usually expected to provide the appropriate data and parameters for each analysis. The statistical tool then uses appropriate automated statistical or engineering functions and then displays results in an output table. Some of the tools generate charts in addition to the output tables. Because most of these tools are complex, the user needs to have the statistical background knowledge before attempting to use the tools. Examples of some simple statistical functions include the following: Average: This is used to calculate the mean of a set of values. Median: This is used to return the value in the middle of a set of values. For example a set of values may be composed of: 10   20    30   40    50     60. The average of the set is 35 and its median is also 35. The median is found by taking the average of the two numbers at the centre of the set, in this case 30 and 40. Accounting Many accountants find the spreadsheet a useful tool to use in recording daily transactions and keeping of financial records. Spreadsheets provide a user friendly environment for financial management and they come with inbuilt functions that make accounting tasks easier. For example, the spreadsheet can be used by accountants to do the following: To track the value of assets over time (depreciation and appreciation) To calculate profits To prepare budgets

What is a word processor? A word processor is an application software that enables a person to create, save, edit, format and print text documents. Word processing is the act of using a word processor. Examples of word processors Examples of word processors include, Microsoft Word, Corel WordPerfect, WordStar, Lotus WordPro and many others. A word processor has a number of advantages over he type writer that include: A document can be stored in the computer for future reference in computer files that do not occupy physical space like the one on paper. This creates a paperless document-processing environment. Typing using a word processor is easier and more efficient because some actions are automated. For example, word-wrap feature automatically takes the cursor to the beginning of the next line once you reach the end of the current. Another automatic features common in most word processors is automatic insertion of a new page after reaching the end of the current page.  Most word processors have special editing tools such as spelling     and grammar checkers and thesaurus that help the user to easily Correct grammar and spelling mistakes. A thesaurus helps to find a word or phrase with similar meanings.  With insert and type over modes available in most word processors, one can easily insert or replace a word or a phrase without affecting the structure and neatness of the document. Word processors have superior document formatting features. Formatting refers to the art of making the document more attractive and appealing to the eye. Such features include, underlining, boldfacing, italicization, applying different colors etc.  While a typewriter may require that we retype the entire document when we want many copies, with a word processor, printing lets you produce as many copies per session as needed. Using the cut, copy and paste commands, you can incorporate other text without having to retype it.   Basic word processing features and concepts They allow the user to create a file, save it and open it again and again for reuse, editing or formatting. They have almost similar document windows with the following Features: Most are designed to look like a piece of paper with a few Most of the screen is blank before typing of text. There is a cursor, which blinks at the position where you can Begin entering text. There is a status bar or line that provides the user with current status information such as saving operation, the name of the file in use, the current page, the current imaginary horizontal-line and column cursor position. Word wrap: The feature that automatically moves a word or cursor to the beginning of the next line if it does not fit at the end of the current line. Scrolling: This is the vertical movement of text document on the screen. We can scroll through a text document using the up or do n arrow keys, page up and page down keys and also using, a mouse in windows based word processors. Help: Sometimes we get lost, confused or need more information on how to use an application. Help contains instruction, tips, pointers, explanations and guidance. You can get help by either pressing F 1 on the keyboard or clicking Help from the menu. Editing Modes: Word processors have two editing modes, insert and type over mode. In insert mode, every character typed between words, lines or characters is placed at the cursor position. This pushes all the text in front of the cursor away without deleting it. However in type over mode every character typed deletes what was there before and replaces it with new text at the cursor position. Nearly all word processors have a spelling checker, thesaurus (Dictionary of synonyms) and grammar checker. They provide for the use of headers and footers, indexing, footnotes and references, typefaces (fonts) and character set. Most word processors have ability to create and import tables, text and graphics from other programs. Mostly, word processors are used for writing letters, reports, projects, books, essays, memos curriculum vitae etc. Factors to consider when choosing a word processor The choice of a word processor depend on: The type of operating system. For example, most microcomputers are currently running on Windows based operating system such as Microsoft Windows. This means that you should consider acquiring a graphical user interface based Word Processor, Its user-friendliness, i.e. ease of use. Its formatting and editing features. They should be good and varied.   Using a word processing package Microsoft Word Microsoft Word is one of the components of Microsoft Office. Microsoft Office is integrated software with a number of interrelated programs. The programs include Microsoft Word, a spreadsheet called Microsoft Excel, and a database management system called Microsoft Access, communication software called Microsoft Outlook, and a presentation package called Microsoft PowerPoint among others. Although there are several versions of Microsoft Word, the most common are Word 97, Word 2000, WordXP and Word 2003. These versions of Microsoft Word are found in Microsoft Office 97, 2000, XP and 2003 suites respectively. Starting Microsoft Word There are a number of ways you can start Microsoft Word. However the Simplest is by using programs start menu. Starting Microsoft Word from the start menu Click the start button. Point to programs/ all programs if you are using Windows XP Click from the programs menu Microsoft Word screen layout Once you start Microsoft Word, it provides you with a blank document window referred to as the new document template where you can create your document. However you may need to use other specialised templates such as Faxes and letters, Memos and Web page. How? Click File then select New from the menu. The New dialog box in Figure 1.3 that appears enables a person to select a template by activating templates tab then double clicking its icon. With Windows multitasking capability, you can have more than one document window at the same time sharing one application window. However, each document window will have its own title bar

TOPIC 1 : WORD PROCESSORS – Click to view TOPIC 2 : SPREADSHEETS MS – EXCEL – Click to view TOPIC 3 : DATABASES – Click to view TOPIC 4 : DESKTOP PUBLISHING ( DTP ) – Click to view TOPIC 5 : INTERNET AND E – MAIL – Click to view TOPIC 6 : DATA SECURITY AND CONTROLS – Click to view

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