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This is a spreadsheet application term. We define an address as absolute so that the address will not be changed when the cell is moved or copied to a new location.
There are two types of cell address in a worksheet. These are relative addresses and absolute addresses. When we move a cell to a new location then formulas change as well as the location of the cell contents. For instance, suppose we have a formula =A3+A5 at location B7. When we move the formula to B11 it becomes =A7+A9. This is an example of relative addressing. In some instances we do not want to use relative addresses. We want to use absolute addresses. To make this happen in Excel we would enter the formula as =$A$3+$A$5. With absolute addressing we can be sure that the formula will not change no matter where we move or copy the cell.
This is a motor that can be switched off or on by an electrical signal. Actuators are used to control the movement of robot parts. They are commonly used in control systems where equipment is switched on or off depending on feedback from sensors.
An algorithm is a set of steps that describe how a problem can be solved. In computing there are many ways to create an algorithm. Flowcharts, Structured English and Decision tables are used by programmers to describe how a program is going to work.
Analog to digital converter (ADC)
Analog to digital converters are used where ever a peripheral generates analog input for a computer. The computer can only process data that is in digital form. The ADC converts from analog to digital. A temperature probe used for a science experiment might provide data that is to be displayed in graph form on a computer screen. The program that makes the graph processes a digital input signal to make the graph. The ADC converts the analog temperature data into the digital temperature data used for input by the computer.
The process of showing a number of pictures in sequence quickly to give the impression of movement. Cartoon characters are animated characters.
Software that is not part of an operating system is application software. Application software includes games, word processing packages, database software and graphics packages and so on. It is software used to make a computer useful for one specific purpose
Asynchronous Digital Subscriber Line
This is a communications technology that allows a telephone line between your house and the telephone substation to carry both digital (computer) data and also analog voice information. It means that a telephone line can be used to carry data and be used for a telephone conversation at the same time. The reason for being able to do this is that a telephone line has much more bandwidth than is necessary for voice communication. Surplus capacity is used for carrying computer transmissions.
Automated Data Capture
We capture data without having to input information manually.
v Barcode readers used in a supermarket capture data automatically.
v Control systems such as an air conditioning system controller, use a heat sensor and feedback loop as input to control the temperature in a room.
v We use OCR, MICR, OMR, voice recognition and biometric technologies for automated data capture.
This is often called secondary storage. It is non-volatile storage that is used to store information permanently. When the computer is shut down no information in the backing store is lost. Hard disks, floppy disks, CD-RWs, tapes and pen drives are used for backing storage. Access to backing store is much slower than access to main store data locations. The type of storage we use depends on whether we want random access to our data or serial access to our data. Tapes are used for serial access. These are high capacity and inexpensive - ideal for storing backups. Other types of storage such as hard disks, pen drives and floppy disks are more expensive but allow faster random access to our data.
This is a copy of an existing file. It is created to ensure that it will be possible to rebuild a system after data has been corrupted or lost. Many backups are made. A grandfather/father/son backup system is often used. This means that not only will there be a backup of yesterdays work but also the day before and the day before that. This is necessary because sometimes errors in files are not detected right away and it may be necessary to go back several backups to find a place before when data was corrupted.
A series of thin and thick lines that contain numeric data that can be read by a bar code reader. There are different types of bar code. International standards for barcodes include the ISBN, UPC and UCC standards. Different types of bar code store information in different ways.
v The Uniform Code Council barcode is used on products in shops and includes the following information (i) A beginning code number (101) that indicates where to start reading the barcode from (ii) a code for product type (iii) manufacturer identification number (iv) centre separation bars (spacing) (v) a five digit product identification number (vi) check digit (vii) and end code to indicate the end of the bar code.
Bar codes on products make it easier for a business to process transactions. There will be greater speed, less errors and a better service provided to customers.
This means delayed processing. Batch processing systems are used for systems that produce monthly bills for customers. These systems are suitable for applications where there is no requirement for instant processing.
Two advantages that batch processing systems have over real time systems are:
· It is not necessary to be online for processing all the time. This saves money because being online can be very expensive, especially if mainframes and networks are involved.
· Input for batch processing can be controlled nicely before it is processed. This can be difficult to do in a real time environment. Many applications are suitable for batch processing.
Batch processing systems are used for
v Producing pay-slips for employees at the end of the month.
v Processing bank cheques is another example of where it is appropriate to use batch processing. The bank can schedule cheque-clearing when there is little demand for computer time – such as late at night.
v A system for producing electricity bills uses a batch processing system. The information for processing (input) is collected on forms. The forms are all processed at the end of each month to produce electricity bills (output) for customers.
A place on a network where users can connect and leave messages. Other people with a similar interest can respond to the messages. Bulletin boards are places where people who have a common interest can share information.
A section of computer memory that is used to hold data temporarily while it is waiting to be sent a peripheral. Buffers are used because different devices operate at different levels of performance. A printer has slower data throughput than a system unit.
· When we print from an application the data to be printed is very quickly transferred from our application program’s data memory to a print buffer. The data is then slowly transferred from the buffer to the printer. There is a need for a buffer because an application package produces information far more quickly than a printer can cope with.
Capture data from form
People fill in a form. The form is carefully designed so that data can be encoded. Encoded information is used by data entry clerks to quickly and accurately input data for processing. In some cases the encoded information can be read directly, using OCR technology with no need for data entry clerks. Manual data entry, called “key to disk” is used to copy the information from the form into a file on the computer.
A check digit is a single digit placed at the end of numerical computer data. The last digit of a barcode is a check digit. Check digits are number placed at the used to verify that a bar code has been read correctly by a reader. Check digits are used to make sure that packets of information transmitted over a network have not changed. A check digit is generated by applying a formula to the numerical computer data that is to be read or transmitted. The computer data is sent to its destination along with the attached check digit. The receiving computer can apply the same formula to the received data and generate a check digit. If the check digit does not match the one sent from the source then the receiving computer will know that a transmission error has occurred. Usually this will mean that the packet of information is resent and another check is made to see if it has been read correctly this time.
A clipboard is a place for temporarily storing information that has been cut or copied from an application. Once stored, it can then be inserted back into the same application or else the clipboard data can be copied into a completely different application. Note that the term clipboard only applies to Microsoft software and not software produced by other companies.
Command line interface
A user interface for a computer. A command line interface lets users to enter commands with a simple line of text. For example, we could type in a command like c:\windows\system\ ping 192.168.1.200 –t to execute an operating system command that checks network connection speed. Command line interfaces are preferred by experienced computer users and system developers because they allow better control of a computer system and better performance than equivalent GUI systems. One disadvantage of a command line interface is that the user needs to be able to remember a list of key words and related parameters and be able to type them into the computer without making any mistakes.
A compiler is a computer program that translates source code into machine code and links it to libraries of existing machine code procedures and functions. The result of compiling is an executable file made up of machine code instructions. The executable file is often called object code. The object code is able to be processed by a computer. The source code is a list of instructions written in a high level language like Visual Basic. The source code must be compiled into machine code before a processor will be able to understand it.
A control interface is some electronics used for ensuring that the sensors in a control system can communicate with a computer. The function of the control interface is to change analog sensor signals into digital signals that can be used as input to computer program.
Cut and paste
Cutting means copying text to the clipboard and then deleting the same text from the document. Pasting means inserting a copy of clipboard information into a document at the cursor location. We cut and paste when we want to move information from one location in a document to a new location. For example we would use cut and paste to move a paragraph from the end of a page to the beginning of another page.
Data is the name given to input that is to be processed by a computer. The input source can be a keyboard, mouse, disk file, scanned image, digital camera picture, heat sensor signal, infrared signal, and barcode data and so on.
Data logging is a technique used to gather information that can be used for testing a computer model.
v We could construct a model of a road intersection and then verify the validity of the model by matching model output with the data acquired by data logging.
v We can log data to see what the rainfall is for a country.
v We can log data about pollution in a river.
A sensor is required to take measurements for data logging. Some means of storing the sensor information needs to be used. This might mean using a control interface that is connected to a small transmitter that can send signals to a computer where data is stored in a hard drive.
Database Management System (DBMS)
A software package that is used to manage a database.
v Most businesses that sell things operate a transaction processing system to record information about sales. The transaction processing system will interact with the business database to update sales information and stock levels for products.
The DBMS is the software that controls the way in which the database is accessed, updated and how data is processed.
Data capture means getting data (input) for processing by a computer. Input may be collected "automatically" or "manually".
v A bar code reader is used by a cashier at a supermarket to capture data about products automatically.
Related terms to know are encoding and decoding.
Data capture form
A form to be filled in by people and then used as a source document for data entry into a computer. The list of things to consider when designing a paper form that is to be used for data capture is very large. Some of the thing to consider include: (i) The type, colour and size of paper. An insurance form is going to have different requirements to an invoice form since an insurance form will have to last for many years. (ii) Is the form to be manifolded - are several carbon copies required. (iii) How many zones is the form to be divided into? (iv) Are the zone titles meaningful? (vi) Does the form include embedded instructions. (vii) Is the use of lines and boxes helpful for the user? (viii) Are captions properly designed?
Well designed forms will help to ensure that data is captured accurately and efficiently. Designing forms is a skill that requires good training. Well designed forms save an organization money by ensuring accuracy and minimizing the need to process incomplete or incorrect forms.
We use compression to reduce the size of a file. This is important to do if we want to save disk space or if we want to transmit a large file over a network. Many programs use compression automatically so that the amount of space a file takes up is minimized. The disadvantage of compressing files is that before a file can be read it must be decompressed. The decompression process may take some time to complete – time which is added to the speed of processing for an application. Graphic files such as digital pictures are often compressed using the jpeg format. Files sent over the internet are usually compressed first so they can be transmitted quickly with the least cost.
Refers to the validity of data. Data integrity can be compromised in a number of ways:
(i) Human errors when data is entered
(ii) Errors that occur when data is transmitted from one computer to another
(iii) Software bugs or viruses (iv) Hardware malfunctions, such as disk crashes Natural disasters, such as fires and floods.
There are many ways to minimize these threats to data integrity. These include: (i) Backing up data regularly (ii) Controlling access to data via security mechanisms (iii) Designing user interfaces that prevent the input of invalid data (iv) Using error detection and correction software when transmitting data
This means doing everything possible to ensure that an information system remains secure. This means protecting information from criminals, equipment malfunction and natural disasters or fire. Security threats include unauthorized access to data and damage to files by malicious programs such as some viruses.
v A disaster recovery plan is used as a way of recovering data quickly from backups in the event of system failure.
v Preventative maintenance ensures that the chance of equipment failing is minimized.
v Physical security such as biometrics, locked doors and computer passwords.
v Software protection against threats includes the use of antivirus protection, firewalls and a good network security by preventing unauthorized access to certain parts of a network where sensitive information is held.
Decoding means changing information in encoded form into a form that is easily understood by people.
v The encoded information NABILAH02ENG98PMB can be decoded to read "Nabilah sat PMB in 2002 and she achieved a mark of 98 in her English examination."
Desktop publishing Program (DTP)
Application software for creating commercial standard publications such as magazines, invitations, advertisements and books. A DTP has much better control over text and graphics than we might expect to find in a word processing package. DTPs are designed for assembling very large pieces of work such as a novel or for very detailed work such as a wedding invitation.
Digital to analog converter (DAC)
The output peripheral attached to a computer may only accept an analog signal. For instance, when we connect to the internet we transmit information over the telephone line. The telephone line (old ones anyway) carry an analog signal and not digital. We must convert our digital signal to analog (with the DAC in our modem) so that transmission to our service provider can take place.
An electronic device used to convert hardcopy diagrams into digital form. A stylus can be moved over a paper diagram and movements of the stylus are reflected on the screen of an attached computer.
v A digitizer can be useful to a person using a CAD program. The CAD operator can trace over a map with the digitizer and the map would then appear on the screen.
Dot matrix printer
Impact printers are commonly found in the business world.
v Most businesses will use a dot matrix printer to produce receipts for customers.
v These printers are reliable, fast and cheap to run. Businesses sometimes have to manifold documents (produce carbon copies).
v Dot matrix printers can do this whereas inkjet and laser printers can not be used for these purposes.
v Dot matrix printers tend to produce low quality output because they have lower print resolution than other types of printer.
This means standardizing input so that there will be less errors. For instance, we might make sure that dates are put into the form DD-MM-YYYY. This would make sure that there are less input errors created by people who use their own style of date. Sometimes we encode information so that it can be stored efficiently. For instance we might encode some data in the form NABILAH02ENG98PMB. This information could be decoded to say "Nabilah sat PMB in 2002 and she achieved a mark of 98 for her English."
Data encryption is a technique used to make it impossible for unauthorized access to information that you have on a computer. Even if people can open a file that has been encrypted they still can not understand it. We often encrypt information before sending it over a network to another computer. It is common practice to encrypt credit card information before it is sent over the network to a company you are making a purchase from. This is so that criminals can not get your credit card details and then start buying things that you have to pay for.
Storage, such as floppy disks, pen drives and removable hard disks that can be removed from the computer system
Expert systems are a part of a general area of computer science called artificial intelligence. An expert system is a model of a human in the sense that the computer is programmed to "think". The computer is able to make decisions based on its "experience" and the decisions it has made in the past. The model is very good for managing financial situations such as when to buy and sell shares on the stock market. The knowledge stored in an expert system is called the knowledgebase. The part of the system that does reasoning is called the inference engine.
Export means to transfer information created with one package into another package. This often means translating the source information into a format that is acceptable to the destination package. For instance, a flowchart made with VISIO can be imported into a word processing file as long as it has been saved in an acceptable format such as jpeg or bmp. A worksheet table of information can be exported to a database table. A database table can be imported into an Excel worksheet. In many cases, the conversion of data types is not seen by the user.
A network that belongs to a business and is for the business, but it does allow access to some parts of the network by people such as customers. A web page might advertise products – obviously it would be a good idea if customers could access this to find out about items they might like to purchase.
This is a report produced at an early stage of a system development life cycle. It is the product of a feasibility study. It is an important report that is prepared for the sponsors of a proposed project. The sponsors must use this report as the basis for making a decision about whether to go ahead with development of a system or not. In the feasibility report the system analyst will hopefully be able to identify the chance of creating a system successfully and will be able to roughly estimate the costs and benefits of any proposed system. The report will provide a rough estimate of how the project will be managed – how long it will take and what resources will be required. The report will define the scope of a proposed system. It will define an automation boundary that says what parts of the system will be computerized and which parts will remain manual. It will attempt to justify the conclusion reached by the system analyst. In real life initial estimates of time, resources and cost are rough estimates only. Fortunately, costs and benefits are refined and reviewed many times as the project gets further developed.
This is a status signal that is supplied by computer controlled equipment in a control system. The status signal is used as input for further processing by a controlling computer.
v An automatic door opener for a supermarket. A feedback signal from the motor that is opening the automatic door at a supermarket is sent back to the door controller (computer). The status of the door, whether it is open or closed, is used as input for a program that controls the door motor. Clearly, if the motor is already opening the door then there would be no need for the computer to send a signal to get the motor to start opening the door. When the door is fully open the computer might eventually send a new signal to the motor to get it to shut the door. It will only send the signal if the door is already open and is not in the process of shutting already.
There are a couple of different explanations for field. (i) A column in a database table. A database table is made up of records and fields. The rows are called records and represent information about one person or thing. The columns are called fields. A single record may contain information about one person such as their name, age, gender, home address and phone number. In this example gender is the name of a field for the database. (ii) A record is divided into parts called fields. A field contains information about one thing in a record. For example the name field contains information about a person’s name.
Database tables contain rows called records and columns called fields. The type of information allowed in a field is called the field type. Valid field types include (i) Boolean, (ii) long integer, (iii) character, (iv) integer, (v) currency. There are many more field types that can be used.
Fixed length field
Some database tables are made up of fixed length fields. When this is the case the size of a field is preset when the database table is defined. For example we might set the field length of a field called Name to 150 bytes. If we add the name like “Nazree” then we will add 150 bytes to the size of the database since all names will be fixed at 150 bytes no matter how big the name is. In this example we could argue that 144 bytes of storage will be wasted since “Nazree” is only 6 bytes long. Because all records are the same size it is easy to work out where in a database a record or field will be. For example, if we need the 10th record in a database where records are all 47 bytes long then we just need to move to byte number 470 in the file and then start reading the 10th record. Fixed length databases are less complicated to manage than variable length databases. Modern database systems usually use variable field length design for table definitions.
Floppy disks are used for storing digital data. A Floppy disk is a single thin low capacity plastic disk that needs to be inserted into a floppy disk drive before it can be accessed. A floppy disk is useful for ‘small’ amounts of data. 3 ˝ inch floppy disks can hold 1.44 Mb of data.
This is a type of text such as times new roman or Arial. Font and typeface are words that have the same meaning.
v We can change the font style (italics, bold, underscore, strikethrough… )
v We can change the font size (8, 10, 11, 12,
A spreadsheet term that refers to an expression that is automatically calculated by the software.
v =A3+B5 is a formula. The application software will calculate and display the value of the whatever is in cell A3 when it is added to the contents of what is in cell B5,
A spreadsheet term that refers to built-in spreadsheet functionality. For example we can use the SUM function to add up all the values in a range of cells.
v = SUM(B3:D13) will add up all the values in the range of cells between B3 and D13.
Grandfather-Father-Son recovery plan
A method for protecting data by making backups of an important file. The son is the current file that is on use in the organization. The father is a copy of the son file that is kept in a safe place, perhaps on disk in a safe. The Grandfather is a copy of the Father file and this is stored off-site in a safe place.
v In a small retail business the son file is the database file for a transaction processing system that is used to record sales.
v At the start of the day a new Grandfather file is created by copying the father file. The business man will take home the Grandfather file and store it safely. After making a new grandfather file the father file will be created by copying the son file. The father file is kept in a safe place at work.
By following this procedure the businessman can be sure that if his work database is corrupted or destroyed then he can use the father file or grandfather file to restore his data. The data in the back up files will be a little bit out of date, but at least the businessman will not have to remake the entire data file if it has been damaged.
A graphics tablet is a pressure sensitive layer under an LCD screen that is used for digitizing user input. A user can use the tablet to "hand write" information and this will then be digitized and converted into text inside the computer. Powerful OCR software can be trained to "read" hand writing (no matter how bad) as long as the writer is consistent.
Graphical User Interface (GUI)
A computer user interface that makes use of graphics instead of text. In a Microsoft Windows GUI small pictures called Icons are used to trigger execution of applications (when clicked).
v Equipment such as photocopiers, digital cameras and other electronic equipment have graphical user interfaces.
Hard disks are used for storing digital data. A hard disk is made up of three or more disks with individual read write heads for each surface. Hard disks often have integrated controllers built into to speed up access to the information on the disk. Any computer application that requires immediate access and large amounts of storage is likely to use a hard disk drive for storage and application software. Most of the software used on a PC is permanently stored on am internal hard disk because floppy disks do not have enough storage for modern application software programs.
The first page to open at a website. Each html page has a name. The default name for a website home page is index.htm
v When we go to the website http://www.brunei-bay.com then the file at location http://www.brunei-bay.com/index.htm will be loaded into the browser of our computer for us to view.
Immediate access is the same as random access. It is necessary when a computer processor must response to input without delay. It would be sensible to have random access storage of account information when a PIN number for a bank card is to be verified while a customer is using an ATM machine. It would be silly to have the customer wait for several hours for their PIN to be verified because all the account information is stored on a high capacity serial access tape. We do not need random access to backups and we do not need random access to very small databases (such as shopping lists). In both these cases serial access is a more sensible choice.
To move a block of text in from either the left or right margins.
An inkjet printer will produce nice colour printing by spraying small amounts of ink onto a page as the page is fed underneath a print head.
v The quality of output is good, even up to photo quality standard. Special paper can be used to produce excellent photographic prints.
v The high quality comes at a high price. Printer refill cartridges are very expensive and do not last very long. High quality photo printing paper is also very expensive.
v Inkjet printers are slow when compared to other types of printer.
v They can be unreliable when ink nozzles get blocked with dry ink, causing low quality output to be produced.
An input device is hardware that provides data for processing by a computer. A barcode reader, keyboard, scanner and microphone are all input devices. We use automated data capture because : (i) reduces time required to handle input (ii) increases the accuracy of input (iii) increases the productivity of workers by taking away tasks that are more easily and effectively carried out by machines (iv) increases the profit of a business using such technology (v) enables a business to offer new services (differentiate) hence helping a business to gain more customers than competitors.
This is a feature of a word processing package that allows the user to insert text in the middle of an existing block of text. In insert mode text entered to the right of the cursor is moved a space further to the right before any new key press result is entered at the cursor position. See overtype mode.
An integrated package will consist of several separate packages that are able to easily share data between themselves. Each package will also have the same style – similar menu structures and common button styles. Microsoft Office is an integrated package that contains many office automation tools such as a word processor, spreadsheet, DBMS and presentation package
An interactive system will allow a dialog between the computer and the user.
v An ATM system is an interactive system. The system will respond to the user’s input. The user and the computer have a dialog. When the user enters input then the computer will respond with a screen message. Interactive systems are also event driven systems since the computer only responds after the user provides input.
v Microsoft Windows is an interactive environment. The computer responds to user interaction.
The internet is a Wide Area Network that allows many computers to communicate with each other over large distances. The World Wide Web is the network of computers that use the internet but transmit pages to each other that have been prepared using HTML. (hypertext markup language). We use a software package called a browser to view web pages.
An interpreter will execute a source code program by translating one instruction at a time into machine code and then sending the machine code to the processor for immediate execution. Interpreters are often used for developing software as they work quickly and are good for debugging. Final versions of software are nearly always compiled into machine code using a compiler. Interpreters are good for development and compilers are used to produce final versions of software.
A computer network that is limited to a single organization. It could be a LAN but is more likely to be a number of LANs that are linked together by a WAN.
v Brunei Shell has an Intranet for internal communication. Brunei Shell Customers can not access this network. The network is only for Shell employees.
A job is work to be done in a batch processing environment. Many jobs are lined up in a job queue. The job queue is controlled by a program written in a JCL (job control language). Jobs, job queues, and JCL are terms normally associated with mainframe computers.
Work to be done in a batch processing environment is placed in a job queue. The jobs at the front of the queue are processed first. New jobs can be added to the end of the queue. The jobs are controlled by a program written in a JCL (job control language).
A unit used for storage of data in computer systems. 1 kilobyte = 210 bytes. 1 Kb= 1024 bytes. Note that 1 Mb = 220 bytes and 1 Gb = 230 bytes.
A high quality printer that is suitable for office work. It is quiet, fast, reliable and inexpensive to run when compared with an inkjet printer. Some laser printers can print in colour, however these printers are very expensive and it is unusual for a small business to own one.
Liquid Crystal Display.
This is a technology used for computer screens. It is commonly used for the screens of portable computers and calculators. It is a common feature of the user interface of many electronic products such as digital cameras, ovens, microwaves, washing machines, air conditioning units and so on. LCD screens are lighter, flatter, use less power and take less space than CRT screens. People who require very high resolution and a fast refresh rate may prefer a CRT screen for their work as the resolution and performance might be better than that provided by an LCD screen. The cost of an LCD computer screen is still much higher than the same size CRT screen - which explains why people still use CRT screens!
Local Area Network (LAN)
A LAN allows communication between computers. LANs connect computers in a small geographical area. Generally, network cables between computers are limited to a maximum length of around 100m, depending on the type of cable. The distance between computers using a wireless LAN is much less than this. LANs are generally fast, with much greater bandwidth than most WANs – which must use a relatively slow public telephone system.
A macro is a set of instructions that make the computer carry out some task. For instance we can create a macro in Microsoft Word that will change the printer orientation to landscape simply by pressing a control sequence instead of going through a number of screens to do the same thing. Macros save time. They are also dangerous. Viruses are often written in a macro language and can cause a lot of trouble when you attempt to open a file that contains a macro virus.
A strip of magnetized media on the back of a credit card or debit card. It is used for identification purposes and can be read by such devices as the card reader in an ATM machine. The magnetic strip contains a very small amount of information about the card holder. It is a security feature of a credit card.
Magnetic tape is used for secondary storage. It is often used for making backups. This is because high capacity tape is much cheaper per megabyte than hard disk space. As long as serial access to data is satisfactory then tape is a good storage choice.
This is a word processing feature. We can combine a file of data with a standard letter to produce a large number of individual letters. For instance, we might use mail merge to send out individual letters to all members of a club. We would need to create a list of member’s names and addresses in one file and the standard letter in another file. When the mail merge process is carried out one letter will be printed for each member. Each letter will contain the individual members own name and address information and it will look like the letter was written especially for him.
This is the memory inside the CPU that is accessed directly. It is usually made up of RAM chips and contains instructions and data for application processing. Sometimes this memory is called primary storage. This memory is volatile – meaning that its contents are lost when the computer loses power.
Computers used for large scale data processing by big organizations such as government departments. Database applications are often "resource hungry" making them unsuitable for implementation on platforms less powerful than that provided by a mainframe. They are often used in Universities for scientific and financial modeling. Many computer models are very complex and require the processing power of a mainframe to operate successfully.
v Economic models are used to predict future economic trends that governments can use to help make decisions about the economy and monetary policy.
v Weather models are very complex and require the use of a mainframe computer to make predictions.
Some Mainframes are called Super Computers. Research "Cray Computers" on the internet to see how powerful the most powerful mainframe computers are.
Magnetic Ink Character Recognition (MICR).
The use of magnetic ink to store data that is to be input into a computer system.
v Bank cheques are encoded with magnetic ink characters. Magnetic ink is used because it is (i) machine readable and (ii) because it is hard to forge.
Computers that have a single chip processor are called microcomputers. Laptops, PDA’s, Notebooks and PCs are all microcomputers.
A single integrated circuit that processes data and instructions inside a computer. A microchip can have over 1,000,000 electronic components placed on a semi-conductor circuit board. It is very small and yet can carry out many thousands of instructions every second.
A computer model is a simulation of a real situation. They are used for prediction and for training.
v Computer models are used to simulate the weather. The model is then used to predict the weather in the future.
v Financial models are used in business. These models let business people see in advance what the effect of making business decisions will be. For instance, a financial model might tell a business how monthly profits will change if the business spends $1000 on an advertising campaign on the radio.
v Whole countries use economic models to try and predict future trends for metrics such as the unemployment rate, gross domestic product and the rate of inflation. The model is used by economists to help them to understand the effects of making decisions like "raising interest rates".
v A road model can be used to experiment with the timing of traffic lights at an intersection. The timing can be worked out so that disruption to motorists is minimized.
v Pilots use simulators to practice procedures for handling emergencies without the need to practice procedures like "crash landings" using a real airplane.
Models let us experiment with model parameters. They help us to understand a problem better. They help us to predict the future. The cost of changing model parameters is small when compared with the cost of changing the real environment. The validity of a model depends entirely upon how well the model represents reality. So, it is very important to understand the reality very well. To help to understand this it is common to (i) collect data from the environment to be modeled. (ii) Create a prototype model. (iii) Test and improve the model using the environment data collected earlier (iv)The model becomes a useful tool for prediction.
Morphing is a graphical technique that involves changing the view of one object into that of another object. We can morph a cow into a chicken using special graphics software package.
A system is multi access if the processor is online to more than one user at the same time. An airline booking system is one example of a multi access system. Many ticket booking terminals access a central computer to make airline bookings at the same time from different places. Mini computers and mainframes are multi-access. Multi access systems are usually real time systems and also multi user. An EPOS system for a supermarket is multi-access. Many cashiers can access the same central database at the same time. The cashiers input information about products using a barcode scanner. The product information is sent over a network to a centralized database where two processing things happen. (i) Information such as the product description and cost are returned to the POST so that a receipt can be produced and information can be displayed on the LCD. (ii) Information about stock levels is updated on the database. The database is used to decide when products should be ordered to maintain sufficiently high stock levels.
The computer can be running more than one application at the same time. The computer will divide up its available memory into different parts for different applications. Windows is a multi programming environment. We can run a spreadsheet application, web browser and word processor all at the same time (as long as there is enough memory). Mainframes are multiprogramming since not all users will be using the same application at the same time.
A multitasking computer is able to do many different jobs at the same time. This is an operating system feature. For example, in a multitasking environment the computer might be able to print your document, update the screen with messages and load a file from a disk all at the same time.
Optical Character Recognition (OCR)
An image is scanned and then OCR software is used to correctly recognize the formatted mixture of text and graphics.
v For instance, we can scan a page from a book and then use OCR to convert the scanned page into a word processing document that we can edit. Omni page is a software package used for this purpose.
A device is online if it is under the control of the CPU of a computer. If a peripheral such as a printer is offline then the CPU is unable to send or receive data from it. We can make a printer offline by switching it off or disconnecting the data cable.
A program that is used to control the hardware of a computer system. An operating system has some or all of the following utility features
Optical Mark Recognition (OMR).
This technology is used to read marks on preprinted forms.
v It is used for reading multiple choice questions for examinations and for election results.
v It can be used for any situation where all that is required is that boxes are ticked rather than a user having to write text.
This is a keyboard entry feature of word processing software. In overtype mode text that is being entered from the keyboard replaces text located to the right of the cursor. Also see insert mode .
Data to be transmitted is put into a special sequence of bytes called a packet. Packets are a fixed size depending upon the protocol being used. A single message from one computer to another may consist of many packets. Additional information including a check digit, sender IP address and destination address is added to the user data that is to be sent. If the check digit arithmetic shows that the packet received is corrupted then the receiving computer will send a request to the source computer asking it to resend the same packet again.
This is a strategy for implementing a new system. The new system is run along side the old system. The existing system is used as a control to verify that the new system is working correctly. This is an expensive option for implementation as it means running two systems at the same time which involves a lot more work for employees.
An electronic device that sends or receives data from a CPU. Peripherals may be internal or internal. Examples of peripherals include printers, monitors, disk drives, scanners and so on.
A way of changing over from an old information system to a new system. The new system is tried out in a small area of an organization or business. If the system works as predicted then it is implemented across the whole organization.
· A business might put EPOS terminals into one branch of a department store chain. If the system works as predicted after being tried for a few months then EPOS terminals can be introduced to all the other branches.
There are two types of plotter (i) flatbed plotters (ii) drum plotters. The plotter does use actual pens and creates lines by moving the pens over the page in the same way that we would create a drawing manually. This is different to the technology used by printers where pictures are made by joining dots together. A flatbed plotter will draw diagrams with pens on a piece of paper that is fixed on a flat tablet. A drum plotter can print on very large pieces of paper. It does this by moving the page back and forwards over a drum.
Point Of Sale Terminal. This type of terminal is used in supermarkets and shops. The terminal is connected to a central computer that has information about the products being sold. See also EPOS terminal.
A primary key is a single column or else a combination of columns that is used to uniquely identify rows in a table of a relational database. Each row in the table can be identified uniquely by its key. A single table will have one or more candidate keys. Candidate keys are keys that COULD be used as the primary key for a table. Only one of the candidate keys is chosen to be the primary key. A related term is foreign key. A foreign key is a key in a table that is the same as the primary key in another table. Foreign keys are used to define relationships between tables in relational databases.
Commonly, this means that a computer (with sensors) is used to control an industrial process without the need for human intervention. There are many advantages for doing this: - the computer system can respond very quickly to changing conditions since sensors provide information many times per second. Quality of product will be higher than for an equivalent manual processing system.
A processor is the part of a computer system that carries out processing. In a microcomputer the processor is a single chip such as an Intel Pentium IV. In mini computers and mainframes the CPU will be made up of many processors all working at the same time. The processor contains a control unit and arithmetic logic unit. It also contains registers.
A program is a set of instructions for a computer. Programs are stored in files on secondary storage such as a hard disk. When we start a program the operating system will copy the program into the RAM of our computer and then send instructions from RAM to the CPU where processing will take place. Most modern applications are made up of many program files. An application may consist of many different programs. Along with program files there might be data files that contain information needed by an application or created by an application. Data files do not contain program instructions. A digital picture stored on a disk is an example of a data file.
This is managing the resources needed to ensure that a project is finished on time and within budget and to the satisfaction of the end user. Project managers use tools such as PERT and Gantt charts for scheduling all the tasks that need to be completed. They are conscious of managing time, scope and resources for a project. To reduce time to complete a project the manager might decide to employ more workers which would increase costs. Or it might be that the scope of a project is changed so that it takes less time to complete the project. The project manager is always making decisions that balance the conflicting forces of time constraints, project scope and costs.
This is a way of accessing computer data. In a random access environment any part of a random access file can be accessed with little or no delay. Random access means fast access to data. Hard disks and floppy disks are used for random access.
An error that occurs when media such as a floppy disk is being read and an error is found. Read errors indicate that either information was not saved properly in the first place or else the storage media has been corrupted at some time later.
Real time Processing
This means there is little or no delay in processing. The ATM machine is a real time system. These systems are often single purpose and involve use of a dedicated computer. An airline booking system is online. The controller for your automatic washing machine is a real time computer system. An ATM system is a real-time system. When the user enters a PIN number at the ATM the computer system responds without delay. A control system for air-conditioning is also a real-time system. Sensors provide information about the temperature. This information is then processed by the CPU without delay.
A row in a database table. A record is a set of related information about one thing or person. For example a single record may contain information about a person such as their name, age, gender, home address and phone number.
This is a spreadsheet term. It refers to the way a formula will change when a cell is moved or copied from one location to another.
v A formula =A3+A5 at location B7 will change to =A7+A9 when B7 is copied to B11. This is an example of relative addressing. When the cell at B7 is copied to a location 4 cells lower in the same column then all the formula addresses are also changed to positions 4 cells lower.
This is the first step taken by a system analyst when developing a new information system. It is sometimes called the problem recognition phase. The system analyst needs to create a paper model of the system as it currently exists. He needs this so that he can understand what the system is supposed to do. His model will show that he understands the system and this can be verified by walking through his models diagrams with users. His model consists of information collected from user interviews, data flow diagrams, a data dictionary and entity relationship diagrams, process specifications, system flowcharts and any other text or analysis diagrams that he thinks helps to clearly show how a system functions. Note that although we have considered creating a model of the existing system as the first step for developing a system it is not always necessary or indeed wise to do so. Some system development life cycles do not include analysis of the existing system.
Resolution refers to the quality of a screen display or the quality of printed output. High resolution screens are needed for graphics applications such as those used for CAD or desktop publishing. Screen resolution is measured in pixels. The smaller the pixel size the higher the resolution. We can increase the resolution of a screen by increasing the number of pixels displayed on it. For instance, a screen resolution of 1024 x 820 pixels is much better than a screen resolution of 800 x 600 pixels. Printer resolution is measured in dpi (dots per inch). If there are a lot of dots per inch then the resolution is good. A dot matrix printer might only have a resolution of 80 dpi (use for receipts in a shop). A laser printer might have a resolution of 300 dpi (good for business letters). Magazine quality resolution is 800 dpi. Photos can be 80 dpi if they are shown on the screen. If photos are to be printed then they should have resolution greater than 300 dpi.
A scanner is used to transfer an image into digital form on a computer. There are two types of scanner (i) handheld scanners (ii) flatbed scanners
v A hand held scanner captures an image as the user passes the scanner over the surface of the source material. These small portable scanners, with the addition of wireless communications, become very useful for doing things like scanning product codes in a large warehouse.
v Flatbed scanners are larger than hand held scanners. They have a glass plate upon which we place the document to be scanned. The scanned image is generally of a very high quality when a flatbed scanner is used. This is not the case with a hand held scanner.
A sensor is an electronic device that provides a signal indicating the value of some environmental variable. Sensors can measure temperature, light, moisture, movement, noise level and so on. Sensors connect a computer to the outside world. They provide important input for programs that control equipment. The sensor that indicates temperature is used as input by the computer that controls the air conditioning system in our classroom.
We have serial access data on a tape. To read information at some place in the middle of the tape we must go through step by step through all proceeding parts of the tape first. Tapes have high capacity and are cheap. Alternatively, hard disks can also store a lot of data but they are much more expensive to buy than tapes.
A computer model used to simulate reality. These models are used as the basis for decisions.
v A model for managing the macro economics of a country is a simulation model. This model is used to see the effect of making financial decisions. Governments need to make good decisions so that people can get wealthy and the number of people who are unemployed is reduced.
Single user system
This is a system that can process input for only one user. Ordinary PC’s are usually single user. This is because the resources of a PC are not sufficient to provide suitable performance for many users at the same time. Mini computers and mainframes are multi-user systems
Speech recognition is the ability of a computer system to respond accurately to verbal commands. There is an increasing number of applications for this type of technology.
v Controlling household appliances
v Turning down the music in your car without the need to remove hands from the steering wheel.
v Some hand phones are voice activated.
v In industry voice recognition is useful when an operator is busy using their hands for something else. A dentist might control equipment with verbal commands rather than have to put sterile fingers on a dirty keyboard and then back in the mouth of the poor patient!
A spreadsheet is a computer package that is used to automate the activities of a person using a pencil and calculator. A common use of a spreadsheet package is to automate a financial model. A business person can explore a financial model of the business to predict the effect of decisions he might make. For instance, the spreadsheet can be used to predict the result of investing in an advertising campaign.
A standard letter is a template of a letter that can be used with only small alteration for many different situations. A standard letter for overdue library books might be used by a library many times per week. Rather than retype the letter over and over again, the standard letter is loaded and a few details such as the member name and the names of overdue books are added before the letter is printed. Standard letters are sometimes combined with a data file and mail merged.
A stepper motor is a computer controlled motor that can do a small amount of work when it receives a signal to do so – then it stops. We might use a stepper motor to control an automatic door. We would need to keep sending the stepper motor signals until the door was fully open. Each signal would make the door open a small amount. Of course, many signals are sent in 1 second, so we get the impression that the door opens automatically.
Structured Query Language
Structured Query Language. This is the industry standard language that is used by application software to access a database. There are several variations of SQL, however, there is a common instruction set that can be relied upon to work with nearly all databases. SQL lets us create software that is independent of the underlying database technology platform. It makes our software scalable – we can change the underlying database in the future without having to change our software too much. All we would need to change from say Access to Oracle is to find the correct driver that will change our SQL commands into commands that can be handled by the Oracle database engine.
System Development Life Cycle
This is a sequence of steps to be taken to create and maintain an information system. There might be 8 steps or there might be 58 steps. It depends on what level of understanding of systems analysis we have and how big or complex the information system is likely to be.
v If we were to build a database for a school library system our SDLC might include the following sequence of steps. (i) Identify what the database is required for. This means identifying the objectives of any proposed system. (ii) Identify the outputs that will be produced by the system. These might be screens, results of queries and reports. (iii) Identify the user functions that the database is going to be supporting. Is the database likely to be used for ad-hoc queries or will the list of choices for users be limited? (iii) Define the SCOPE of the new information system. That is to say, determine which functions will be automated and which will remain manual. This will help to determine what information is going to be captured and stored in the database. (iv) Determine the method of data capture to be used. Are barcode readers going to be used? We need to know this to be able to determine which DBMS packages to select (given we are not going to program our own database management system). (vii) Determine performance metrics such as required response time and error tolerance. (viii) Determine the type of information to be stored. Some packages store graphics (like an identity picture) while other packages do not have this feature. (ix) Create a data model of the new information system environment. This means creating a data dictionary and entity relationship diagram, then converting the ERD into a data model. The data model is then normalized, to minimize the impact of errors caused by update anomalies. The normalized tables of a new database may then be "renormalized" to meet performance requirements. (x) Build some tables with a DBMS and do some testing…. AND SO ON….
Building information systems and databases is a complex business! It is best left to people called systems analysts who have the training and experience necessary to do this work.
This refers to testing that takes place through all the phases of a system development life cycle. There are many types of testing that take place. The following are a few important tests that are completed to see if a new system has any errors in it or not.
· System testing involves the designer doing the testing. He uses various techniques including black box and white box testing to ensure that every software function and procedure works correctly. He uses integration testing to ensure that the system works correctly when all the parts are put together.
· Acceptance testing is user oriented. During alpha testing users try out the new system under controlled conditions where they are observed by the system developers. Users have to decide if the system meets or exceeds their expectations. Beta testing is carried out by many users who are given the new software to try. Feedback from trial software users may help to uncover errors in the system.
· Performance requirements set at the start of the project can be checked by the programmer to verify that the system does as it is required to do.
Top down design
This is a system development technique whereby a large problem is broken down into small manageable units of work. Ideally each small part will have only one purpose (strong cohesion) and there will little or no effect on other units of work when one unit of work is changed (loose coupling). In reality top down design is only used for very simple applications. Bottom up design is an alternative that works fine for many types of problem. If the problem is well defined then a bottom up design is going to be more efficient since it likely that a new system can be constructed from a library of existing program functions and procedures.
A list of transactions. In a business this might be a list of sales for the day. At the end of the day the transaction file is merged with a master file to update such information as shop stock levels and year to date sales totals. One way of thinking of a transaction is that it represents a change to a database. Processing a single sales transaction will mean updating several database tables. For instance we might need to update a stock level table, monthly sales table and maybe a cashier sales table as well. Two important terms associated with transaction processing are commit and rollback. If all changes to all tables can be completed successfully then we can commit a transaction and changes will be made to the database. If for some reason not all changes can be made successfully then a transaction will be rolled back and the database will look as though the transaction was not applied to the database at all.
This is an error that occurs when we send information from one computer to another. It is quite common to send a packet from one computer to another only to find that it has been changed (corrupted) sometime before it reaches its destination. Fortunately, the computer operating system will check each packet that arrives to ensure that it still has integrity by performing a CRC (cyclical redundancy check). A CRC is a flash version of a check digit validation procedure.
A document that has been created by a computer to be used for data entry. It is a called a turnaround document because once it has been filled in by users it is then used for input back into the computer. An example of a turnaround document is the mark sheet that is filled in by your teacher. The mark sheet is generated by the computer, filled in by the subject teacher and then used for input back into the computer so that reports can be printed.
Uniform Resource Locator (URL)
Each site on the internet has its own unique address, called a URL.
http://www.brunei-bay.com is the URL for a website that can be found on the world wide web.
A computer system that is user friendly is going to have many of the following characteristics – (i) the user interface is intuitively easy to use (ii) processing meets or exceeds end-user expectations (processing is completed as predicted and in an acceptable time frame) (iii) Output is in a format that is acceptable (e.g. files, screens, charts or reports), provided within an acceptable timeframe and containing information at the level of detail required by the recipient (iv) data is accurately and safely stored (v) the system is flexible enough to be modified at short notice given the changing nature of IS environments.
Checking data entry for accuracy is called validation. A check is made to ensure that data meets criteria such as being of the correct type, being within a range if required and that data exists when it is supposed to. For instance, when we enter data about a person we might check that the day part of the date is between 1 and 30 for most months and between 1 and 31 for some other months. By doing this we are able to check data entry before processing takes place.
Variable length field
Most modern databases have variable length fields. The computer memory used when we enter an item of data into a field will equal the length of the data item. If we enter “Batman” into a name field then the size of our database table will only increase by about 6 bytes (the length of the word Batman). If our database was set to use fixed length fields then it could be that the field width has been set to 100 bytes. In this case, when we added Batman to the database the database would increase in size by 100 bytes. Clearly variable length fields help us to save storage space by reducing the size of our database tables. On the other hand, the database management software for variable length fields is more complex than that for fixed length fields. In general fixed length field databases are fine if the database is small in size or else if the data to be entered has a well defined size and format. The end of a variable length field is identified by a special character called a field end marker. The DBMS will look for the field end markers in a table to find out where one field ends and the next field or record begins.
This means ensuring that information that has been transcribed from source documents is the same as the original source documents. One technique used to verify input is to have the same input entered by more than one person. If the input files created by the data entry people are different then one of the data entry people has made a mistake which needs to be corrected. If the files created by the two data entry people are identical then the data has been entered correctly.
This is a computer representation of reality. A flight simulator is an example of a virtual reality environment. Some virtual reality systems require a person to wear a headset and special glasses.
Wide Area Network (WAN)
A WAN is a network that allows computers to connect to each other. It is a network that covers a large geographical area. The distance between computers is commonly several to thousands of kilometers.
Windows, Icons, Menus and Pointing devices (WIMP).
Most graphical user interfaces have WIMP features. Most people find it easier to interact with a GUI which has WIMP features than to interact with an alternative such as a command line interface.
v Microsoft Windows XP is a WIMP operating system.
v Microsoft MS-DOS is not a graphical user interface – it is a command line interface. MS-DOS does not a WIMP OS.
When a word is too big to fit at the end of the current line of text then the word is automatically placed at the start of the next line. The cursor is then positioned at the end of the new word, ready for the next key press.