WORD PROCESSING and DTP Word Wrap – automatically moves a word that doesn‟t fit at the end of the line, onto a new line. Text Wrap – forces text to flow around graphics in various ways. Formatting – changing the appearance and layout of the page and its text. Changing the Font (typeface design) or the Font Size. Changing the Style of the text e.g. bold, underline, italic. Changing line length – changing the left or right margins. Changing page length – changing the top or bottom margins. Changing line spacing. 1.5 double space Changing the alignment – left, centred, right or fully justified (sometimes just justified). Tabulation – using TAB stops to produce tables. Drop Caps – large decorative letter at the beginning of a paragraph spanning several lines. Headers and Footers – sections of a document at the top and bottom of pages used to apply master items to several pages. e.g. auto line number, date, captions, logos etc. Search and Replace – replaces text with different text anywhere in a document. Selective - asks before changing. Global - replaces all. Whole word only – will not replace parts of words. Spellchecking – highlights words not in its dictionary. Usually offers an alternative word. Can highlight names etc that are correct, since these are not always in the dictionary. Does not check the context of words so words like there or their can be wrongly used without being highlighted. Grammar Checker – highlights errors in the rules of a language. E.g. Capitalisation, subject-verb agreement, missing punctuation etc. Standard Paragraphs – commonly used paragraphs saved on disc. A letter is made up by combining various paragraphs from disc. Faster as no typing and no error correction. Standard Letters – Frequently used letter with blank space for name etc., saved on disc. Are reloaded and personal items added. Mail merge can be used to automate the adding of personal data from a database by inserting placeholders in the letter for the database fields. Junk mail is unwanted mail which has been sent out after being produced usually by mail merge. Companies sell mailing lists of potential customers to other companies who often send out junk mail. Tables – a facility to present information in an organised and clear way using rows and columns. Data can be easily inserted or deleted – usually easier than having to set tabs. Templates – Blank documents that are saved with format and layout information as placeholders. Any dummy text is replaced by the user. Wizard – part of a program that takes you through a series of instructions and questions to produce a document. Useful for inexperienced users. Printers – output devices for producing hard copies of documents Ink Jet - cheap, high quality printer on which ink is squirted onto paper. Ink can run if damp. Ink costs are expensive. Laser – Most expensive and best quality which uses a laser to charge paper and attract powdered ink (called toner). The ink is then heat sealed. Device Driver – a program installed on the computer which allows the computer to communicate correctly with any peripheral device such as printer, modem, CD-ROM drive, scanner. E.g. a printer driver provides full use of all the printer features, e. g. back to back printing etc. Standard file format – format of saving text so as to import into all applications e.g. plain text (.txt) (ASCII) or Rich Text Format (.rtf) SPREADSHEETS Spreadsheets Are made up of columns (with letters) and rows (numbered). Can have three types of entries – values (numbers), text and formulae. Formulae are used so that when values are changed, the spreadsheet automatically changes (updates). Cell B2 Column Tastie Row Tastie Cafe Formulae – see diagram above Formula in I3 is =H3*B3. This multiplies the contents of H3 by the contents of B3. Similar formula can be used for adding e.g. =A1+B1 or subtracting e.g. = A1– B1 or dividing e.g. = A1/B1 Functions such as SUM can be used to carry out calculations Formula in C9 is = SUM(C3 :C7) or =SUM(C3..C7) This adds up the contents of all cells from C3 to C7 (i.e. C3, C4, C5, C6, C7) Other functions include AVERAGE, MAX and MIN e.g. = AVERAGE(H1:H7) would find the average value of the contents of the cells from H1 to H7, =MAX(H1:H7) would find the biggest (or maximum) value in the range H1 to H7. The IF function IF(test, value if true, value if false) In the example shown, the test is whether the total sales is less than £10,000. If the result of the test were true then C2 would have contained 10%. In this case the test gives the result false and so the value in C2 is 15%. Formatting the Spreadsheet The attributes of cells can be changed o The width of columns or the height of rows The attributes of the text can be changed o The style e.g. bold o The font e.g. Arial o The alignment e.g. centre o etc. The attributes of the numbers can be changed o The number of decimal points (precision) o Currency format e.g. £25.50 Inserting or Deleting Rows or Columns can be removed or added at any point. Protecting Cells (Locking Cells) Cells can be locked to prevent them from being changed accidentally Replication The contents of cells can be copied into other cells either by copy and paste or fill down or fill right. Relative References When formulae are replicated, the formula is automatically changed to take account of the new column or row. This is what happens by default. Absolute References When formulae with absolute references are copied, the formula does not change. It stays exactly as it was in the original cell A $ sign is used to signify which parts of a formula are not to be changed. E.g. If the formula = B4*B$1 is copied down a row from C4 it becomes = B5*B$1 Absolute Relative Formula replicated from C4 to C5 Charting Spreadsheet data can easily be shown on a chart. Some charts that can be created are pie chart, bar chart, line graph etc. You must select the data in the spreadsheet before making the chart. Data used by charts Pie chart Chart title Legend Data labels Bar Chart Chart title Legend Y - axis labels X - axis labels DATABASES Structure – A database consists of files. Each file consists of records. Each record contains fields. For example: 14 1213 11 10 7 89 56 34 12 Name: Name: J. Blog J. Bloggs Each record has 3 Class: Class: FIELDs :- 1K31K3 Name, Class and Age Age Age 12 12 FILE of 14 RECORDs One RECORD per person Record 1 is for J. Bloggs Editing – making changes to the database. Inserting a new record. Deleting a record. Amending a record – making changes. We may make changes to the format of the record Adding a new field Deleting a field Amending a field – e.g. changing its data type Search – (or Find or Query) A rule is used to find just certain records. A Simple Search would use a rule such as Class = 1K3 to find everyone in 1K3. A Complex Search uses a rule made up of two or more simple rules joined by AND or OR e.g. (Class = 1K3) AND (Age > 12) would find everyone in 1K3 who was older than 12. In rules, use the following contains = contains is exactly equal to > is greater than < is less than >= is greater than or equal to <= is less than or equal to <> is not equal to Sorting – Puts the records into some order. A Simple Sort sorts on one field e.g. sort on the name field. Sorts can be in ascending order (A..Z or 0 .. 9) or descending order (Z .. A) or (9 .. 0). Complex Sorts sort on more than one field. E. g. To sort the pupils into classes, and have them in alphabetic order within the class, sort on the class field in ascending order and name field in ascending order. To sort the classes alphabetically by surname, there would have to be a field for surname or names would have to be entered surname first e .g. BLOGGS, Joe Reports – A report is a selection of the database, presented in a way that makes it easy to understand. The process is : 1. Search for some records using a rule. 2. Sort them into some order. 3. Choose the fields to be displayed 4. Choose the format e.g. in columns. 5. Display this layout on the screen or print it out. Creating a new database Decide on Fields and their data types e.g. name (type text), age (type integer) Some fields may be calculation (or computed) fields. These field values are calculated automatically using the values in other fields. The calculation uses a formula e.g. cost = number bought * cost of item Here, cost is the calculation field. Decide on one key field which has unique entries to identify each record. To calculate the size of the database Calculate the size of each field Add to find size of a record Multiply by number of records Decide on suitable backing storage. Computers and the Law Data Protection Act – designed to protect people from having false information about them stored on an automated system, such as a computer database. Everybody has the right to:- see what personal data is being held about them (they may have to pay for the privilege!) have the data corrected if it is wrong. These are called Subject Access Rights. data controller is the person in a company who decides how the personal data is going to be used. Organisations holding the data have to:- register so that an entry is made in the Data Protection Register. This is updated every year. let you see data about yourself but nobody else . make sure the data is secure so that others don't see it. keep the information up to date. tell you why it is being held and not use it for any other purpose. These are called the Data Protection Principles. There are some exceptions to the Data Protection Act:- certain organisations such as the police and Inland Revenue (tax authority) can hold data about you, without obeying these rules. Computer Misuse Act – makes the following activities criminal offences. (A jail sentence is possible.) Gaining unauthorised access to computers – (hacking) The writing and spreading of computer viruses. (A virus is a program which hides on a computer (where it may or may not cause damage) and passes to other computers by attaching itself to Emails or discs. Antivirus software is designed to protect computers against viruses.) Copyright, Design and Patents Act – makes it illegal to copy a file without permission from the owner or copyright holder. (A fine is possible). This may be by Using software without the proper licence Downloading text, images, music etc from the Internet and using them without saying where you got them or without the owner‟s permission. INTEGRATED PACKAGES Integration - For a package to be classed as integrated it must: allow easy sharing of information between different applications. For example, you might want to transfer some text from the word processor to a separate graphics document or link a word processor to a database. and have a common Human Computer Interface (HCI) in each application. That is: each application should have a very similar look and feel (e.g. the arrangement of common menu items on the same menus in different applications) so that it is easy to learn how to use the different sections. If you learn a command in one application, it will be used in an identical way, in another. (See over page for more on HCI.) Integrated Package – is a program that is made up of several commonly used types of general purpose packages. When an integrated package is opened all the parts are loaded into memory. The types of application which are included in integrated package might be :- a word processing program a spreadsheet program a database program graphics programs Integrated packages generally do not have all the features that separate applications have and are cheaper than buying a whole set of separate packages. They are good for beginners. Examples are AppleWorks or Microsoft Works Software Suite – is a set of programs produced by the same software company. Each program is loaded separately as needed. There is usually integration within the software suite programs. Examples are Microsoft Office or Lotus SmartSuite. Non – Integrated Packages Although with modern operating systems it is usually possible to transfer data between any two applications, if the two applications are not integrated often some features of the data will not transfer correctly e.g. text may transfer but lose all its formatting. Standard File Formats Standard File Formats make it easier for data to be transferred between different computers or different packages. Text (txt) – the most common form of text file contains just the ASCII values of the characters making up the text. There is no formatting. Rich Text Format (rtf) – in addition to the text, this format contains information about the font, size, colour etc All word processing packages would be expected to be able to open plain text files or rich text files. Static and Dynamic Linking When data is transferred from one document to another, the linking can be static or dynamic. Dynamic Linking means that if the original data is changed then the shared version also changes. E.g., if data is linked from a spreadsheet to a graphic document, say a pie chart, then if figures in the spreadsheet change, the pie chart is immediately updated. Static Linking means that if the original data is changed, the linked data remains unaltered. Mail Merging – requires integration between word processor and database. Data is transferred from a database to a standard letter in a word processing document. Create standard letter. Link to the database. Insert placeholders in the standard letter for data from fields in database (e.g. name and address) Search the database as required. Do the Print Merge so that letters are printed to everyone selected in the search. HUMAN COMPUTER INTERFACE (HCI) HCI - how the user and the computer communicate. User friendly - interfaces which are easy to use and may provide: Online help – help provided by the computer as a program is running Online tutorial – a computer based set of lessons to teach users, step by step, how to use programs. Graphical User Interface (GUI) – Uses a display which provides pictures. Some (older) computers still provide a text only display e.g. older cash machines. WIMP environment Windows Icons Menus Pointer – controlled by a mouse, trackpad etc. Easy to use for inexperienced or experienced users, but sometimes slow for expert users who may find it tedious to go through many menus and dialogue boxes to get to the option they want. Virtual reality - Making the interaction with the computer appear to be similar to real life. There are many different degrees of reality from a driving simulator* on a normal PC to a flight simulator costing millions of dollars used to train pilots. Specialist hardware such as headsets with monitors for each eye and special gloves or suits can be used. Used in games, or in training situations eg training surgeons, pilots etc. * Simulation – a copy of reality on a computer Boeing 777 Flight Simulator: Cost $30million Specialised User Interfaces Different groups of people might use special HCI‟s. e. g. disabled users may have voice recognition systems or military users may have simplified input systems for use in battle. Standard Grade Computer Systems Revision Notes Low Level Machine o A computer has a processor which carries out instructions fetched from a program in its memory. o A computer processes data. This has no meaning for humans who have to put it into context. Then it becomes information. (3.4, 3.6, 3.2 is data: lengths of fingers in cm - 3.4, 3.6, 3.2 - is information) o The computer will have input devices, output devices and backing storage (where data and programs can be stored when the computer is switched off). Input Processor Output save load Backing Storage o Any device connected to the processor is called a pe ripheral. o The processor in modern computers is a microprocessor chip. It is connected to main memory (more chips) and input or output devices by wires which carry instructions and data to and/or from the microprocessor. Main memory Registers ALU Control Program 1 data Unit Micro - Program 1 processor o The microprocessor consists of: Temporary storage memory called registers. Arithmetic and Logic unit (ALU) which does any arithmetic needed and makes decisions (the logic part) by comparing values stored in its registers. A control unit which decodes program instructions and sends signals to memory and peripherals controlling the movement of data around the computer. o Memory can be ROM (Read Only Memory) or RAM (Random Access Memory) ROM RAM Cannot be changed Can be changed Used to store start-up program Stores users‟ programs or work for Windows Contents not lost when computer Contents removed when switched off computer switched off Memory is divided up into units called locations, each of which has a unique address which is used to identify where data is stored. The amount of data which can be accessed by the processor at one go is called a word. Usually one memory location holds one word. The amount of data which a word can hold is measured in bits or b ytes. A bit (binary digit) is an‟ON‟ or an „OFF‟ - ‟1‟ or a „0‟. 8 bits make up a byte. 1024 bytes make up a kilobyte (kB) 1024 kB make up a Megabyte (MB) 1024 MB make up a Gigabyte (GB) 1024 GB make up a Terabyte (TB) One byte of memory can store one character such as „F‟ or‟A‟ or‟p‟ or‟!‟ or‟9‟. Data Representation o Whole numbe rs (integers) – integers can be stored in binary representation. For example the binary number 10011100 represents 128+16+8+4 = 156 in decimal place 128 64 32 16 8 4 2 1 value 1 0 0 1 1 1 0 0 o Text can be represented using ASCII (American Standard Code for Information Interchange). This is an internationally agreed coding that uses 7 bits to encode capital or uppercase letters (e.g. M, J), lowe rcase letters (e.g. m, j), numeric digits(e.g. 9, 5), punctuation(e.g. !, &) and some control codes(e.g. beep, start sending data etc.). Being an American code, some European characters are not included so sometimes 8 bits are used, the extra characters being for example foreign characters (e.g. é, β) and the £ sign. o Bitmapped Graphics. Black and white bitmapped graphics are made up of dots called pixels (picture elements) which can be on (1) or off (0). The array of pixels can be represented as an array of 1‟s and 0‟s called a bitmap. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o Calculating the size of graphics - The size of the stored graphic can be calculated by working out the number of pixels in the graphic. This is then equal to the number of bits used to store the graphic. In the case of the graphic above, The number of bits is 24 x 6 = 144 bits. Since there are 8 bits in a byte, the size of the graphic is 144/8 = 18bytes. Input Devices – devices that allow data to be entered into the computer trackball o Keyboard – for entering text. o mouse – controls pointer on the screen. o trackball, trackpad – used on laptops where there may be no flat surface to use mouse trackpad o graphics tablet – used with graphics programs. The user ball can draw or write on the tablet and input is transferred to computer. o touch sensitive screen – used in public places where a mouse would not be suitable Graphics tablet o joystick – often used with games joystick o scanner – used to input pictures or documents. Scanned using laser light. Optical Character Recognition (OCR) may be used to obtain editable text from the picture. o digital still camera – resolution measured in Megapixels o digital video came ra – for inputting movies for editing etc. o we bcam – low resolution video camera used to provide pictures or video for the web. webcam o microphone – connected to sound card allowing sound e.g. voice to be entered o specialized input devices for: disabled users military etc o virtual reality – see separate sheet on HCI Output Devices – Devices that provide information to the user such as text, graphics, movie or sound. o Monitor (sometimes called a VDU – Visual Display Unit) Laptop and Handheld computers have LCD (liquid crystal display) screens CRT monitors are gradually being replaced by LCD ones on desktop computers. LCD monitors used on computers are TFT – thin film transistor – giving high quality colour display. Monitors are connected to the graphics card in the computers which supplies the correct signals. o Printer Laser – high resolution (measured in dpi – dots pe r inch), quiet, fast (measured in ppm – pages per minute), but good colour laser printers are expensive to buy. Inkjet – not quite as good resolution, nor as fast. They are good for printing photographic quality cheaply. Their running costs are marginally more expensive than laser printers plotter o Plotter – used in Computer Aided Drawing (CAD) to give accurate diagrams or plans. Can give large size print outs. o Louds peakers – give out the sound - mono, stereo or surround sound. o specialized input devices for: disabled users military etc Backing Storage Devices – Devices that store data when the computer is switched off. o Magnetic tape - uses sequential access (data is continuously read from the tape as it winds on until the data needed is reached. This is too slow for most interactive processing.) Tape is mostly used for backup. Can store up to 30Gbytes of data and are relatively cheap. o Floppy Disk – uses direct access (sometimes called random access) - data can be obtained directly from the medium by going directly to where it stored. Floppy disks have limited capacity (1.44Mbyte) and data transfer rate is slow. o Hard Disk – uses direct access. Can store up to about 500Gbytes and data transfer rate is very high. o CD (Compact Disk) – uses direct access. Can store up to 800Mbytes. Data transfer rates are faster than from floppy but not as high as hard d isk. CD-ROM (Read Only Memory) – Data is put on it when it is manufactured and cannot be changed. CD – R (Recordable - write once) – Users can save data on to it once and then the data cannot be changed, only read. CD – RW (Rewritable) – Users can read and write data many times. o DVD (Digital Versatile Disk) - uses direct access. At present, can store up to about 19Gbytes. Data transfer rates are faster than from CD but not as high as hard disk. DVD-ROM (Read Only Memory) – Data is put on it when it is manufactured and cannot be changed. DVD – R (Recordable - write once) – Users can save data on to it once and then the data cannot be changed only read. DVD – RW (Rewritable) – Users can read and write data many times. o USB Flas h Drive – This is a solid state device with no moving parts and uses direct access. Can store up to about 2GB. Very fast access. Types of Computer o Desktop – with system unit and hard disk, keyboard, mouse and monitor. o Laptop – with system unit and hard disk, keyboard, trackpad and TFT monitor. o Palmtop – usually no proper keyboard, touch sensitive TFT screen and uses a stylus. Some have handwriting recognition. No hard disk but many have extra solid state card storage, o Mainframe – very powerful processor, large hard discs. Usually multi-access system allowing access from terminals Operating System – This is a program which runs as soon as the computer is switched on. It provides the following features: o HCI (Human Computer Interface) – Modern windows system have a GUI provided by the OS. (See separate sheet on HCI) o File Management System Deals with the storage of files on backing storage. The system must keep note of where files are stored, their names and the free space on the disk. Modern operating systems provide a hierarchical filing system allowing directories (folders) within directories. This allows files to be stored and found more easily. o Memory Management System Keeps track of where programs and data are stored in main memory to make sure that data is not overwritten. o Error reporting The OS HCI will report back to the user with sensible messages if there is a problem. Examples are: Disk full. – from the file management system, A file with that name already exists. Do you want to overwrite it? – from the file management system Out of memory. – from the memory management system o Inte ractive System with background capability Modern OS‟s allow several programs to be running at the same time. The user may be working on one program, while another is running in the background, using the processor as it becomes available (e.g. between keystrokes). The processor switches so quickly from one program to another and back again that the user does not realise. Example: the user could be working on one document while another is printing. o Device Drivers Each input, output or backing storage device needs a program to allow all the features of the device to be used. Without a device driver program it will not operate. The OS uses these programs when data needs to be sent to or obtained from the device. Examples are – printer drivers, driver for a scanner etc. Different Type of Operating System o Real time operating system This type of operating system would be needed for control situations e.g. an industrial process. It has to be fast to respond to changing conditions, so that they do not get out of control. NETWORKS AND COMMUNICATIONS Network –computers linked together so they can send and receive data. Local Area Network (LAN) – the network operates in a small area, e.g. a school or office block. The computers are linked either by cables or wirelessly. Advantages of LANs Users can share peripherals such as printers Users can share data files such as database files Users can communicate using email. Cables Copper wires – usually unshielded twisted-pair cables allowing speeds up to 1Gbit per second Fibre optic – made of fine strands of glass that carry pulses of light. This transmits at high speed and is not affected by other electrical appliances. Wireless Data is transmitted using radio waves There is no need for any wiring so computers can be used anywhere within range. Network Interface Cards (NICs) A NIC allows your computer or printer to connect to the network It packages data sent from the computer into a format suitable for the network. It takes data sent over the network for its computer and passes it to the processor. Client/Serve r Network A client is a workstation computer on the network. A server is a special computer on the network which controls some of the network resources used by the workstations. E,g. A fileserver holds users data or applications software files. A printserver organises printing in the network Wide Area Network (WAN) – the network operates in a large area, e.g. across towns and world wide. The computers are linked using telecommunication links such as phone lines. Uses of WANs Email Accessing information Financial transactions etc Multi-access computers – powerful computers (often mainframes) that allow many users working at terminals to: access the system at the same time share the processor at the same time. (Each user is given a short time slice of the processor. It happens so quickly that users do not realise that they haven‟t got the whole of the processor‟s time.) share memory and data on disc Terminals – many are connected to the multi- access computer May only consist of a keyboard and monitor as the multi-access computer provides, processor, memory and backing storage Used to run programs on multi-access computer and view results Security on Networks – to prevent hackers gaining access to data Physical security – locks on doors and/or computers. Software security user ID‟s and passwords. Each user can have different levels of authorisation. Advanced ID methods include finger print or iris scanning Encryption – data is encoded (jumbled). This means that a hacker breaking into the network system will not be able to read the data unless he/she has the encryption key code. Electronic Communication Text messaging Text messaging (SMS) as used on mobile phones „Instant Messaging‟ – sending text messages between computers e.g with MSN Messenger E-mail – messages sent from computer to computer. They are stored in a „mailbox‟ until the user downloads them to his or her computer. Advantages Fast – it takes seconds or minutes to arrive Cheap – no direct payment to anywhere in the world (But you have to pay for a connection to the Internet.) You can send multiple copies Can add files (e.g. WP documents or spreadsheet files) as attachme nts. Password protected Disadvantages Viruses – unwanted programs that can cause damage to your computer may be attached to email. Spam – lots of junk e-mail may arrive. Netiquette– a set of rules laying out how people should behave when using email or the network E.g. do not use all capitals – this is shouting do not use bas language. The Internet – enables computers and computer networks world wide to connect to each other Online/Offline When referring to the Internet, online means that your computer is connected to the Internet, ready to receive or transmit data. Offline is when it is not. Inte rnet Ready Computer needs A telecommunications connection using a modem and a broadband or dial- up connection An ISP (see below) Software (at least a web browser) (Some mobile phones or Palmtop computers can also access the Internet for email or even display web pages.) Web browser Web page is written in html (HyperText Markup Language) using tags (commands) to describe elements on the page. (e.g. <br> is the tag that gives a new line) The web browser fetches the html and interprets the tags to display the web pages. In the browser you can move from page to page using back button or hyperlinks. A hype rlink links to a new page or new place in the same page when clicked. It contains all the information to find and display the page. Inte rnet Service Providers (ISPs) Provide access to the Internet for ordinary users. User‟s computers must access the ISP‟s computer with a user ID and password each time they go onto the Internet. Users usually pay a monthly charge. Most ISP‟s provide mailboxes and web space for users web pages. Dialup connections uses the ordinary phone line to dial the ISP and connect to the Internet (max speed 56kbits per second) Broadband connection is a high speed link up to about (in 2006) 8Mbits per second download and may use a digital telephone line or cable. Choose an ISP using the following: Price Connection Speed Reliability of connection Download limits etc. Software Downloads Freeware – This is free software but the author still holds copyright. You can give copies away, but must not sell it or change it. Shareware – Relies on people‟s honesty to pay for it if they decide to keep using it after trying it. Commercial Software – bought over the Internet is similar to buying it in a shop. Generally you can use it on one computer only. Breaking these licence agreements is against the law. – The Copyright Designs and Patent Act. Video Conferencing Using a computer network to send sound and video data to enable people in distant locations to have a face-to-face meeting. Webcams and microphone capture pictures and sound and speakers are needed to broadcast the sound. Saves businesses time and money – no flights or hotel bills. Social, Legal and Ethical Issues Social Issues Not everyone world wide has access to the Internet and the information which is available there. (In fact most people in the world do not have access to a phone.) Some people become isolated by spending too much time on the computer and do not mix socially. Legal Issues People use networks to commit crime e.g stealing from people‟s bank accounts, illegally copying music/software. (The Data Protection Act, the Computer Misuse Act and the Copyright Designs and Patent Act cover this area.) Ethical Issues – (the right ways and the wrong ways of using networks) Networks bring benefits to society as powerful communication tools but on the other hand there is anti-social use of networks including stirring up hatred, committing crimes etc. You all have signed an “Acceptable Use Policy” as a code of conduct when on the network. We have to make sure the positives outweigh the negatives. COMMERCIAL DATA PROCESSING Data – numbers, characters and symbols which have no meaning for humans. Information – When you know the meaning of the data, it becomes information. Large Business Companies like supermarkets, airlines and banks have to deal with a large amount of data. They need fast processing and must be able to handle thousands of tasks at the same time from lots of people. Often a mainframe computer is used to do this. This will have terminals, (as a minimum keyboard and screen) connected as a WAN. Data Processing Cycle – Data is collected and prepared for use by computer using methods given below. It is then input and processed, before being output to a screen, to paper or stored in a file. Data Input Bar code. E.g. on supermarket items where the barcode contains a code for the item Magnetic Strip. E.g. on a bank debit card where the account number is held on the strip. MICR – Magnetic Ink Character Recognition. E.g. on bank cheques to hold the account number and bank code. Helps prevent forgery. Smart Cards – These have their own processor with memory. They connect to the computer either by metal contacts or wirelessly. Data can be read from or written to them. The processor makes them very secure to try to prevent fraud. Mark Sense Cards – Marks are automatically sensed by the reader. Optical Mark Recognition (OMR) allows pen marks to be detected e.g. on lottery cards. Some other methods allow pencil marks only to be detected. OCR – Optical Character Recognition allows text to be scanned in and converted to a word processor document. Difficult to detect difference between e.g. rn and m or cl and d. Handwriting Recognition is even more difficult than OCR. Used to detect Postcode on letters or (usually with special form of writing) as input to a handheld computer. Speech Recognition. Allows users to speak to computers and have it converted into text. Difficult to detect correctly different accents etc. without training the program. Making Sure Data is Correct – Error checking. Verification. Checking that data is transferred from one place to another without error. Can be checked by typing twice and comparing input, by a check digit or a checksum. Validation. Checking that data is accurate and reasonable. Can check that data has the correct number of characters (a length check) or by a range check (e.g. that date for April is between 1 and 30) or by a check digit. Check Digit. This is a digit added to a number, produced by a calculation on the original digits in the number. When the number (with check digit) is entered into the computer, the computer does the same calculation to recalculate the check digit. If it does not agree with the entered check digit there is an error in the number. Single Entry Multiple Use Data is entered once and stored on a central computer where it can be accessed by different departments for different uses. This prevents differe nt departments having different versions of the information. Data Processing . Data is stored in files, made up of records. Each record contains a number of separate fields. Data can be stored using Direct Access (Random Access) e.g. on disc allowing fast access or using Sequential Access (Serial Access) on tape, where each record must be accessed one after the other. Data can be processed by o Batch processing where the data is collected together over a period of time and then processed without human interaction o Inte ractive processing where the data is processed and the results returned to the user immediately. o During processing, files stored on the computer system may be updated. Protecting Files from Damage o Backup – a copy of the data is saved. The backup should be stored in a different location in a fireproof safe. o Computer crime – To prevent unauthorised access to files, physical security (e.g. locks etc), passwords and encryption may be used. Customer Lists Companies sell mailing lists to other companies. The other companies can use a mailshot to target customers for sales by using Mail Merge. This results in people getting “Junk Mail”. E-commerce (electronic commerce) This is conducting business on-line, such as buying and selling items or services over the Internet and paying for them by moving money electronically. This involves on-line shopping and on-line banking. Advantages/Disadvantages of on-line shopping Advantages for companies o Cheaper as don‟t need catalogues and need only one office not lots of shops. Advantages for custome rs o Shop is open 24 hours per day o Often more items available than in shops. o Some websites allow you to compare prices between sellers. Disadvantages o Bank card fraud o Problems receiving goods – often no one home when goods arrive. o Time spent returning goods if they do not fit or are not wanted. Electronic Point of Sale (EPOS) Terminals The checkout at a store is the point of sale terminal. At EPOS terminals the checkout is part of a computerised system. The laser scanner at the checkout reads the barcode and sends the code to the computer. Here the code is used to find the description of the item and its price. This is sent back to the checkout to be printed on the receipt. As part of the stock control system, whenever an item is sold, one is subtracted from the number of the items in stock and when the number goes down to a certain level, more items are ordered by the store (automatically). Advantages of EPOS include o Customer given itemised receipt. o Automatic reordering stops items running out. o Stock checking much easier. o Store does not need to label every item, only the shelves. o Management can check how fast checkout operators are working. Disadvantages of EPOS include o Initial cost. o Unable to serve customers if computer system stops working. o If computer programmed with wrong price, difficult to notice. Electronic Funds Transfer (EFT) EFT is a method of paying using a debit or credit card without using cash. When paying at a checkout, using such a card, money is transferred electronically from the customer‟s bank account to the store‟s account. This is called Electronic Funds Transfer at Point of Sale (EFTPOS). Advantages of EFTPOS include o Customer does not need to carry cash. o Store does not hold as much cash – less likely to be robbed. o A lot less paperwork for the store and less cash to count. Disadvantages of EFTPOS include o Initial cost. Cash Machines (ATM’s) Money can be withdrawn using debit or credit card and a PIN (personal identification number). The credit card holds the user‟s account number, in the magnetic strip or chip on a smart card Advantages include o Customer can get cash anytime. o Bank needs fewer staff, saving wage bills. ROBOTICS AND AUTOMATED SYSTEMS What are they? – no agreed definition, but let‟s assume here: In an automated system a computer sends data to and receives data from other devices in the form of electrical signals. The response speed often needs to be very fast. This is real time processing and is needed in many speed critical systems e.g. controlling aeroplanes or nuclear power systems. An embedded system is a computer system built into a machine of some sort usually to provide a means of control. (The user probably does not realise that there is a computer there). E.g. in washing machines, vending machines etc A robot is an automated system, which can be reprogrammed to do different tasks. Sensor – most automated machines have sensors. These convert changes in the environment into electrical signals, which are sent back as feedback to the computer in the machine, which will then react to the signal. E.g. a heat sensor in a washing machine converts changes in temperature into electrical signals which are used to control the water heater. Robots can have all sorts of sensors e.g. pressure (touch), temperature, sound, ultrasound etc. Arm robot – see diagram. The tool is the “hand”. It can be a gripper, welding tool, paint spray etc These are stationary robots, working in a fixed place e.g. an assembly line. Programs can be stored on disc, tape or other backing storage. Mobile Robots Diagram 1 Usually on wheels or tracks, but some can also walk, swim etc. Used, for example, to carry heavy materials, explore the seabed etc. Usually the program is stored in ROM. Intelligent Robots – some robots show AI (Artificial Intelligence). They can make decisions or adapt behaviour based on signals from sensors monitoring their environment E.g. with a vision sensor, they can recognise the position of an object and change its movements to spray paint it correctly or fit it correctly onto another part. Teaching Robots – This is the term given to programming them. Programming by example (“Follow me”). E.g. the human operator moves the robot arm to spray a car. The movements are stored in memory as a program and can be repeated. This method of teaching cannot be used in dangerous environments. Using a computer keyboard or a keypad to type the program, often in a special purpose high level programming language, called a control language. Guiding Robots – Two examples are given below White Lines – The robot uses a light source and light sensors to follow white lines painted on the floor. The light shines down on the floor and if it hits the white line reflects back to the two sensors. If the robot goes off to one side, light will be reflected from the white line to one sensor only and the control program turns the robot to bring the light back above the line. Magnetic Guides - In a factory, electrical cables are buried under the floor. The robot has a magnetic sensor which it uses to follow the magnetic field produced by electrical current flowing through the cable. Interfaces This is a device which is connected between the processor and any peripheral ( a device outside the c.p.u.) to compensate for differences between them For example the device connected to the processor might supply high voltages, which would harm the processor if there were no interface, or the type of signal might not be recognised. Analogue and Digital Signals An analogue signal can take any value between limits. E.g. the temperature of the air is an analogue value. Digital signals are restricted to certain values and cannot go in between them. For example a digital watch which only stores time in seconds, cannot be used to read the time to 0.1 of a second, while an analogue watch second hand sweeps through all values. Computers store digital values and use digital signals An Analogue to Digital Converter (ADC) is an interface that changes analogue signals into digital signals. This is needed when a signal comes from a sensor to the processor. A Digital to Analogue Converter (DAC) is an interface that changes digital signals into analogue ones. This is needed when the computer is used to control a piece of machinery. Computer Aided Design (CAD) Special CAD software – a type of graphics software – is used for design. Features of CAD software include Libraries of shapes Automatic production of 3D views Production of “Walkthroughs” Automatic dimensioning (putting sizes on the drawing) Rendering of surfaces (putting surface texture on objects) dimensioning Computer Aided Manufacture (CAM) Using computers to control machines used in the making of goods. Computer Aided Design and Computer Aided Manufacture (CADCAM) When design is done on the computer and the design is used to produce the program, which controls the machine used in the manufacture of the item. Features of Robotic or Automated Systems Need few human workers - redundancies. People had thought that humans would have increased leisure time but this is yet to happen. They are capital intensive (high initial cost) rather than labour intensive. The initial costs are high but the running costs are much less than workers wages. Robots more accurate than humans. Humans need retrained and jobs may be completely different. Jobs left for humans can be less skilful – de-skilled. Robots can work steadily 24hours a day, seven days a week. Robots can work in dangerous environments. Safety precautions need to be taken to protect workers in areas where robots operate. E.g. flashing lights, sirens on robots, bump sensors so that robot stops if it hits anything etc. Before introducing robots, a system analysis needs to be undertaken and the workplace redesigned to make it more efficient for the robot production and for safety of remaining workers.