IPT HSC Summary


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IPT HSC Summary

  1. 1. HSC Information Processes & Technology Summary SheetsIPT HSC Summaries Pg. 1 Patrician Brothers College 2010
  2. 2. Schemati c Diag rams: Entity- Relationshi p diag ram ( ER D) Normal isation Data Di ctionar y Distributed database Calculated Field two- phase commi t Field N ame Data Type Field Si ze Descr ipti on Database Manag ement Fil e Recor d Seq uential access System: Field Data modelli ng Dir ect access School database Character Index RTA database Keys Schema Video Hir e database Sing le Key Entity Librar y database Composite Key Attri bute Accessing Data Pri mary Key Tupl e Transacti on Processing System Relati onship Secondar y key DBMS Tasks: Decision Support Systems 1:1, 1:many, many to org anising the data via data dicti onary Expert Systems many Shows r elationshi ps Manag ement i nformati on Systems Non-Computer method Foreig n Key Checks for data entry err ors Office automation systems Computer base method Tabl es All ow changes of DB str uctur e Examples Forms Flat File D B Restri cts access if needed Types & Purposes Or g anisati on of data Shows perfor mance of DB into informati on Or g anisati on Relati onal DB Anal ysis of Hyper text Methods Onli ne stor ag e infor mation to gi ve Hyper medi a Unifor m Resour ce Locator Stor yboar d Offli ne stor ag e knowledg e HTML har d disk optical disk Characteri stics Infor mation Database Manag ement r emovable car tri de Systems & mag netic tape Systems Databases Stor ag e M edia fl ash card Issues Stor ag e & Retr ieval Other Encr yption Querying Data Source Infor mation Asymetr ic encryption Query by Example Emerg i ng Technolog ies: Processes Symmetri c encryption Relati onal opertor s Smart Card Log i cal oper ator s New DB softwar e / strateg ies Displaying Backup/Securi ty Wi ldcar d char acter s Repor ti ng : Data secur ity SQL - > Accur acy of D ata: Str uctur ed Quer y Hardcopy, softcopy Physical secur ity Sorting data Data validation via - > Lang uage Repor t Header Fir ewal l Ascending r ang e check Pag e Header Data Encryption Descendi ng li st check Detail s Closed Cir cui t TV type check Pag e Footer Restri cted Level s of check dig it Repor t Footer Access Data Integ r ity Pri vacy Desig n of Di ffer ent Repor t Vi ews: Hyper medi a & Headi ng s - > Purpose Sear chi ng Layout - > tabular, col umn Sear ch Eng i nes ( Web) Access to Data Index Text Balanced Consi stent styles Dir ectories Sear ch robot Calculation of Storag e: Columns have heading s Total Fi el d size of each field X White space used well Data warehousing number of r ecor ds = number of bytes Pag e numbers/date i ncluded Data mi ni ngIPT HSC Summaries Pg. 2 Patrician Brothers College 2010
  3. 3. Concept: Information Process - Collecting Concept: Information Process - Organising Concept: Information Process - AnalysingDefinition: involves deciding what to collect, locating Definition: involves the modification of data by Definition: involves the interpretation of data,it & collecting it. arranging, representing & formatting data. transforming it into information.Summary Points: Summary Points: Summary Points:§ data formats may be numbers, images, text, forms § digitising is the process of translating data into § information is processed raw data, it has beenaudio, video binary digits that can be stored & used by a computer. ordered and given meaning to people.§ input devices: pointing devices, scanners keyboard § each type of data must be represented digitally § searching, sorting, modelling (simulations)digital still cameras / video cameras, microphones, text: ASCII; images: bit-map (jpg, gif) ‘what if’ predictions, charts allows analysingoptical recognition devices (OCR). audio: sampling § application software organises data. Paint / draw,§ operating system is used to interface with the hard multimedia, word processing, desktop publishing,ware collection device & the user spreadsheet, database, slide shows.Example: Example: Example: Flatbed scanner may be used to digitise an image. Powerpoint may use text, images, video & audio. Each Counting the total number of students who doThe operating system connects to the scanner. datatype is processed differently. Biology in Year 12, sorting in alphabetical orderConcept: Information Process – Storing / Retrieving Concept: Information Process - processing Concept: Information Process – Transmitting / ReceivingDefinition: involves saving data & information for Definition: involves the manipulation of data & Definition: involves the transfer of data & informationuse (storing) and obtaining data and information information. from within & between information systems.that has been previously saved (retrieving)Summary Points: Summary Points: Summary Points:§ writing and reading data to hard disk § speed of the cpu determines how quickly data can § parallel transfer: like a multilane highway be processed. Current speed 3 gigahertz (clock speed) serial transfer: like a single lane highway§ direct access: access to data like a CD § images take a lot longer to process as compared § includes the use of networks and modem. sequential access: access to data like a casessette to text due to the amount of memory / storage an music tape. Used in backup magnetic tapes image data type takes§ floppy disk, usb flash drive, optical disks, zip disks § at least always transmits to a printer to produce§ hard disk storage is in gigabytes generally. a hard copy.Example: Example: Example:A word document can be saved to an Apple machine, Editing of a video takes up a tremendous amount of When one prints: from within information system.it is formatted as an Apple file, saved to the hard drive. processing power to edit as well as storage of raw When one sends an attachment via email: it isThe file is accessed directly. The entire hard drive can video footage. The final video is compressed using transmitted between information systems.be backedup to magnetic tape using sequential access less storage but needs to be unencrypted when run.IPT HSC Summaries Pg. 3 Patrician Brothers College 2010
  4. 4. Concept: Information Process - Displaying Concept: Information System Definition: a set of information processes requiringDefinition: involves the output from an information participants, data/information, & info. technology. Itsystem to meet a purpose. is created for a purpose, operates in a particular environment. It performs the 7 info. processes.Summary Points: Summary Points:§ includes monitors, printers, speakers & plotters § info technology includes software & hardware§ each application software displays data § participants are direct users of an info. system. A person using the screen at an ATM is a direct user at the moment. § A person using a clerk within a bank would be an indirect user at the moment.Example: Example:a. Word processing draft shown on a monitor. Use of ATM, eftpos, library cataloguing system. RTAb. Edited music listened to on speakers. licensing, Netmeeting, web ordering, SMS, voice mail, video mobile phoneConcept: IS Characteristics: organisation of data into Concept: IS Characteristics: analysis of information Concept: Type of IS: Transaction Processing Systeminformation (IS = Information System) to give knowledge. (IS = Information System)Definition: data re-arranged so that it may be useful Definition: information is processed raw data Definition: collects, stores, modifies & retrieves the daily transactions of an organisationSummary Points: Summary Points: Summary Points:§ must be organised before it can be stored & § tools for analysis may include: tables, queries & § buying goods at a Point of Sale terminalanalysed by the info. system. reports from a database or spreadsheet§ if not organised, data could be meaningless § people make decisions based on the information § processing eftpos / credit card transactions they receive from an information system§ may require sorting, summarising, classifying. § keeping track of the volume of steel produced at Bluescope Steel Example:Example: After doing a count of students from the school’s data- Example:Paper forms for new school enrolments have to match base, it was discovered there are 30 less students in Tracking one’s new computer system on the web fromthe database fields that the school uses. Yr.7 than Yr.8. Decisions have to be made as to how Dell computers which is assembled in Malaysia. large the Yr.7 class sizes will be (24 versus 30).IPT HSC Summaries Pg. 4 Patrician Brothers College 2010
  5. 5. Concept: Type of IS: Decision Support Systems Concept: Type of IS: Expert System Concept: Type of IS: Management Information Sys. (DSS)Definition: assists people to make decisions by provid Definition: provides information & solves problems Definition: provides information for an organisation’sing information, models and analysis tools. that would otherwise require a person experienced in managers. It presents basic facts about the perform- that field (an expert). ance of the organisation.Summary Points: Summary Points: Summary Points:§ used when an organisation has to react to some- § an expert systems asks a lot of questions and com § examples: reports on sales, stock inventory,thing unexpected (911, SARS epidemic) pares the answers to a knowledge base. payroll, orders & budgets.§ used when changes have to be made § useful in diagnosing, monitoring, selecting, § Executive Information System: designed for the designing, predicting and training. needs of senior managers & provide information on§ accuracy depends on mathematical model. strategic issues, using data from the share market,§ expert systems are a type of DSS § the solutions from an expert system are not always commodity prices, interest rates & other economic correct indicators.Example:A stockbroker uses software that analyses the stock- Example: Example:market & helps the user to make decisions about Helps doctors diagnose infectious blood diseases & China’s economic indicators indicate it has a demandbuying or selling shares. prescribes antibiotics. System uses medical history, to purchase more steel from Bluescope steel. Manage- symptoms & lab tests to make a recommendation. ment adjusts its planning accordingly.Concept: Type of IS: Office Automation Systems Concept: Database Management System DBMS Concept: Flat file databaseDefinition: provides people with effective ways to Definition: software package that builds, maintains, Definition: organises data into a single table.complete administrative tasks in an organisation. and provides access to a database. Summary Points: Summary Points: § data redundancy occurs when using more than 1Summary Points: § School database: MAZE db.§ software tools: word processing, spreadsheets, § School Library catalogue system: Alice § file: is a block of data. Divided into related recordsdatabases, desktop publishing, slide shows, project § Video Hire database § record: collection of facts about 1 specific entrymanagement § RTA database in a database. Divided into 1 or more related fields§ communication technologies: web browsers, email, § Accountant’s database § field: specific category in a database. Datafacsimile, paging, voice mail, mobile phones § Board of Studies database items are made up of characters. § restricts access if needed § character: the smallest unit of data people can use§ emails, forwarding phone calls, photocopying, § checks for data entry errors § keys: fields used to sort & retrieve informationprinting via network, uploading to internet, sending § shows db performance § single key: a field in which each item is uniquefaxes, paging Principal, radioing grounds people § allows changes of DB structure § composite key: or compound key made by joiningExample: Example: 2 or more fields together. eg. chrimeaipt04The administrative tasks carried out by the Office staff A DBMS adds records, delete records, creates database § primary key: a key that must have a value, it canat The Illawarra Grammar School. Same may be true design, links tables for relationships, produces reports, not be empty or null. It is unique.at parents place of work. does queries and only allows one person to access a § secondary key: a second field that contains useful record at a time. data, used for sorting. eg. Smith Anne, Smith BillIPT HSC Summaries Pg. 5 Patrician Brothers College 2010
  6. 6. Concept: Relational Databases Concept: Relational Databases - relationships Concept: Relational Databases – One to One RelationshipDefinition: organises data using a series of tables Definition: the way entities are related to each other Definition: this occurs when only one record in awhich are linked using relationships between fields. in a relational database. table relates only to one record in a second tableAttempts to keep data redundancy to a minimum. § A primary class has only one teacher and thatSummary Points: Summary Points: teacher is assigned onlyone class.§ schema: an organised plan of the entire database § Can be One-to-One § Only 1 customer can purchase a new car and theshowing how & where data is found, descriptions of sale of each new car is related to only onethe data & the data’s logical relationships. Usually, customerschema consists of several pages with many elements: § Can be One-to-Many NOTE: read the tables left to right AND right to left§ entity: a specific thing in a relational databaseabout which information is collected and stored.eg. school database would have an entity for students, § Can be Many-to-Manyteachers, classes, and students and classes§ attribute: a defined property of an entity in a re-lational database. eg: student entity would have:studentID, Firstname, Surname, Address, City, etc.Concept: Relational Databases – One to Many Concept: Relational Databases – Many to Many Concept: Relational DB: primary / foreign key Relationship RelationshipDefinition: when a single record in the first table Definition: a single record in the first table can be Definition: Primary Key is field that UNIQUELYcan be related to one or more records in the second related to one or more records in the second table, identifies that object within its table eg. StudentID.table, but a single record in the second table can be and a single record in the second table can be related Foreign Key is a field of a table that is a primary key ofrelated to only one record in the to one or more records in the first table another table. It is used to create a relationshipfirst table. § Each student studies many subjects, and each between a pair of tables.§ One student can take out many books from the subject is studied by many students Primary Foreign library, but any one book can be taken out by one § Must use a linking table for many-to-many Key Key student at a time. relationships in a relational database§ This the most common relationship that existsIPT HSC Summaries Pg. 6 Patrician Brothers College 2010
  7. 7. Concept: Relational DB – Linking Many-to-Many Concept: Relational DB: Tuple, Forms Concept: Relational DB: data modelling RelationshipDefinition: a linking table is inserted by copying the Definition: Tuple: a row in a table is called a tuple of Definition: the process of identifying entities, thePrimary key from each table an entity or one record. relationship between those entities & the attributes of Form: in a db used to view, enter and change data in a those entities. table. Summary Points: Summary Points: § used to develop a schema for the database § each tuple of an entity must be uniquely identified by a key 1 n 1 § is critical to creating an efficient database n § db forms can need to be well designed § tools used for data modelling: § data dictionaries § schematic diagrams Example: § normalisation Access database tables and forms used in past pract- ical examples.Concept: Data modelling: Data Dictionary Concept: Data modelling: schematic diagrams Concept: Data modelling: normalisationDefinition: a comprehensive description of each field(attribute) in a database. (field size, data type, name, Definition: graphical tools that help define the data Definition: the process of organising data into tablesfield description. base & develop a schema. so that the results of using the database clear andSummary Points: § entity-relationship diagram (ERD) is a graphical used as intended.§ Field name is the name of the field method of identifying entities & showing relationships Summary Points:§ Data type: the kind of data that can be stored in between them. § A refinement process that aims to reduce datain the field eg. text, memo, graphic, currency, date, § helps to decide what data is needed or excluded redundancylogical fields (Y/N) § complex data is separated into more tables.§ Field size: the number of characters allowed in § First Form Norm (1NF): moving data into separateeach field (up to 256 characters). A memo field allows tables of a similar type. Each table given a primary keyover 256 characters. § Domain/key normal form (DKNF): a key uniquely§ Description: specifies the contents of the field. identifies each row in a table. This is the final level of 1 n 1eg. Access’ data dictionary 1 n n normalisation that db designers aim to achieve.§ data dictionary consists of metadata which isinformation about data. It provides common ground if Example:several people are developing the same database. It Having a database that has a table for products, areduces data redundancy. table for customers and a table about each product§ calculated field: has a formula into which a and its price.calculation results eg. calc_field = price * unitsIPT HSC Summaries Pg. 7 Patrician Brothers College 2010
  8. 8. Concept: DB Storage & Retrieval: Sequential access Concept: DB Storage & Retrieval: distributed db Concept: DB Storage & Retrieval: storage media Direct accessDefinition: Sequential access occurs when data is Definition: is a database located at more than one Definition: online: storage device is directly under theaccessed in a sequence. Direct access occurs when site. It acts like a single collection of data but is users control. Offline: storage device is not directlydata is accessed without accessing previous data items geographically dispersed. under the users control. eg. centralised databaseSummary Points: Summary Points: Summary Points:§ sequential: like accessing a song on a music cas- § reduces the cost of transmission § hard disk: made of metal covered with magneticsette tape. To get to song 4, one has to fast forward material. Direct access. Measured in gigabytes usuallythrough the first 3 songs. Used in backup magnetic § optical disk: plastic disk. Data is read / written totape. § more difficult to obtain a complete view of the db disk using laser technology. CD, DVD§ direct: like accessing a song on a music CD. To § removable cartridge: hard disk encased in aget to song 4, one goes directly to it. cartridge and can be removed like a floppy disk. o an index may be used in a db. It is very like § needs to be synchronised with each other. eg. zip drive, jaz disk an index in a book. ‘Absolute referencing’ is on § a two-phase commit is used to maintain consist- § flash memory: data stored to flash memory eg. page 162 of the text book. ency usb thumb drive o indexing requires more processing Example: § magnetic tape: cheap, thin plastic ribbon inside a o records are rarely physically sorted in a db The RTA may use a distributed db system. cartridge. Sequential access. Used in backups of data bases.Concept: DB Storage & Retrieval: Encryption / Concept: DB Storage & Retrieval: Backup Concept: DB Storage & Retrieval: Security DecryptionDefinition: process of encoding data (encryption) and Definition: backup is another copy of the data that Definition: involves a series of safeguards to protectprocess of changing it back (decoding, decryption). can be used to rebuild the system. the data and the data’s physical storage media. Summary Points: use encryptionSummary Points: Summary Points: § close circuit TV on terminals§ most effective way of achieving data security § when the system goes down, the backup is used § allow restricted access to work station room viaduring transmission. in the recover procedure key lock, swipe card or biometrical device§ essential for transferring financial transactions § son, father, grandfather backup strategies § use level of password control. Administrator has§ used extensively on the Internet § inferential backup strategy: since last full backup control over the entire db. User is restricted parts of§ involves complex manipulations of bit patterns. only daily files changed or are new are backed up daily the db and can only read the data, can’t modify the§ asymmetric: requires a key for encryption & a key § differential backup strategy: since last full backup datafor decryption. Public key is used to encrypt, private weekly new or changed files are backed up daily § use a firewall if connected to the Internetkey is used to decrypt. (verifies & authenticates incoming data)§ symmetric: requires the same key for both § store backup tapes off siteencryption and decryption. eg Data Encryption Example: Example:Standard Student directories of TIGS are backed up everyday MAZE, school’s database. Bursar has full control, with a full backup done on Friday evenings. secretaries have partial control (can modify records), staff has access to student records only and can only read the records.IPT HSC Summaries Pg. 8 Patrician Brothers College 2010
  9. 9. Concept: DB Manipulations: Concept: DB Manipulations Concept: DB Manipulations Summary Points: Summary Points:Summary Points: § Relational operators: indicates relationship be- § sql contains key words such as§ sorting: the process of arranging data in a tween 2 expressions eg. Order ID = 15 SELECT, FROM, WHERE and ORDER BY particular order: descending or ascending § Logical operators: used to combine queries § must use correct syntax§ searching: the process of examining the database eg. AND OR NOT operators used. § QBE allow easy generation of SQLto retrieve selected data. Large db’s create a query. § wildcards: represent unknown characters. eg. ??§ query: is the search of a db for records that meet stands for two characters. * substitutes for anya certain condition eg. Classname = IPT number of characters§ query by example (QBE): in Access, a graphical § Lastname = Ma? may produce Mat or Mayuser interface is used for the user to match criteria § Lastname = Ma* : Madrid, Martinelli, Martin, Marsagainst a field.§ SQL: in Access, QBE produces SQL language inthe background. (structured query language)Example:Access database practical examples used in class.Concept: DB Displaying Concept: DB Report Design Concept: DB Issues: Data sourceDefinition: presenting the output from a db to meet Definition: Reports should be designed well. Definition: The source of the data is the person ora given purpose. A report is the formatted & organ- organisation that developed the dataised presentation of data. Summary Points:Summary Points: Summary Points: § ethical issue: goes against the moral code of§ Report generator quickly produces a professional § Headings should indicate purpose a society eg. copying music illegallylooking report. § Layout: tabular, column § social issue: has impact upon the individual and§ hardcopy or softcopy reports § use of text should be balanced with white space a significant number of people of a society. (locally§ report header § use of consistent styles regionally, & nationally). ATM’s displaced workers.§ page header § page numbers / dates should be included § informal source: conversation, meetings or§ details of body observation§ page footer § formal source: report, book, official document§ report footer § no guarantee to source’s accuracy § shouldn’t use other people’s work without per-Example: Example: mission (copyright)A report generated in Access by using the Report A report generated in Access by using the Report Example: text, images gained from the InternetWizard which includes all the above summary points Wizard which includes all the above summary points should at least be acknowledged in one’s work.IPT HSC Summaries Pg. 9 Patrician Brothers College 2010
  10. 10. Concept: DB: Accuracy of Data Concept: DB: Integrity of Data Concept: DB: PrivacyDefinition: is the extent to which data is free from Definition: describes the reliability of data. It is Definition: is the ability of an individual to controlerrors. Data validation techniques are used to check accurate, current & relevant personal data.data entry in a database form. Summary Points:Summary Points: Summary Points: § db’s allows client lists to be sold to marketeers§ range check: restricted to a range of values eg. § Need to cross reference when researching on the § users of a db system have different levels ofpostcode range > 500 and < 8500 Internet access depending on their username & password§ list check: compared to a list of acceptable data. § An URL may be accurate at first, but 3 months § db lists are for sale on the Interneteg. lookup table for the states in Australia. Entry is later, the URL may be a dead link, hence, not current § gov’t db’s allows for cross – referencing on individslower, but more accurate nor relevant. uals to try to stop fraudulent claims.§ type check: checks that the data type is correct. § data accuracy, data security & data integrity are § credit card numbers are encrypted & stored ineg. text is entered when a number is required in a db closely related to each other. databasesfield. § Australians may check their files and go through§ check digit: a digit calculated from the digits of a Example: procedures to correct errors in their filescode number A new David Jones customer may subscribe to their Example: catalogue. If customer moves & doesn’t notify DJ’s, Clerical staff have copied staff phone numbers & data has lost its integrity. addresses & sold them to Insurance sales people who in turn contacted staff on the list to make a sale.Concept: DB: Warehousing & Datamining Concept: DB: calculation of Storage Concept: DB: Emerging technologiesDefinition: data warehouse is a database that col- Total Field size of each field X number of records =lects information from different data sources. The number of bytesdata is analysised to assist in decision making.Data mining is a process that looks for relationships & Summary Points:patterns in the data store in the data warehouse. § smart card: accounts are debited from smartSummary Points: card; much personal details can be placed on it§ data mining discovered that the air conditioning ofcertain jet aircraft malfunctioned 2 or 3 weeks before § New database software and strategiesthat particular model crashed.Example:There may be a relationship between meat pie sales& tomato sauce sales.IPT HSC Summaries Pg. 10 Patrician Brothers College 2010
  11. 11. Concept: Concept: Concept:Definition: Definition: Definition:Summary Points: News Article: Y/N Summary Points: News Article: Y/N Summary Points: News Article: Y/N§ § §§ § §§ § §Example: Example: Example:Concept: Concept: Concept:Definition: Definition: Definition:Summary Points: News Article: Y/N Summary Points: News Article: Y/N Summary Points: News Article: Y/N§ § §§ § §§ § §Example: Example: Example:IPT HSC Summaries Pg. 11 Patrician Brothers College 2010
  12. 12. Polling token passed Hybr id CSMA/CD Car rier Sense Multiple Access & Collison Detection Network Inter face car d Server s OSI Reference Model Transmission of Data Routers/Switches Layer 7 appli cati on Network Administrator Protocols / handshaking Bri dges/Gateways Layer 6 pr esentati on Network Operati ng sy stem Networks Hubs Layer 5 session Protocols administr ation Network Topol og i es Transmission Medi a Layer 4 tr anspor t Handshaking fi le manag ement Network AccessMethods Wi reless tr ansmission Layer 3 netw kor Protocol Speed appl ications Layer 2 data link Err or Check ng i r esour ce manag ement Comms Setti ngs Characteri stics Communi cation securi ty Layer 1 physi cal Concepts Network Har dwar e Log on / Log off Data Source Traditional Transmitter Teleconfer encing Transmitting Messag ing : Transmission Network Softwar e Messag ing Systems Examples & Receiv ng i Telephone medium components Electr onic Commer ce Encoding / Decoding Call waiti ng Recei ver Intr anet Call blocking Destination Ex tranet anal og ue / di g ital conver sions Fax Attachments Paper messag e Soci al context Communi cation Cli ent-server ar chitectur e Mi si nterpretation Messag ing systems Systems Pag er Processing peer to peer Power r el ationshi ps Other data conver sions Pri vacy /Confidentiality Infor mation New Messag i ng E-j unk Mai l Issues Processes Voice Mail Infor mation Over load Displaying Telephone Email Emerg i ng Technolog ies EFTPOS ter minal SMS Web page Inter net Mobile Phone Computer M onitor Mob. Phone Televi si on Services: weather , Wor k ing from Home: Bandwidth news, airl ines Inter net Trading : Telecommuti ng Hack ing softwar e Taxati on Vir tual Or g ani sation 3G mobile phones Coll ecti ng ATM termi nals Employment ri pples LAN withi n homes EFTPOS ter minals Nature of busi ness LG Refr idg erator Telephones - voice mail Trade bar ier s Inter net v a power cables i keyboar ds - email Censor ship Ty anny of Distance r video cameras Inter net Banking New video / audi o codecs bar code scanner Radio & Vi deo New sear ch eng ines ICQ , FTP Lar g er data pi pes Neti quette dig ital TV spam WAP Less Isolation in Country Thin Cl ients Wi reless laptop securi ty Conv erg ence Bluetooth wir eless Wi reless laptops, bui lding sIPT HSC Summaries Pg. 12 Patrician Brothers College 2010
  13. 13. Concept: Communication System Concept: Protocols Concept: HandshakingDefinition: enables people to send & receive data Definition: In data transmission, a set of rules that Definition: the sending of signals to reach an agree-and information governs the transfer of data between computer ment about which protocol to use to accomplish devices. an exchange of information.Summary Points: Summary Points: Summary Points:§ data source: produces the data to be sent § computers must use the same protocols or data § in a modem, those crunching sounds is hand-§ transmitter: encodes the data into a signal suitable transfer will be unsuccessful shaking in progressfor a transmission medium § when 2 devices successfully handshake, a con-§ transmission medium: is a channel, such as a § a German and a French person may agree to nection is madecable, in which the signal is transmitted to the dest- speak English so that communication can take place § hardware flow control: uses a dedicated connect-ination. Signal may be distorted or changed during ion, such as a wire, to control the flow of datatransmission. § protocols have been written to International § software flow control: uses a special code sent§ receiver: decodes the signal back into the original standards with the data to control the flow of data: XON/X0ffdata or an approximation of the data.§ destination: is the receiver of the information Example: Example:Example: The computers at TIGS communicates with the file- When the printer buffer is full, the printer sends aFM commercial radio stations. eg. Wave FM server using the Ethernet protocol. XOFF to pause print data until the buffer http: means hypertext transfer protocol (web pages) empties.Concept: Speed of Transmission Concept: Error Checking Concept: Communication SettingsDefinition: the speed of data transmission is deter- Definition: When data arrives at its destination, itmined by the transmitting device & bandwidth. may contain errors. Definition: parameter settings that may be altered to Summary Points: allow computer or peripherals to communicate.Summary Points: § parity check: can be odd or even. Addition of§ bandwidth: the capacity of the transmission binary numbers agreed to be odd or even. 2 errors Summary Points:ium. eg. fibre-optic cancels each other out indicating correct transmission § bits per second: speed of transmission: 56,000 § checksum: 0’s & 2’s in a block summed. Checksum § data bits: the number of bits in each group of§ bits per second: is the maximum number of bits is sent to receiver. Receiver carries out checksum. If data which is a 7-bit ASCII or 8-bit ASCIIthat can be transmitted in 1 second. bps aka bit rate agreed, OK sent. If not block resent. Errors can also § parity: indicates if data has parity for error de-§ baud rate: maximum number of electrical cycles cancel each other out. tection. odd, even or Nonethat can be transmitted in one second. § CRC: binary numbers in the block are treated as 1 § stop/start bits: parameter is used to identify each long binary number & divided by a number (CRC-32). byte. (start of a byte, end of a byte).Example: The remainder of the division is retained & sent. § flow control: handshaking protocol such as XON/56,000 bits may be forced through a baud rate of Receiving computer does the calculation. If both agree XOFF4,800. OK is sent, if not block is re-sent. Example: § Error correction: most common, simplest is to send Computers communicate with printers using these a code back to retransmit the last data block. settings as well as to other computers.IPT HSC Summaries Pg. 13 Patrician Brothers College 2010
  14. 14. Concept: Teleconferencing Concept: Messaging System Concept: Electronic EmailDefinition: the use of electronic transmission to allow Definition: used to send messages to people in dif- Definition: mail sent electronically. Has been arounda meeting to occur at the same time in different places ferent locations who can receive the message at a long before the Internet came into being. later time.Summary Points: Summary Points: Summary Points:§ audio conference: a single phone call involving § Traditional: include the telephone & fax. § email address: consists of 2 parts3 or more people at different locations. § cc: carbon copy. Everyone can see to whom it § telephone answering system was sent§ video conference: allows people in different places § Fax: sends graphics over telephone lines. § bcc: blind carbon copy. Sent to other people butto see video images & audio of each other. § computers may have a fax modem they can not see who else it was sent to. § subject: topic of the message. Beware of general§ teleconferencing reduces costs (airfares, hotels § voice mail: storing & forwarding spoken messages topics, could have a virus.meals) by simulating a face-to-face meeting. stored digitally . § reply: automatically inserts return email address § address book: contains people’s email addressesExample: Example: § mailing list: a group of people who may want toBluescope Steel management video conferences with Typical small business will have a telephone, answer- receive the same messages.a branch in another country eg. China ing machine and fax. Mobile phones offer voice mail. § signature: several lines that can be appended to Middle management TIGS staff have voice mail. emails automatically.Concept: Electronic mail continued: Concept: Electronic Commerce Concept: Parallel/Serial TransmissionIssues: Definition: is the buying and selling of good and Definition: Parallel: transmission of data at the§ spam services through the Internet. same time using separate channels. Serial: transmis-§ anti-spam legislation to prevent spam sion of data one after the other§ anti-spam software, filters in email software Summary Points: Summary Points:§ society impact: an additional activity (checking § provides 24 hour availability, global reach § Parallel: like a multilane highway. 8 bits arrive atemail) for 10 – 20 minutes daily close to a set time. § security of credit card numbers are an issue the same time. Is faster but easily gets out of syncro-§ organizations (TIGS) use to to communicate § amazon.com, www.ebay.com most famous at the nisation. Limited cable length: 3 metresinternally. moment for web orders § Serial: like a single lane highway, 8 bits arrive§ beware of creating emotional replies § has gone through a bust cycle. one after the other.§ deleted emails can be recovered by an employer § EFTPOS connects from retailer to bank Slower, but easy to 0 1and used against an employee if sent on employers § Internet Banking: people transfer funds between detect errors and 0email system accounts at home, bank employees lost jobs, banks correct. 0§ spread of viruses. Plain text is the only safe closed 1 1method. HTML can have hidden virus coding. Don’t Example: 0open attachments without scanning for viruses. www.wineplanet.com.au was a famous site in Austral- 1§ reduces the tyranny of distance world wide ia for selling wines. Wholesalers refused to sell to§ spread of Internet cafes them at a fair price. Eventually the company was pur- 01001101 chased & the site no longer exists.IPT HSC Summaries Pg. 14 Patrician Brothers College 2010
  15. 15. Concept: Asynchronous / Synchronous transmission Concept: simplex, half-duplex, full-duplex data flow Concept: Some common data Transfer Protocols: § x.25: standard packet switching protocol. UsedDefinition: Asynchronous: sending of data by identi- Definition: for low speed applications, such as credit card veri-fying each byte with special start & stop bits. Simplex: 1 direction: eg. TV transmission fication & automatic teller machine transactions.Synchronous: requires all data to be sent at the same § TCP/IP: transmission control protocol/ Internettime. protocol. Common set of rules for data transmission & Half-duplex: both directions but only 1 way at a time. error detection across the Internet. It works by break- eg. Citizen’s Band radio (CB radio). ing information into smaller packets of data. § HTTP: hypertext transfer protocol. Allows access or web pages that are based on hypertext. Enables user to send & receive files over the Internet Full-duplex: both directions at the same time. eg. § FTP: file transfer protocol. Enables user to login to telephone conversation a server. Oldest form of remote file access for the Internet. § POP: post office protocol. Specifies how email messages may be exchanged between a computer an ISPConcept: Data Transfer Protocols continued: Concept: Network Concept: Topology is the physical arrangement of the devices in a network.§ MIME: multipurpose Internet Mail. designed to Definition: is a number of computers & their periph-enable files to be sent across the Internet as email. eral devices connected together in some way. Definition: Bus: all the devices are attached to a§ XModem: file transfer protocol developed in the direct line called the bus.late 70’s for PC’s. Data is transferred in blocks 128 Summary Points: Summary Points:bytes long. Later versions supported CRC. § node: each device in a network § nodes listen if the network§ YModem: an extension of XModem. Blocks in- § terminal: devices that send & receive data from is clear. If so, a node willcreased to 1024 bytes long. Increased reliability of another computer system. transmit.error checking & increased data transfer. § PC’s classified as intelligent terminals since pro- § If collision occurs,§ ZModem: rectified limitations of YModem. Uses a cessing can be done at the terminal. CSMA/CD Carrier Sensevariable block size, supports CRC, provides for high § Local Area Network: LAN. Covers a small geo- Multiple Access andspeed packet & network communication environments. graphical area. Collision Detection allows § WAN: can used normal phone line, leased data node to re-transmit at lines. (Wide Area Network) later time. § packet switching: a technique that divides mes- § Ethernet Protocol is base sages into small data packets, transmits the packets, on a bus topology. and later re-assembles the packets to form the orig- inal message. Packets do NOT have to take the same route to destination.IPT HSC Summaries Pg. 15 Patrician Brothers College 2010
  16. 16. Concept: Topology: Star Concept: Topology: Ring Concept: ServerDefinition: has a central computer with each device Definition: all devices are attached so that the path Definition: is a computer that provides services toconnected directly to it. is the shape of a continuous circle. other computers on the network.Summary Points: Summary Points: Summary Points:§ central computer § each device as a unique address § file server: stores the programs & data shared by receives messages § data flows in one users. Files can be retrieved by any node if it has & sends them to direction, moving access rights. the destination. from device to § print server: controls 1 or more printers & stores§ No data collisions device until it arrives data to be printed (print queue). with this method at destination § mail server: provides email facilities. Stores in-§ if central computer § This avoids data coming mail for distribution & forwards outgoing mail. fails, entire system collisions § web server: provides a connection to the Internet. goes down. § A node transmits Stores web pages that are accessed by others via the§ allocates a certain when it receives a Internet through their browsers. eg. IPT web site. amount of CPU time for each user token, hence, token ring networkConcept: Data Traveling between networks Concept: Network Access Diagram Concept: Web server with Order Form (Worth memorising). (Worth memorising)Summary Points:§ router: determines where to send a data packetbetween networks. It determines the best route for agiven data packet.§ switch: directs data packets along a path within a Internet Web & MerchantLAN. Is a simpler device than a router. High speeds. ServerLimits traffic to the intended node rather than being Financialbroadcast over the entire network as a hub does Network§ hub: a central connecting device to nodes.Centralises cable connections. Smart hubs existtoday. Used in slower connections (10Mb/sec.) Catalog§ bridge: links two similar networks. and Order Database§ gateway: links two dissimilar networks. Buyer with BrowserIPT HSC Summaries Pg. 16 Patrician Brothers College 2010
  17. 17. Concept: Credit Card Payment Solution Networks Concept: Transmission Media Concept: Transmission Media continued: Summary Points: Definition: data is transferred along a transmission § twisted pair: consists of copper wires twisted to medium form a spiral. Twisting reduces the amount of inter- Summary Points: ference from other cabling. Cat 5, 6 cabling are twisted in a special manner to allow 100 kbps. It is Encrypted Payment authorisation the slowest medium request and • RJ-45 Connector § coax: like the cable running from one’s VCR to the Unshielded Twisted Pair response back of the TV. Has shielding to allow for little elect- Private AS2805 secure network rical distortion. Used over a few kilometres. Haven’t seen it used in recent times.End User • BNC connector Coaxial Cable § fibre-optic: uses laser light to carry data. It is Credit free from electromagnetic & radio interference. Can Card transmit at high speeds & is secure. Processor Example: cat 5 is blue cabling at back of computer. eSec Westpac bank Application Web • ST fibre-optic connector TIGs uses a combination of Cat 5 cabling and fibre- Server optics to send data to the various buildings. No coax is used.Concept: Network transmissions Concept: Network Operating System Concept: Intranet§ baseband: uses the entire capacity of copper cabl-ing to transmit one signal at a time. Definition: is an operating system designed to sup- Definition: is a private network that uses a similar§ broadband: divide the cable so that several signals port computers connected on a LAN. It contains the interface to the Web.can be transmitted at the same time. eg. ADSL sends rules for communication & determines how to send & Summary Points:the phone signal & internet signal through 1 phone receive data. § main purpose is to share information, resourcesline Summary Points: among employees of an organisation. eg. industrial§ wireless: moves data through air & space. § NOS tasks: administration-> manages users, file- technology at TIGS-> can be seen at school but not§ microwave: high-frequency radio signal sent management eg. home directories, applications-> through the Internet.through space in a straight line from 1 antenna to handles requests to share applications & data, reroutes § usually has links to the Internet (seamless)another. Weather can affect transmission rates. to specific printer, resource management, security § users sometimes can’t tell if they are using an§ satellite: specialised receiver & transmitter placed § network administrator: person who manages the intranet or the Internetin orbit. A signal is sent from the ground to the sat- network: grants access rights to users & various dir- § Extranet: is an intranet that is accessible toelite & back to ground. eg. TV signals from Europe to ectories, network security, installing new software, customers, suppliers or others outside the ogranisationAustralia. updating software, monitoring daily activity, enforcing Example:§ Wireless LANs: use radio waves not cables for the licensing agreements, developing a storage system, TIGS has access to the intranet run by the companyLAN medium. Becoming very popular but there are carrying out backups. that carries out most of the networking support. TIGSsecurity concerns. § login / password procedures: usernames have is able to check on the status of a particular works§ mobile phones: transmit data to a grid of cellular different levels of access in the network. eg. comput- order that TIGS has given them. If it isn’t in thestations that are linked to wire-transmission telephone ing teachers can read students files in their home system, then the order isn’t being carried out. (Savesnetwork. directories but can’t write to them. phone calls).IPT HSC Summaries Pg. 17 Patrician Brothers College 2010