Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Information Systems Gavin Crosthwaite 3 hours = 180 minutes 200 marks 10 short answer 8 extended answer Various topics Information Systems Databases Computer Architecture Information Systems Datum/Data raw unprocessed not useful/lacks meaning Information transformed processed useful Data Information Knowledge System Information Systems set of related components that process input data into output data that is organised, meaningful and useful Communication System set of related components that allows a data transmission, for instance a communication system in a computer allows it to transfer data to other computer An information system deals with data process, whereas a communication system is a system that controls the transmission of data Computer systems Computer systems that are Computer based information Information systems that are not information systems systems not computer based Information systems Management information system generates timely, accurate information helps make decisions Evolve from TPS Transaction Processing Systems captures and processes data from day to day activities batch processing collect over time & process all transactions later most today are online Computer Based Systems any information system which involves a computer Carriers companies that offer telecommunications between 2 points across the world Telstra iinet Service Providers Provides a service to customers but doesn’t own the infrastructure AAPT westnet System Development Life Cycle (SDLC) 1. Preliminary Investigation Feasibility Study technical legal operational Measure of how suitable system development will be to the company economical security Operational how well does it work? will they like it? will it meet user requirements? Schedule deadlines for project is it reasonable? Technical Hardware? software? people? Economic are the costs worth the benefits? Tools? ROI (return on investment)? cost/benefit analysis? Legal Issues such as govt. regulations? community concerns? 2. Analysis data gathering techniques? Observation? Interview? Survey? Questionnaire? context diagrams data flow diagram (DFD) packaged vs. custom software? convey all solutions? Select one find errors early 3. Design identify technical specs Hardware? Software? ERD (Entity Relationship Diagram)? Prototyping Establish an outline specification Develop a prototype Evaluate Specify Design and implement system mock up of final design user feedback outputs from system GUI (graphic user interface) CASE tools designed to assist in one or more activities in SDLC Data dictionary 4. Development write programs test modules Unit Test Systems test Verifies each individual program works by itself Verifies all programs in application work together Integration Test Acceptance Test Verifies application works with other applications Verifies the new system works with actual data finalise program 5. Implementation test the system in real life Documentation? help manual? train users? conversion of files to new system? pilot direct parallel phased Pilot start with small group of users and gradually add more users Phased – implement the new system in phases Parallel – use both systems simultaneously Direct – out with the old and in with the new Maintenance Represents 66% of the cost of the project perfective implies that while it runs smoothly there is still room for improvement adaptive all systems will need to adapt to changing needs within a company corrective problems frequently come up after a period of time, no matter how thoroughly it has been tested help desk? Context Diagrams boundary system? external entity? data flow? Data Flow Diagram Entities? Files? Vectors? Processes? ENTITIES square outside boundary system must go through a process FILE open ended rectangle what documents are we storing must go through a process VECTOR what information is moving? be specific!! PROCESS MUST be numbered!! MUST begin with a verb!! Information MUST be processed or changed!! Top-Down general design & moves to a more detailed design Bottom-Up Individual parts are specified in great detail first & then linked to form bigger system Closed Systems no matter transferred across system boundary limited to authorised use early Mac computers can’t modify its operations (ATM) Open Systems data moves across boundaries can modify operations PC as an example unauthorised exchange of information allowed internet Centralised Systems information is processed in one location all processing, software & hardware in one location as well Distributed Systems data processed without necessarily being connected to a central computer although distributed, information is transferred to a central computer Project Management Time management Gantt chart progress reports? team planning? work assignment? Databases DBMS (Database Management Systems) programs that allow a user to create a computerised database Definition collection of data organised in a manner that allows access for retrieval, and use of that data What are the qualities of valuable information? Accurate Verifiable Timely Organized Accessible Useful Cost-effective Types Flat File Single table spreadsheet like lots of repeating data Incorrect spelling of data Relational Database series of tables called relations joined by keys most commonly used queries used to retrieve data entered relation a set of tuples that have the same attributes a table atomic single entry per cell tuple represents an object or information about that object a row attribute single piece of data shown in a column used by developers to refer to a field how does it fit together little scope for query optimisation Index improves speed of queries in a database Random use labels or indexes to get to correct record eg: if name is Jefferson, go to J, then Je in the phone book first rather than each name in the book beginning with ‘A’ Sequential look at every record in order very inefficient humans wouldn’t do it, but computers have to be told use random first, then sequential Data Dictionary An element that contains data about each file in a database and each field in the database Keys Primary attribute in a database that uniquely identifies each tuple in a file Foreign a key from another table that is used to define a relationship to another record in another table has the same name and properties as the primary key from which it is copied Normalisation st 1 Normal Form (1NF) There are no repeating groups All the key attributes are defined All attributes are dependent on the primary key nd 2 Normal Form (2NF) st Its in 1 Normal Form It includes no partial dependencies (where an attribute is dependent on only part of a primary key) rd 3 Normal Form (3NF) nd Its in 2 normal form It has no transitive dependencies (where a nonkey attribute is dependent on another non-key attribute) Entity Relationship (ER) Diagram Entity Relationship SQL Queries Know how to create them!! Computer Architecture Central Processing Unit (CPU) control unit registers arithmetic logic unit (ALU) Buses Peripheral Component Interconnect (PCI) A standard describing how the peripheral components of a computer system may be connected together Universal Serial Bus (USB) a protocol for transferring data to and from digital devices NuBus interface used in Macintosh computers to transfer video data from memory to the graphics display card Small Computer System Interface (SCSI) interface that serves as an expansion bus that can be used to connect hard disk drives, tape drives, and other hardware components Random Access Memory (RAM) memory that allows any storage location to be accessed randomly Read Only Memory (ROM) memory whose contents can be accessed and read but cannot be changed Cache block of high speed memory where data is copied when it is retrieved from the RAM located on CPU level 2 Also located on CPU level 3 Reduced Instruction Set Computing (RISC) small number of assembly instructions each of which performs simple operations Complex Instruction Set Computing (CISC) large number of often complex assembly instructions more than one complex Fetch-Execute Cycle 1) Fetch 2) Decode 3) Execute 4) Store What is a fetch-execute/machine cycle? Four operations of the CPU comprise a machine cycle Step 1. Fetch Obtain program instruction or data item from memory Memory Step 2. Decode Step 4. Store Translate instruction into commands Write result to memory Processor ALU Step 3. Execute Carry out command Control Unit Storage Hard Drive? Compact Disc (CD)? Digital Versatile Disc (DVD)? Flash Drive (USB)? Open System Design Standards Compliance Firmware instructions and data programmed into the circuits responsible for controlling the operation of peripheral devices Software system software operating systems application software office suites Sequential Processing all processing on a single processor computer Parallel Processing to process data more quickly, more processors can be added to the system Distributed Processing Troubleshooting Preventative Maintenance 1) Defragmentation 2) Clear temporary files 3) Back up Full back up all files are saved time consuming Differential back up requires minimal space long recovery time Incremental back up Only recent changes saved even longer recovery time