Monday, March 28, 2011

Short, brief note...

System analysis and design

  • a six-phase problem-solving procedure for examining and improving an information system
  • make up the systems life cycle


http://www.google.com.my/imglandingq=system+life+cycle&hl=en&sa=X&tbm=isch&tbnid=9e2wkzFCjuH73M:&imgrefurl=http://www.computing2008.com/dvd:analysis&imgurl=http://www.computing2008.com/computing2008/_media/dvd:141a.jpg%253Fw%253D%2526h%253D%2526cache%253Dcache&ei=nZKQTdeKJIq4vgO0kpCoDQ&zoom=1&w=252&h=247&iact=hc&oei=kJKQTau6JdC9ceXF9ZYK&page=3&tbnh=135&tbnw=138&start=37&ndsp=19&ved=1t:429,r:0,s:37&biw=1366&bih=624


Phase 1 : Preliminary investigation

  • determine the need for a new information system
  • concerned with three tasks : define the problem, suggest alternative solutions and prepare a short report
  • accomplish by interviewing and making observations
  • if information system is large, the survey is done by systems analyst
  • if information system is small, the survey can done by end user
  • report may include schedules for further development of the project and presented to higher management

Phase 2 : Systems analysis

  • data is collected about the present system
  • new requirements are determined for a new system
  • concerned with gathering and analyzing data
  • completed by documenting the analysis in report
  • organization chart : shows levels of management and formal lines of authority
  • systems analysis report : describes the current information system, the requirements for a new system,and a possible development schedule



http://www.google.com.my/imglandingq=system+design+in+system+life+cycle&hl=en&biw=1366&bih=624&tbm=isch&tbnid=zdd8ixYJ5hBvM:&imgrefurl=http://www.cs.uct.ac.za/mit_notes_devel/SE/Jul2006/html/ch02s04.html&imgurl=http://www.cs.uct.ac.za/mit_notes_devel/SE/Jul2006/html/images/02_005.png&ei=156QTYe4D467ce-drJIK&zoom=1&w=736&h=409


Phase 3 : Systems design 

  • consists of three tasks : design alternative systems, select the best system and write a systems design report
  • evaluate the alternative system for economic,technical and operational feasibility
  • system design report is prepared for higher management and describes the alternative designs
Phase 4 : Systems development

  • has three steps : acquiring software, acquiring hardware and testing the new system
  • application software can be purchased as off-the-shelf packaged software and possibly modified, or it can be custom designed
  • suggests that an electronic mailbox be installed for maintaining security
  • the processed information is evaluated to see whether results are correct

Phase 5 : Systems implementation

  • another name is conversion
  • process of changing from old system to the new one and training people to use the new system
  • four approaches to conversion : direct, parallel, pilot and phased
  • direct approach : abandon the old, very risky, not recommended
  • parallel approach : run old and new side by side, very low risky, however very expensive, not generally recommended
  • pilot approach : convert part of organization first, less expensive but riskier than parallel conversion, recommended for situations with many people performing similar operations
  • phased approach : implement gradually, less risky but more expensive than parallel conversion, recommended for situations with many people performing different operations


Phase 6 : Systems maintenance

  • ongoing activity
  • spend more time and money on this phase 
  • has two parts : a systems audit and a periodic evaluation
  • in systems audit, the system's performance is compared to original design specifications 
  • to determine whether the new procedures are actually furthering productivity
  • all systems are evaluated from time to time to determine whether they are meeting goals
Reference :
computing essentials 2011

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