Unit 5
Systems Development


Consider existing system:-

Fact finding:-

Data dictionary





Throwaway prototyping - prototype is discarded before the real system is started

Evolutionary prototyping - prototype developed into a working system

Systems flowchart - diagram showing an overview of a complete system (pictorial representation of how the system will work)

User interface:-

Development - coding and testing of the programs which make up the system and the testing of the system as a whole

Testing strategies:-


Methods of conversion:-

Software testing:-

Alpha (acceptance) testing - testing continues until an agreement is reached between the developer and the system purchaser that the system works correctly and fulfils all the system requirements

Beta testing - involves giving the package to a number of potential users who agree to use the system and report any problems to the developers -> detects errors that may not have been anticipated by the developers

Post implementation review

Software maintenance:-

Laws of software maintenance:-

  1. A program used in the real-world environment must change or become less useful over time
  2. As programs evolve, the structure becomes more complex. Extra resources should be devoted to simplifying the structure
  3. Program evolution is a self-regulating process. The number of changes which may be implemented at any one time is limited.
  4. Rate of program development is approximately constant for the life of a program (and is independent of the resources devoted to system development)
  5. The incremental change in each release of a system is approximately constant

Factors affecting maintainability:

Installation manual:-

Operations manual - used by anyone concerned with the day-to-day operation of the computer system

User manual - aimed at various levels of end-user (senior managers, middle managers, clerical workers) who will be using the system


e.g. clerical worker may need to know how to enter daily or weekly sales figures; sales staff may need to know how to enter customer details and put through a sale; managers need to be able to extract information for decision-making

Methods of training:-