August 1999
SD206 : SYSTEMS DESIGN

QUESTION 2

Total Marks: 20 Marks

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(a) List two important criteria which must be taken into account when determining a design for improving system performance. [2]
  • Does it help to resolve the problems of the existing system?
  • Will the new design move the organisation nearer towards its business goals?
  • Is the change desirable from the user's point of view?

 
(b) Illustrate, using data flow diagrams, the following steps in deriving a logical model of a new system;

(i) Resequence the activities to improve productivity.

(ii) Reduce data redundancy to achieve higher data integrity.

(iii) Introduce new controls to enhance the flow of the system.

(iv) Simplify the process to reduce the turnover processing time.

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Any suitable solutions accepted.
(c) (i) List two characteristics of real-time systems.

(ii) What are the differences between soft and hard real-time processes?

(iii) Give two examples of applications which are suited to batch processing, rather than real-time processing.

 [2]

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(i)
  • Process orientation.
  • Online file avalibility
  • Very short time interval.
  • Constant updating.
  • Organisation of records for rapid access.

(ii) A hard real-time process are those in which the application fails completely if the process does not always meet the time constraints, whereas a soft real-time process are those in which the system's performance becomes degraded if the time constraints are not always met.

(iii)

  • General ledger applications.
  • Payroll applications.
  • Accounts applications.