April 1999
SD206: SYSTEMS DESIGN

QUESTION 2

Total Marks: 20 Marks

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GRADE A
Sample student's solutions are indicated in green.
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(a) (i) What is the main role of a systems analyst? [2]
(ii) In addition to those required for analysis, what skills are essential for a systems analyst in the design phrase? [2]
(i) The main role of a system analyst is to study the current system, the new system requirement and offer a solution.

(ii) The systems analyst should have an analytical mind when studying the current system. Picking out the shortcoming of the system according to the new requirement. He should also be able to find out those requirement that are not explicitly stated.

 
(b) (i) List three of the main aspects of structured design. [3]
(ii) Draw a small example of how a system may be modelled in terms of a data flow diagram using the four basic symbols associated with structured design. [5]
(i) 3 main aspects of structured design are:
  1. Structured design uses the definition of the problem to guide the definition of the solution.
  2. Structured design seeks to conquer the complexity of large system by means of partioning the system into "block boxes" and organising them into hierarchies suitable for computer implementation.
  3. Structured design offers a set of strategies for developing a design solution from a well-defined statement of the problem.

 
(c) (i) What sort of information might be indicated by a diagram of a logical model of a system which has been marked up? [2]
(ii) List two sorts of tradeoff which might have to be dealt with in building a physical model. [2]
(i) The diagram of a logical model of a system will show what process is involved in the system and what data is moving between processes.

(ii) The 2 sorts of trade off are:

  1. The amount of process which is to stay manual or computerised.
  2. The amount of information to store as soft copy or hard copy.

 
(d) (i) Define the terms hard real-time processing and soft real-time processing. [2]
(ii) Describe the storage and access of records in a real-time system. [2]
(i) Hard real-time processing is when a system will fail if the time constraint is not met.
Soft real-time processing is when a system will give a degraded service when the time constraint is not met and still able to meet the user's requirement.

(ii) The storage of records is a real-time system is organised in a direct access mode for rapid access. Only the records needed for processing is retrieve and not the whole file/database.