August 1999
SE203 : SOFTWARE ENGINEERING

QUESTION 4

Total Marks: 20 Marks

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(a) Describe what is meant by the following terms : transaction analysis, and transform analysis. [4]
Transaction analysis : a set of design steps allowing a DFD with transaction flow characteristics to be mapped into a predefined template for program structure.

Transform analysis : a set of design steps that allows a DFD with transform flow characteristics to be mapped into a predefined template for program structure.

 
(b) Jackson Structured Programming makes use of three basic constructs. Identify these three constructs, and draw their notation. In addition, write down some simple code to illustrate how each notation can be used. You may make use of procedural language, or simple pseudo-code to illustrate the use of each notation. Ensure that the relationship between your code and the construct is clearly demonstrated in the diagram. [7]
The three basic constructs are : selection, iteration, and sequential.

pic3.gif (8162 bytes)

main( )
{
A( ) ; /* Run subroutine A first */
B( ) ; /* Run subroutine B next */
C( ) ; /* Run subroutine C last */
}
A( )
{
D( ) ; /* Run subroutines D and E in this order */
E( ) ;
}
B( )
{
While-Do Loop /* Based on condition c1*/
}
C( )
{
If condition=true, G( ); /* Based on condition c2 */
Else H( );
}

 
(c) Jackson's notation allows for a hierarchical structure of a system to be represented. Consider the following scenario :

A computer system comprises of three main components, namely the Central Processing Unit, the Main Memory unit, and I/O units. The Central Processing Unit typically comprises a control unit, arithmetic logic unit, and a number of registers of two types : general purpose registers; and control and status registers. The Main Memory component can typically be organized into a number of memory words.

Making use of Jackson's notation, draw the structure for such a computer system.

 

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