Aug 1998 SW204: Software And Files Design (Question 1) Suggested Solutions

1.	(a) List two operating system structures.		[2]
	One mark should be awarded for each valid point. Monolithic Client-server
	(b)	(i) Define the term multiprogramming.	[1]
		Multiprogramming involves several programs being in memory at the same time. Other sensible answers should also receive credit.
		(ii) List two benefits of multiprogramming.	[2]
		One mark should be awarded for each valid point (up to a maximum of two marks). Examples include the following: CPU utilisation is increased. Throughput is increased. System performance is improved. Other sensible answers should also receive credit.
	(c) Define the term compaction.		[2]
	Compaction is the process of moving all occupied memory to one end of storage (1 mark), leaving all unused contiguous storage space at the other end (1 mark). Other sensible answers should also receive credit.
	(d) Define the term marco expansion.		[2]
	An assembler decodes and updates the mnemonic of a macro instruction (1 mark); the macro instruction is expanded by the insertion of corresponding instructions into the machine language program which is being generated (1 mark). Other sensible answers should also receive credit.
	(e) Distinguish between system software and application software.		[2]
	System software is concerned with software that assists in the execution or development of programs (1 mark), whereas application software is concerned with programs that are developed to meet the specific needs of an end user (1 mark). Other sensible answers should also receive credit.
	(f) Give two advantages of using a breadth-first search.		[2]
	One mark should be awarded for each valid point (up to a maximum of two marks). Examples include the following: The search will not get trapped exploring a blind alley. Each level is explored before a new level is generated. It is exhaustive: if there is a solution, then it will be found. Other sensible answers should also receive credit.
	(g) COCOMO is an example of an expert system.
		(i) Describe its domain.	[1]
		COCOMO’s domain is scheduling and staffing of software development projects.
		(ii) Describe its basic task.	[1]
		COCOMO helps engineers and managers to schedule and plan for software development projects.
		(iii) List two benefits of using it.	[2]
		One mark should be awarded for each valid point (up to a maximum of two marks). Examples include the following: It optimises the distribution of man-power in a large software project. It produces schedule reports with resource allocation. It helps new project managers to estimate and plan. Other sensible answers should also receive credit.
	(h) Give three disadvantages associated with compile-and-go loaders.		[3]
	One mark should be awarded for each valid point (up to a maximum of three marks). Examples include the following: The portion of memory occupied by the translator is wasted. The program must be translated each time it is run. It is difficult to handle multiple subroutines. It is difficult to produce orderly modular programs. Other sensible answers should also receive credit.