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(a) (i) How do internal receivers differ
from external receivers? [2]
(ii) List two ways in which output may serve external receivers. [2]
(a) (i) Internal receivers belong to the
organisation – they are part of the
system – (1 mark) whereas external receivers are not part of
the
system (1 mark).
Other correct answers should also receive credit. [2 marks]
(ii) One mark should be awarded for each correct answer. Examples
include the following:
- To inform the receivers.
- To stamp an action.
- To help the receivers make decisions. [2 marks]
(b) (i) Describe two reasons why an
effective design should control the quantity
of data for input. [2]
(ii) Describe two ways in which the possibility of errors during the
input
process may be reduced. [2]
(b) (i) One mark should be awarded for each
correct answer. Examples
include the following:
- Data preparation and data entry operation depend on people;
reducing input requirements can reduce labour expense.
- Input can be slow; reducing input requirements can speed up
the entire process. [2 marks]
(ii) One mark should be awarded for each correct answer. Examples
include the following:
- Reduce the amount of data that has to be entered.
- Improve the input design. [2 marks]
(c) List two hidden costs of paper forms.
[2]
(c) One mark should be awarded for each correct
answer. Examples include the following:
- Costs of running out.
- Costs of using the wrong form.
- Costs caused by data float. [2 marks]
(d) (i) Define the term classification
code. [2]
(ii) Define the term mnemonic code. [1]
(iii) How does mnemonic coding reduce the likelihood of input errors?
[1]
(iv) Why might a company employ cipher coding? [1]
(d) (i) Classification codes place separate
entities into distinct groups,
called classes (1 mark). A code is used to separate one class from
another (1 mark).
Other correct answers should also receive credit. [2 marks]
(ii) Mnemonic codes use abbreviations to represent an object in a
visual means.
Other correct answers should also receive credit. [1 mark]
(iii) Mnemonic coding reduces the likelihood of input errors by
simplifying the input process.
Other correct answers should also receive credit. [1 mark]
(iv) Any appropriate example, such as “a company may not want
information in a personnel file to be accessed by data entry staff”
should be awarded a mark. [1 mark]
(e) Describe three approaches to reliability.
[6]
(e) For each of the following, one mark should
be awarded for naming the
approach and a further mark should be awarded for a satisfactory
elaboration:
- Error avoidance (1 mark). Here, developers and programmers make
every attempt to prevent errors from occurring at all (1 mark).
- Error detection and correction (1 mark). Here, design features that
detect errors and make necessary changes to prevent failures are
employed (1 mark).
- Error tolerance (1 mark). Here, strategies to keep the system running
in the presence of errors are employed (1 mark).
Other correct answers should also receive credit. [6 marks]
(f) Illustrate the four basic symbols
used in Nassi-Schneiderman charts. [4]
(f) One mark should be awarded for correctly
illustrating each of the
following symbols:
- Sequence process
- Condition decision process
- Case decision process
- Iteration process
Marks should not be awarded if a process is named and no diagram is
given. [4 marks]
(g) (i) In the context of CASE, what
are high-level and low-level
specifications? [2]
(ii) In the context of CASE, what are integrated tools? [1]
(iii) Describe two forms of prototyping that a CASE tool might support.
[2]
(g) (i) High level specifications describe
user requirements such as
input, output, and performance expectations (1 mark), while low
level specifications address how high level requirements might be
met through specific details (1 mark).
Other correct answers should also receive credit. [2 marks]
(ii) Integrated tools provide an environment that automates key tasks
throughout the entire development life cycle.
Other correct answers should also receive credit. [1 mark]
(iii) A prototype showing the organisation and layout of data may
be
produced (1 mark), or a prototype may produce a working system
(1 mark). [2 marks]
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