CP1 Computing June 2003

1(a)

In a spreadsheet:

(i) describe what is meant by a search facility;

[1]

the ability to find a particular item of data on the spreadsheet

(ii) describe what is meant by a macro, giving an example of its use;

[2]

a single command which performs a sequence of pre-defined instructions.
Example - a macro could be used to set the font, colour and background of a particular cell.

(iii) describe what is meant by data portability, giving an example of its use.

[2]

the same data can be transferred between a number of different programs.
Example - data could be copied from the spreadsheet and pasted into a word processor.

(b)

The same spreadsheet has a human computer interface (HCI) designed for a wide range of users. In each of the following, describe one feature which might be helpful to:

(i) a beginner

[1]

meaningful icons which can be clicked to perform simple tasks

(ii) an expert user.

[1]

tasks with a large number of options or settings available.

2(i)

Data held about each student in a school include his or her:

name
number of subjects being taken
tutor group (A to G)
mean examination mark
decision whether to apply for university (Yes or No)

For one particular student, the data held are:

Clare Morgan
4
D
64.3
Yes

In each case I. to V. state the data type which should be used.

[5]

Text
Integer
Character
Real
Boolean

(ii)

State the data structure which should be used to store all of these data about each student.

[1]

a record should be used.

(iii)

Give one reason why an array could not be used to store all the data about each student.

[1]

the data are of different types.

(iv)

Using a diagram, give an example of student data which could sensibly be stored in a two-dimensional array.

[2]

Eg : Exam marks for a number of different students and a number of different exams.

	English	Maths	Science
Tom Jones	63	67	78
Jane Smith	52	56	65
Wendy Thomas	72	69	64
Ian Davies	38	43	39

3(a)

What is meant by the term syntax error?

[1]

the rules of the language have been used incorrectly.

(b)

The following statement is part of a computer program:

a = b / c

State a circumstance which will cause an execution error when this statement is executed.

[1]

if the value of c was 0.

(c)

The following statement is part of another computer program:

d = e + f

State a circumstance under which this statement could contain a logical error.

[1]

if d was supposed to be the difference and not the sum of e and f.

A national kidney transplant service stores information on hundreds of patients awaiting a kidney transplant. When a donor kidney becomes available, the system checks the donor kidney's characteristics against the details of all the patients. Details of the donor kidney are also stored in a separate database.

The situation described is shown in the diagram below:

(i)

Write down the name for this type of diagram.

[1]

data flow diagram.

(ii)

What type of object does the open box symbol in the diagram represent?

[1]

a data store.

(iii)

What type of object does the arrow symbol in the diagram represent?

[1]

data flow.

(iv)

Give a suitable name for the object shown as a in the diagram.

[1]

patient data.

(v)

Give a suitable name for the object shown as b in the diagram.

[1]

donor kidney data.

(vi)

Give a suitable name for the object shown as c in the diagram

[1]

donor kidney database.

(vii)

When would this type of diagram be useful?

[1]

when designing or changing the computer system.

A newsagent's shop uses a paper-based system to manage its paper delivery service, storing, for instance, data about customer requirements.

Imagine that you are asked by the newsagent to carry out a systems analysis and design for a new computer-based system.

As systems analyst, you will need to carry out a number of tasks.

Describe each of the following tasks in detail, making it clear how you would carry out each task for the newsagent.

(i)

Requirements analysis

[2]

identify the problems of the existing system through interviews, questionnaires and observation.
set aims and objectives for the new system.

(ii)

Evaluation of alternative proposals.

[2]

propose and consider a number of different solutions and designs for the new system.
analyse which of them would be the most suitable (eg most cost effective and socially feasible)

(iii)

Testing.

[2]

design a sequence of tests and select appropriate test data.
run the tests on individual modules and on the whole system, identifying problems which arise.

6(i)

Describe, giving an example, what is meant by the term systems software.

[2]

programs which help in the running of a computer system.
Example - the operating system.

(ii)

Describe, giving an example, what is meant by the term applications software.

[2]

programs which perform specific tasks for a computer user.
Example - a word processing package.

Students on a certain course take six modules during their first year. To progress to the second year, they have to either pass all six modules and achieve a certain mean mark, or pass only five modules with a higher mean mark.

The following algorithm is used for each student.

Line
1	input NumberModulesPassed
2	input MeanMark
3	if (((NumberModulesPassed = 6) AND (MeanMark > 44)) OR ((NumberModulesPassed = 5) AND (MeanMark > 49)))
4	then output "Progress"
5	else output "Do not progress"

(i)

State what the output will be if the inputs are:

I. 5 and 42

[1]

"Do not progress"

II. 6 and 48

[1]

"Progress"

III. 5 and 48

[1]

"Do not progress"

IV. 4 and 60

[1]

"Do not progress"

(ii)

As a result of a change to the course requirements, line 3 is changed to:

...
3	if ((NumberModulesPassed = 6) OR ((NumberModulesPassed = 5) AND (MeanMark > 49)))
...

I. Describe the change to the course requirements.

[1]

If the student passes 6 modules he can progress to the second year no matter what their mean mark is.

II. Give an example of data which demonstrates the change.

[1]

6 and 40
the student can progress whereas before, he could not.

8(a)

Data are often sorted by computers. Why is this a useful operation?

[1]

It is faster to find data if it is sorted.

(b)(i)

When a binary search can be used, why is it preferable to a linear search?

[1]

it is usually faster to find data with a binary search than with a linear search.

(ii)

It is known that, for a binary search, the maximum search length for an array of 1000 data items is 10. Assuming this is true, what would be the maximum search length for an array of 2000 data items?

[1]

maximum search length is 11

(iii)

If a computer takes a maximum of 1 second to do a binary search on a set of 1000 data items, state, with a reason, approximately how long you would expect a binary search to take on a set of 1 000 000 data items.

[2]

maximum search length is 20
..so max time taken would be 2 seconds.

9(i)

Describe what is meant by a local variable in a computer program.

[1]

a variable which exists and can only be referenced inside a subroutine.

(ii)

Describe what is meant by a parameter in a computer program.

[1]

a value passed to a subroutine which can then use it.

10.

In the following question, additional credit (up to 3 marks) will be gained if your answer demonstrates skill in written communication.

When a large computer system is being developed, a number of factors need to be considered. A decision needs to be made over the programming language used. The system needs to be well designed, making use of small clearly documented sections (including self-documentation where possible.) Consideration needs to be given to the changeover to the new system and its maintenance once it is in use.

Describe in detail the importance of each of the factors shown in italics.

[8 + 3]

Some programming languages are designed for specific purposes, so it will depend on the purpose of the program being designed as to which programming language would be most appropriate.

The program will need to be broken down into self-contained modules which may be independently designed, developed and tested. Small sections are easier to develop and less likely to have errors. These sections must be clearly documented for ease of development and for future changes by others not involved in the original development. Program coding needs to use self-documentation (meaningful variable names and plenty of comments) so that it is easily understood by other programmers.

When a new system is implemented, the changeover may be done directly, or by parallel running the new system alongside the old one until all problems have been ironed out. A gradual phased changeover may also be used.

Even when a system is up and running, there may be a need for maintenance - perfective maintenance to make improvements, adaptive maintenance to keep up with changes in the company or corrective maintenance to solve any problems. If the design of the system has been done well this should make maintenance relatively easy and trouble-free.