CP1 Computing June 2004

1(a)

Employee information held on a computer system includes the employee's name, their number of whole years with the firm, their department name and whether they are in the firm's pension scheme.

(i)

State the most appropriate data type for each of the following:

Employee's name;

[1]

string

Number of whole years with firm;

[1]

integer

Department name;

[1]

string (or character)

Whether in pension scheme.

[1]

boolean

(ii)

Give an example of other employee information which could sensibly be stored in a real data type.

[1]

Eg. date of birth; job description; pay rate;

(iii)

Using a labelled diagram, give an example of employee information which would best be stored in a two-dimensional array.

[2]

	Year
Sales Figures	2004	2005	2006
Jan	£250	£521	£409
Feb	£320	£546	£640
March	£407	£308	£530
April	£398	£290	£820
etc...	...	...	...

The blue cells are the two-dimensional array of currency data.

(b)

Give one reason why it is generally not sensible to store telephone numbers in an integer data type.

There is never any need to perform mathematical calculations on telephone numbers.

A computer package has a Human-Computer interface (HCI) designed for a variety of users. Describe two features in each case which would be helpful for :

(i)

a beginner :

[2]

Easily recognisable icons to represent applications or options.
The use of a pointer and a mouse to select options.

(ii)

an expert user:

[2]

Command line - the ability to type in and enter instructions and option parameters.
A hierarchical system of menus offering options to choose from.

A certain computer program analyses data on the number of items bought in a clothes shop by each customer. The data below is input and the computer then carries out relevant calculations.

3 2 5 4 2 4 1 3 2 2 4 8 -1

(i)

What is the name and purpose of the last number (-1)?

[2]

It is a rogue value.
...and it is used to indicate the end of the input data.

(ii)

Why is -1 a suitable value for this purpose?

[1]

It is a value which is not going to arise in the data.

4. (a)

A certain integrated package combines word processing, spreadsheet and database facilities. The package allows users to create their own macros, and there is also a programming facility.

(i)

Describe what is meant by the term macro and give an example of its use.

[2]

A macro is a single command representing a programmed sequence of instructions.
A macro may be used in a word processing program to set up a document's template.

(ii)

Describe one benefit of having a programming facility.

[1]

It is possible to customise the software.

(b)

An integrated package is an example of applications software. Name a different type of software and give an example of this type of software.

[2]

Systems software
Example - an operating system.

5. (a)

Computer programmers often use standard modules and self-documenting identifiers.

Explain each of these terms, giving an example in each case:

(i)

standard module ;

[2]

a standard module is a set of previously coded and tested subroutines that can be incorporated into a program.
Example : A set of mathematical functions may be included in a module.

(ii)

self-documenting identifier.

[2]

Self-documenting identifiers are variables and constants that have meaningful names, explaining what they are.
Example : A variable called 'VATRate'

(b)

Errors often occur during program development. Describe each of the following types of error, giving an example in each case:

(i)

syntax error;

[2]

An error in the use of the language.
Example : A mis-spelled instruction like PRUNT instead of PRINT

(ii)

logical error.

[2]

The program runs but the result is incorrect.
Example : Two variables are added instead of subtracted.

(c)

Explain why careful version control is important when developing computer programs.

[1]

Changes must always be made to the latest version of a program, otherwise some previous changes may not be included.

(d)

Programs need to be maintained. One type of maintenance is adaptive maintenance. Name one other type of maintenance, and describe when it would be necessary.

[2]

Corrective maintenance - needed when bugs are found in the program.

Perfective maintenance - needed to improve the performance of a program.

6. (a)

A binary search is used to search for the number 12 in the following array:

Write down in order the numbers which are accessed to complete the search.

[2]

16 9 12

(b)

An attempt is made to use a binary search to search for the number 47 in the following array:

(i)

Explain why the binary search is not appropriate in this case.

[1]

To use a binary search the data must be in sorted order - these are not!

(ii)

Name a type of search which would be appropriate in this case.

[1]

Linear search.

Police fraud officers are concerned about a group of businesses and have decided to investigate any business in this group where the profits announced are very large or are considerably higher than in the previous year.

The algorithm used is shown below:

Statement

1. input ProfitThisYear
2. input ProfitLastYear
3. if ((ProfitThisYear>1 000 000) OR ((ProfitThisYear>500 000) AND (ProfitThisYear>1.5*ProfitLastYear)))
4. then output ''Investigate''
5. else output ''Don't investigate''

(a)

State what the output will be when:

(i)

the inputs are 600 000 and 200 000;

[1]

Investigate

(ii)

the inputs are 600 000 and 600 000;

[1]

Don't investigate

(iii)

the inputs are 2 000 000 and 3 000 000.

[1]

Investigate

(b)

The word OR is correctly used is statement 3 above. If it were replaced with the word AND, as shown below, the algorithm would not produce the required output.

3. if ((ProfitThisYear>1 000 000) AND ((ProfitThisYear>500 000) AND (ProfitThisYear>1.5*ProfitLastYear)))

Tick one box to show which of the inputs given in part (a) would give the same output as the original algorithm.

inputs	tick one box
600 000 and 200 000
600 000 and 600 000
2 000 000 and 3 000 000

[1]

inputs	tick one box
600 000 and 200 000
600 000 and 600 000	TICK
2 000 000 and 3 000 000

A bank has a national call centre where customers can telephone to make enquiries about their account. Sometimes, during the phone conversation, the customer decides to make a complaint, and all complaints are logged by the call centre. This situation is as shown in the following data flow diagram:

(i)

A systems analyst finds it very useful to show this type of diagram to users. Give one reason why this might be the case.

[1]

It shows the flow of data through a system in an easy-to-understand way.

(ii)

What type of object does the rounded box in the diagram represent?

[1]

a process

(iii)

Draw the shape used in the diagram to represent a data store.

[1]

(an open ended box like the Complaints log)

(iv)

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

[1]

customer enquiry

(v)

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

[1]

customer accounts

(vi)

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

[1]

log complaint

An algorithm is to be developed to investigate world-wide climate change.

(i)

Give one reason why it will be very important to document this algorithm carefully.

[1]

programmers who may need to change it in the future will need to understand how it works.

(ii)

The algorithm is to be implemented using a high-level computer language. What is meant by the term high-level computer language?

[1]

a language nearer to English than to machine code.

(iii)

It will be important in this case to choose a suitable high-level language. Describe one feature of a suitable language which will be particularly useful.

[1]

mathematical functions that can perform calculations to a high degree of accuracy.

(iv)

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

[1]

a variable that can be used anywhere in a program.

(v)

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

[1]

a variable that can only be used inside the subroutine that it has been declared in.

10.

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

A sports club employs a systems analyst to enable it to computerise all the information it holds about members and sporting events.

The systems analyst will need to carry out a requirements analysis, then produce a requirements specification, and will need to select suitable software.

The systems analyst will also need to specify the most suitable type of changeover to be used.

Describe in detail how the systems analyst would carry out each of the four steps in italics above.

[7+3]

The systems analyst would investigate the way the current system works by interviewing members and staff at the sports club, or asking them to fill in questionnaires. The analyst would probably spend some time at the club observing how the data is recorded, and reading any existing documentation.

This will enable the analyst to produce a requirements specification - a set of objectives that the new system will need to meet, together with the methods of evaluation. These will let the analyst know whether the targets have been met.

Part of the requirements analysis will be to decide on the software to be run on the new system. This will depend on the amount and type of data that needs to be held and the IT skills of the people who are going to use it.

When the new system has been designed, the method of changeover to the new system will need to be decided. A direct changeover would mean stopping the old system and starting the new one straight away, but this may be a problem if the new system is found to have bugs in it. It may be useful to carry out parallel running - running the new and old systems together until people are confident the new system works perfectly. A gradual change may be better using a phased changeover.