CP1 Computing June 2009

[1]

Two different types of programming errors are syntax errors and logical errors.

(a)

Describe what is meant by the term syntax error and give an example

[2]

an error in using the syntax rules of the language
Eg. a spelling mistake PRUNT instead of PRINT

(b)

Describe what is meant by the term logical error and give an example.

[2]

an error that gives an incorrect result
Eg. an incorrect arithmetic calculation
Total = Amount +Discount ...instead of... Total = Amount-Discount

[2]

Many physically handicapped people use computers. Describe two features of a human computer interface (HCI) which would make it suitable for use by a physically handicapped person.

[2]

speech recognition - the user can issue instructions verbally
touch screen - the user can select options by touching the screen with fingers or a pointing device.

[3]

Krystyna Batowski works for a large organisation which keeps computer records of all its employees.

There are a number of grades of staff in the organisation and Krystyna is on Grade D.
Different employees get different numbers of days of holiday per year and Krystyna gets 28 days.
It is possible to be a member of the pension scheme and Krystyna has chosen to be a member.

(a)

The above information refers to four different types of data. Write down the different types of data, and give an example taken from the above information about Krystyna in each case.

The first one is done for you.

Data Type 1 : String
Example : Krystyna Batowski

[3]

Data Type 2 : Integer
Example : 28
Data Type 3 : Character
Example : D
Data Type 4 : Boolean
Example : True (Member of the pension scheme)

(b)

Name a fifth data type, and describe an example of information about each employee in the above example which could sensibly be stored in this data type.

[2]

Data Type : Real
Example : Hourly pay rate (£) - 24.50

(c)

Why can all the data for one employee not be stored in an array?

[1]

because there are different data types. For an array, all the data must be of the same type.

[4]

A new computer system has been installed in a school office. Documentation is supplied with the system.

(a)

What type of documentation will be helpful to the school office staff?

[1]

user documentation (user manual)

(b)

What type of documentation will be helpful to a future maintenance programmer?

[1]

technical documentation

(c)

The programs in the new computer system contain two types of self-documentation. Explain each of the following:

(i)

self-documenting identifiers;

[1]

meaningful names for identifiers (variables and constants)
Eg A constant called 'VatRate' and not just 'V'

(ii)

self-documenting code.

[1]

Comments written into the code providing additional explanation.

[5](i)

A list of values is in no particular order. A computer program compares each value in the list against a value input until either a match is found or the end of the list is reached.

(a)

Give the full name for this process.

[2]

linear search

(b)

If the value is not matched, what should happen when the end of the list is reached?

[1]

a message 'Value not found' should be output.

(ii)

A binary search is an operation often used in computer programs.

(a)

When it can be used, what is the benefit of using a binary search over other types of search?

[1]

finding values is faster

(b)

It is known that for a binary search on an array of 1000 data items, the maximum search length is about 10. Assuming this is true, what will be the maximum search length for an array of 4000 items?

[1]

[6](i)

Languages like HTML are often used to develop web pages. Describe three features which make such languages suitable for this purpose.

[3]

hyperlinks - to provide navigation between pages
embedding of graphics, videos and sound clips in web pages
scripting - small programs can be included in the page to allow some interactivity

(ii)(a)

One major type of software is applications software. Describe what is meant by the term applications software.

[1]

programs that carry out specified tasks for the user

(b)

Give an example of applications software.

[1]

a spreadsheet program

(c)

Name the other major type of software.

[1]

system software

[7]

A school secretary uses an integrated software package which provides a number of elements.

(a)

One of these elements is a word processor. Name two other elements you would expect to see in an integrated package.

[2]

database
spreadsheet

(b)

Two features of the integrated package that the school secretary uses are mail-merge and macros.

(i)

Describe the mail-merge feature in detail, giving an example of how the secretary might use mail-merge.

[3]

a document is created using a word processor...
...that includes fields from a database when output.
A personalised letter to pupils giving times of their exams

(ii)

Describe the macro feature in detail, giving an example of how the secretary might use macros.

[3]

a single instruction, run using a specified name...
...that executes a stored sequence of instructions.
A macro could be used to create a new document in a word processor and set up the font settings and letterhead at the top of the page ready to type the letter.

[8]

The Government is very worried about the amount of petrol being used and the amount of pollution caused by the cars in the country. The Government is considering whether to charge yearly tax for all the petrol cars in the country according to the official petrol consumption figures (in miles per gallon) and the carbon dioxide emissions produced (in grammes per km).

The algorithm under consideration is shown below:

1	input Emission
2	input Consumption
3	if ((Emission > 170) OR ((Emission > 160) AND (Consumption < 35)))
4		then output "£200 tax"
5		else if ((Emission > 150) OR ((Emission > 140) AND (Consumption < 35)))
6			then output "£150 tax"
7			else output "£100 tax"

(a)(i)

State what the output will be when the inputs are:
Emission = 135 Consumption = 30

[1]

£100 tax

(ii)

State what the output will be when the inputs are:
Emission = 175 Consumption = 40

[1]

£200 tax

(iii)

State what the output will be when the inputs are:
Emission = 145 Consumption = 40

[1]

£100 tax

(iv)

State what the output will be when the inputs are:
Emission = 155 Consumption = 40

[1]

£150 tax

(b)

A change is made in line 5 of the algorithm as shown below:

5	else if ((Emission > 150) OR (Consumption < 35))

(i)

State which of parts (a)(i) to (a)(iv) now gives a different output.

[1]

(a)(i) would be £150 tax

(ii)

Briefly explain why the Government may have made this change.

[1]

to charge a higher tax for all cars with low petrol consumption no matter what their emissions are.

[9]

A specialist shop repairs antique clocks and watches, and keeps quite a large supply of suitable spare parts. Sometimes, however, a part may be required which is not kept in stock by the shop. When this happens, the shop owner contacts a national trade organisation which keeps a larger range of spare parts in stock.

The situation described is shown below:

(a)

Diagrams like this are often used in discussion between software developers and users. Give one reason why this is the case.

[1]

diagrams are easier to understand than text for complex processes

(b)

What type of object does the following shape represent?

[1]

data store

(c)

Write down the shape used in the diagram to represent a data flow.

[1]

(an arrowed line)

(d)

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

[1]

shop's stock database

(e)

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

[1]

shop availability

(f)

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

[1]

trade organisation stock database

(g)

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

[1]

check if in stock at trade organisation

[10]

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

The developers of a new computer system need to consider a number of issues. Two of these issues are the type of changeover to be used and the future maintenance of the programs in the new system.

Describe in detail giving relevant examples where appropriate:

the different types of changeover
the three types of program maintenance
how a computer program can be designed to be easily maintainable.

[9+3]

Direct changeover means the old system is stopped and the new system is started immediately. There could be problems if the new system is not working correctly.
With Parallel Running, both old and new systems are run at the same time until the new system is running well, at which time the old system can be dropped.
Phased changeover involves introducing part of the new system. If it is running correctly, then another part of the new system can be introduced, and so on until the whole new system is running.
Piloting means the new system is tried with only part of the company (Eg one branch or one section). When it is working well, another part of the company starts to use the new system and so on.
Corrective maintenance is needed if there are bugs in the system that need to be corrected.
Perfective maintenance involves the programmers trying to make the programs work better. Eg. Trying to make them run faster or use resources more efficiently.
All businesses change so Adaptive maintenance may be needed to make sure the programs are still appropriate.
Programs will be easy to maintain if they are designed well - written using simple well-structured code, and well documented so that other programmers can easily understand the algorithms used.