CP1 Computing June 2008

[1]

A human computer interface (HCI) is usually designed to make the computer system as easy to learn and use as possible.

Describe three features of an HCI which will make it easy to learn and use.

[3]

easily recognisable icons depicting applications
point-and-click method of selection
hierarchy of menus

[2]

One type of program maintenance is perfective maintenance.

Name two other types of program maintenance and describe, in each case, a situation when it would be necessary.

[4]

corrective maintenance
...needed to correct any bugs that arise in the system
adaptive maintenance
...needed to adapt the system to the changing needs of the business

[3](a)

Describe why it is useful to write a computer program in small clearly documented sections.

[2]

small problems are easier to solve than large ones - so program coding is easier
program maintenance is easier if the sections are fully documented.

(b)

Describe why it is useful to use standard modules when writing a computer program.

[2]

program development time is cut down as the procedures do not have to be written and tested again
standard modules have already been tested so the procedures are sure to work.

(c)

Explain the difference between a high-level programming language and a low-level programming language.

[2]

high level - code is similar to the spoken language (English)
low level - code is similar to the machine code that the computer executes.

[4]

Systems software is one of the two major types of software.

(i)

Describe what is meant by the term systems software.

[1]

Programs that help in the operation of the computer

(ii)

Give an example of systems software.

[1]

the operating system E.g. Windows

(iii)

Name the other major type of software.

[1]

application software

[5](a)

A Chemistry student records various items of data for entry into a computer program.

The data includes:

an observation code (for instance A, B, C...)
the temperature of a liquid in degrees Celsius (for example 24.6)
the name of the chemical used (for example sodium bicarbonate)
whether or not there is a colour change in the liquid

(i)

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

(I) the observation code

[1]

character

(II) the temperature

[1]

real

(III) the chemical name

[1]

string

(IV) whether or not there is a colour change

[1]

boolean

(ii)

Name one data type other than those used in (i)

[1]

integer

(iii)

A record could be used to store all four data items from one experiment.
Why would a record be suitable in this case?

[1]

A record can store data of differing types.

(b)

There are a number of students in the Chemistry class and their marks for a number of tests are recorded by their teacher.

Give the name of a data structure which would be useful for recording all the students' marks, and draw a diagram to illustrate this data structure.

[1,2]

two-dimensional array

	Test 1	Test 2	Test 3
Jones J	15	32	16
Thomas P	16	38	19
Williams C	12	25	12
Smith J	19	29	18

[6]

The basic cost of an item does not include VAT.
The following program extract, which contains two errors, is intended to calculate the cost, including VAT, of a number of items purchased.

Statement
1	VatRate = 0.175
2	repeat
3		input BasicCost
4		Vat = BasicCost * VatRate
5		CostWithVat = BasicCost - Vat
6		outptu CostWithVat
7	until BasicCost = -999

(i)

For each of the two errors, name the type of error and write down the corrected statement.

[4]

(Line 6) outptu should be output
syntax error
(Line 5) BasicCost - Vat should be BasicCost + Vat
logical error

(ii)

Name a third type of programming error.

[1]

run-time error

(iii)

(I) What is the purpose of the value -999 in statement 7?

[1]

to indicate the end of the input sequence of costs

(II) What is the name given to a value which is used in this way?

[1]

rogue value

[7]

Cemaes Driving School employs a number of driving instructors and office staff. Cemaes use a paper-based system to store and manage customer names and addresses and also bookings for driving lessons.

The owner of Cemaes employs a systems analyst to investigate the current system and design a new computer-based system. The systems analyst asks current users to fill in a questionnaire and also interviews current users of the system.

(i)

Describe one advantage of using questionnaires rather than interviews.

[1]

saves time - a number of questionnaires can be done at the same time.

(ii)

Apart from questionnaires and interviews describe one other method which the systems analyst might use to investigate the current system.

[1]

observation - the systems analyst can spend some time in the office observing what people do and what problems arise.

(iii)

The systems analyst produces a requirements specification. Describe what is likely to be contained in a requirements specification.

[2]

a report on what the programs need to do
what data needs to be collected, what processing needs to be done on it and what the resulting output should be.

[8]

People travelling to some countries are advised that they should be vaccinated against certain diseases.

For one such disease, travelling to some countries is considered to be medium risk, travelling to other countries is considered to be low risk, and travel to all other countries is considered to be of no risk at all.

The age of the traveller is also important, with very young or elderly people being at different levels of risk.

There are two types of vaccination (A and B) which are suitable in different circumstances.

The algorithm shown below is used to determine whether the traveller should be vaccinated.

Statement
1	input CountryRisk
2	input Age
3	if ((CountryRisk = medium) AND (Age > 70))
4		then output "Vaccinate with A"
5		else if (((CountryRisk=medium) AND (Age < 5)) OR ((CountryRisk=low) AND (Age > 70)))
6			then output "Vaccinate with B"
7			else output "Do not vaccinate"

(i)

(I) Write down the output for a traveller aged 72 travelling to a low risk country.

[1]

Vaccinate with B

(II) Write down the output for a traveller aged 4 travelling to a low risk country.

[1]

Do not vaccinate

(III) Write down the output for a traveller aged 35 travelling to a medium risk country.

[1]

Do not vaccinate

(IV) Write down the output for a traveller aged 72 travelling to a medium risk country.

[1]

Vaccinate with A

(ii)

The above algorithm is correct. However it is incorrectly entered, so that the word "OR" in statement 5 is changed to "AND" as shown below.

else if (((CountryRisk=medium) AND (Age < 5)) AND
((CountryRisk=low) AND (Age > 70)))

Describe in detail what will happen if this incorrect algorithm is used instead of the correct algorithm.

[2]

People who need Vaccine B would not receive it. (Those aged less than 5 going to medium risk country and those over 70 going to a low risk country)

[9]

A company hires items, for instance decorating or building equipment, to customers. When a customer makes an enquiry, the staff check the availability of the item. If the item is not available for any reason, this fact is recorded, and each month, a decision is made by the company whether or not to purchase any of the items.

The diagram below illustrates the situation described.

(i)

What name is given to this type of diagram?

[1]

data flow diagram

(ii)

What type of object does the shadow box represent?

[1]

external entity

(iii)

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

[1]

(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]

Items (stock) database

(vi)

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

[1]

Unavailable items database

(vii)

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

[1]

Decide whether to buy

[10]

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

Staff in a small company use a computer system which includes an integrated package, providing word processing, spreadsheet, database and other functions. Features available include mail-merge, macros, sorting, searching and data portability.

Describe in detail the features highlighted above, and how the staff might use each of these features.

[8+3]

A mail-merge is used to produce a number of similar documents by creating a standard form and merging it with fields from a database. The values of the fields are inserted into the document before it is printed. The staff may use a mail-merge to send personalised letters to customers informing them about new products.
A macro is a pre-defined sequence of instructions that is given a name and can be executed with a single instruction. Staff may use it for frequently used tasks such as creating a letterhead on a document.
Sorting data means putting the data into numerical or alphabetical order of key field values. Customer data may be sorted into numerical order of sales to find out which customers have bought the most goods.
Searching data means finding data that satisfies certain criteria. The staff may search for all customers that live in Cardiff.
Data portability means that the data can be transferred easily from one program to another. For example, the data in a spreadsheet can be transferred into a document.