CP1 Computing January 2009

[1]

State two different types of computer system documentation, indicating in each case the type of person who would find this documentation helpful.

[2]

technical documentation...for programmers and other experts
user documentation...for the user

[2]

A supermarket chain uses a computer system to store large amounts of data about its customers who hold one of its loyalty cards. The data stored includes:

Customer name
Number of complete years as loyalty card holder
Average weekly spend in 2008
Address
Telephone number

(i) (I)

State one of the above data items which could sensibly be stored as an integer data type.

[1]

Number of complete years as loyalty card holder

(II)

State one of the above data items which could sensibly be stored as a real data type.

[1]

Average weekly spend in 2008

(III)

State any two of the above data items which could sensibly be stored as a string data type.

[1]

Customer name
Address
Telephone number
(any two)

(IV)

State an additional data item about each customer which could sensibly be stored as a boolean data type.

[1]

Gender
(any two-state data)

(ii) (I)

Name a data structure which could hold all the items relating to one customer.

[1]

Record

(II)

Explain why this data structure is suitable in this case.

[1]

A record can store data of different types.

3. (a)

When a new computer system is being developed, a decision is made over the type of changeover from the old system to the new system. State two methods of changeover, and describe the benefits of the method in each case.

[4]

Type 1:

Direct changeover

Benefit:

No need for duplication of work

Type 2:

Parallel running

Benefit:

If there are problems with the new system, the old system can still be used.

(b)

Various types of maintenance may be necessary for new computer programs. For instance, adaptive maintenance may be necessary if there is a change of operating system.

Name and describe two other types of program maintenance.

[2]

Type 1:

Corrective maintenance...corrects any bugs

Type 2:

Perfective maintenance...improves the performance of the programs

It is very important that a human computer interface (HCI) is intuitive, as this usually makes it easy to learn. Describe three other aspects of an HCI which would make it particularly suitable for a novice user.

[3]

Aspect 1:

selection of options using a mouse pointer

Aspect 2:

can be customised to what user wants

Aspect 3:

consistent with other packages the user may know

5. (a)

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

[1]

data can be found faster

(b) (i)

It is required to search for the number 34 in the following array:

12 34 17 19 30 27 20 26

Name a type of search which is suitable in this case.

[1]

linear search

(ii) (i)

It is required to search for the number 36 in the following array:

15 18 18 21 26 31 36 38

Name another type of search which is suitable in this case, but would not be suitable in part (b)(i)

[1]

binary search

(ii)

When this type of search is used write down one possible order in which the number in the array will be accessed to the complete search for 36.

[2]

21 31 36
or... 26 36

6. (a)

A two-dimensional array contains a large number of data values. What must be true of all the data values in the array?

[1]

All the data must be the same type

(b)

A certain computer language allows an integer data to be subtracted from a real data type. What data type would you expect the result of the subtraction to be?

[1]

real

7.(a)

Describe a feature which would be useful in a computer language used for a scientific application.

[1]

High precision and complex mathematical calculations - Eg using trigonometric functions

(b)

Describe what is meant by the term systems software.

[1]

programs that help in the running of the computer

A computer program is intended to calculate the mean of a set of values representing examination marks (out of a possible 100). The following values are input to the program.

64 57 56 75 63 47 63 48 92 45 59 41 32 64 26 55 -999

(i)

The last value (-999) is called a rogue value.

(I)

What is the purpose of a rogue value?

[1]

it lets the computer know when the input data is finished.

(II)

Why would -999 be a suitable rogue value in this case?

[1]

it is of the correct data type (integer) and is not a value that could be achieved.

(ii)

The program contains an error. It adds up all the values entered, including the rogue value, then divides by the number of values.

(I)

Name this type of programming error.

[1]

Logical error

(II)

Name another type of programming error giving an example.

[2]

syntax error - Eg not spelling a command correctly (Eg PRUNT instead of PRINT)

A water company monitors the amount of water in its reservoirs and the amount of rain falling. During a water shortage, the company is able to ban its customers from using hosepipes. In extreme conditions, the water company has the power to ration the water supply to its customers, by turning off the supply for several hours per day.

The algorithm, used by the company is shown below:

Statement
1	input ReservoirLevel
2	input DaysSinceLastRain
3	if ((ReservoirLevel < 20%) OR
	((ReservoirLevel <30%) AND (DaysSinceLastRain > 21)))
4	then output "Rationing"
5	else if ((ReservoirLevel < 40%) AND (DaysSinceLastRain > 14))
6	then output "Hosepipe ban"
7	else output "Normal"

(i)

State what the output will be when the inputs are:

(I)

Reservoir level = 35% Days since last rain = 16

[1]

Hosepipe ban

(ii)

Reservoir level = 32% Days since last rain = 12

[1]

Normal

(III)

Reservoir level = 15% Days since last rain = 12

[1]

Rationing

(IV)

Reservoir level = 28% Days since last rain = 25

[1]

Rationing

(ii)

The water company decides to change statement 3 so it becomes:

3	if ((ReservoirLevel < 20%) OR
	((ReservoirLevel <25%) AND (DaysSinceLastRain > 21)))

(I)

State which part or parts of (i)(I) to (i)(IV) now gives a different output.

[1]

(IV)

(II)

What will the new output or outputs be?

[1]

Hosepipe ban

10.

When a student apples to do a course at a particular music college, he or she completes an application form and asks someone (a referee) to supply a reference to the College. When the College receives the application, its admissions tutor checks on a national database any musical examination results claimed by the student. The student is then interviewed and if successful he or she is added to the list of students approved for entry to the College.

The situation described is shown in the data flow diagram below:

(i)

Why do systems analysts find data flow diagrams very useful?

[1]

Diagrams can show complex situations in a more easily understandable way than text

(II)

What type of object does the rounded box represent?

[1]

Process

(iii)

Draw the shape used in the diagram to represent an external entity.

[1]

(iv)

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

[1]

Application details (form)

(v)

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

[1]

Referee

(vi)

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

[1]

National Database of Music Examinations

(vii)

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

[1]

Interview student

11.

A small gardening firm uses a software package which combines a word processor, spreadsheet and other elements.

(i)

What is the name for this sort of software package?

[1]

An Integrated Software Package

(ii)

Apart from a word processor and spreadsheet, name one other element which might usefully be included in the software package.

[1]

Database

(iii)

Describe what is meant by a mail-merge facility and give an example of how the gardening firm might use this facility.

[2]

Fields from a database are inserted into a standard document to produce a number of similar documents.

(iv)

The software package includes another facility whereby a set of key-strokes can be recorded by the user then called up by a single key-stroke. What is the name given to this facility?

[1]

Macro

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

A software house is developing a major new software system for a large retailer. It will be necessary to carry out a requirement analysis and a top-down design method will be used, resulting in programs consisting of small, clearly documented sections.

Describe how a requirement analysis is carried out and explain what is meant by a top-down design method. Explain the benefits of programs consisting of small, clearly documented sections. particularly to a maintenance programmer.

[8+3}

A Requirement Analysis may involve the interviewing of staff or customers, or asking them to fill in questionnaires. Any existing documentation such as manuals or staff instruction sheets may also be studied. Current practice may be observed to determine how the current system works and what data is stored. Data Flow Diagrams of the existing system may be drawn.
Top-down design methods involve breaking down the problems into successively smaller tasks until each small task can be easily solved.
Small sections of program are easier to understand, and hence easier to alter if necessary. Clear documentation also helps to make a program easier to understand. A maintenance programmer will not be able to alter a program unless he understands it fully. The process of testing a program is simpler for small programs and tasks such as coding or testing can be distributed among a team of different programmers. Small sections of code may also be put in a library and used again in other programs.