Computing (Modular) 
 CP1
January 2004
(1.5 Hours)

[1](a) School students are to be surveyed to find out if they will be applying to university.

Name a suitable data type for storing each of the following, giving a reason for your choice in each case:

 

  
(i) the number of A level subjects the student is taking; [2]
   
(ii) whether the student is intending to apply to university or not; [2]
   
(iii) the mean mark gained in school examinations, for instance 62.4; [2]
   
(iv) the student's home telephone number, for instance 01970 123456. [2]
   
(b) State one data structure which could store all four items of data given in part (a) for one student as a single item. [1]
   
 
[2](a)(i) A computer program includes a line in which a command word is misspelled. What type of error is this? [1]
   
(ii) Another program is correctly written but fails to run correctly. What type of error is this? [1]
   
(iii) Another program appears to run correctly, but its output is wrong because it contains an incorrect calculation. What type of error is this? [1]
   
(b) What is the function of a translation program when applied to a source program? [1]
   
 
[3] A firm sends letters to members of the public. It does this by combining name and address data from one part of an integrated package, into a standard letter produced in another part of the same package.

 

  
(i) What name is given to the operation when data are combined in this way? [1]
   
(ii) What two parts of the integrated package would be useful for this operation? [2]
   
 
[4](a) A computer program runs through a list of numbers, comparing each number against a fixed number until either a match is found or the end of the list is reached.

 

  
(i) Is this operation a sort or a search? State what type of sort or search it is. [2]
   
(ii) If the number is not matched, what should happen when the end of the list is reached? [1]
   
(b) Under certain circumstances, a binary search can be used.  
(i) When can it be used, what is the benefit of using a binary search over other types of search? [1]
   
(ii) Under what circumstances can a binary search be used? [1]
   
 
[5](a) A systems analyst can use a number of techniques to find out how an existing system works.
These include:
  • asking staff to complete questionnaires
  • interviewing staff who use the current system

 

  
(i) Describe one advantage of using questionnaires over interviewing staff. [1]
   
(ii) State two other methods which might be used to find out about the current system. [2]
   
(iii) The systems analyst produces a requirements specification. Describe two elements which this should contain. [2]
   
(b) Describe two activities which should take place during the testing of a new computer system. [2]
   
(c) For a new computer system to be successful, it needs to be cost effective. State one other basic requirement. [1]
   
 
[6] Languages such as HTML are used in the development of web pages. describe two features which make such languages suitable for this purpose. [2]
   
 
[7] One type of software is applications software.  
(i) Describe what is meant by the term applications software. [1]
   
(ii) Give an example of applications software. [1]
   
(iii) State another type of software. [1]
   
(iv) Give an example of the type of software you stated in part (iii) [1]
   
 
[8] Before a teacher can be employed at a school, the headteacher has to check whether the teacher has a criminal record. In every case, after this check, the teacher receives a letter stating whether he or she has been successful or not.

This situation is shown in the diagram below.

  
 

 

  
(i) This diagram is called a data flow diagram. Give two reasons why data flow diagrams are useful during systems analysis. [2]
   
(ii) What type of object does the open box in the diagram represent? [1]
   
(iii) What type of object does the shadow box in the diagram represent? [1]
   
(iv) Give a suitable name for the object shown as a in the diagram. [1]
   
(v) Give a suitable name for the object shown as b in the diagram. [1]
   
(vi) Give a suitable name for the object shown as c in the diagram. [1]
   
 
[9](a) Describe what is meant by the term global variable in a computer program. [1]
   
(b) Describe what is meant by the term local variable in a computer program. [1]
   
 
[10] A train company uses an algorithm to determine whether a journey is peak or off-peak. On weekdays, early morning journeys are charged at full price (peak). After a certain time in the morning, journeys are charged at a reduced rate (off-peak). At weekends all journeys are off-peak. Currently, the month of travel makes no difference to the price charged, although it is input to the algorithm.

The algorithm used is shown below:

   
 
Line  
   
1 input day-type
2 input time
3 input month
4  
5 if ((day-type = weekday) AND (time < 10))
6      then output "peak"
7      else output "off-peak"
  
(i) State what the output will be if the three inputs are: [3]
 
  day-type time month
I weekday 9 January
II weekday 9 August
III weekend 11 December
 
   
(ii) A change is made in line 5 so that it now reads:  
 
Line  
...  
5 if ((day-type = weekday) AND (time < 10)) OR 
((day-type = weekend) AND (month = August)))
...  
  
I Explain the difference this represents to the company's charging policy. [1]
   
II Give an example of data which illustrate this difference. [1]
   
 
11. In the following question, additional credit (up to 3 marks) will be given if your answer demonstrates skill in written communication.

 

 [8+3]
  The computer section of a large company is intending to replace an existing computer system. The programmers plan to use a top-down design method, and use standard modules. When the system is completed, the company intends to use a direct changeover.

The company is very concerned to design a human-computer interface (HCI) which is easy-to-use for non-experts and to ensure that the system will be easily maintainable.

Describe in detail why the company might wish to use a top-down design method and standard modules, and also a direct changeover. Also describe in detail how they might achieve a system which has an easy-to-use HCI and which is easily maintainable.