AS COMPUTER SCIENCE Paper 1

MERGED QUESTION PAPER AND MARKING SCHEME



AS
COMPUTER SCIENCE
Paper 1


Tuesday 14 May 2024 Afternoon Time allowed: 1 hour 45 minutes
Materials
For this paper you must have:
• a computer
• a printer
• appropriate software
• the Electronic Answer Document
• an electronic version and a hard copy of the Skeleton Program
• an electronic version and a hard copy of the Preliminary Material
• an electronic version of the Data File SimulationData.txt
You must not use a calculator.

Instructions
• Type the information required on the front of your Electronic Answer Document.
• Before the start of the examination make sure your Centre Number, Candidate Name and
Candidate Number are shown clearly in the footer of every page (not the front cover) of your
Electronic Answer Document.
• Enter your answers into the Electronic Answer Document.
• Answer all questions.
• Save your work at regular intervals.

Information
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 75.
• No extra time is allowed for printing and collating.
• The question paper is divided into three sections.

Advice
You are advised to allocate time to each section as follows:
Section A – 20 minutes; Section B – 25 minutes; Section C – 60 minutes.

At the end of the examination
Tie together all your printed Electronic Answer Document pages and hand them to the Invigilator.

Warning
It may not be possible to issue a result for this paper if your details are not on every page of your
Electronic Answer Document.




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, 2


Section A

You are advised to spend no more than 20 minutes on this section.

Enter your answers to Section A in your Electronic Answer Document. You must save this
document at regular intervals.

Question 04 in this section asks you to write program code starting from a new
program/project/file.

You are advised to save your program at regular intervals.


0 1 Figure 1

S1  "011101"
S2  "001100"
C  "0"
R  ""
FOR J = 0 TO 5
X  5 - J
D1  S1[X]
D2  S2[X]
IF C = "0" THEN
IF D1 = D2 THEN
S  "0"
C  D1
ELSE
S  "1"
ENDIF
ELSE
IF D1 = D2 THEN
S  "1"
C  D1
ELSE
S  "0"
ENDIF
ENDIF
R  CONCATENATE(S, R)
ENDFOR
OUTPUT R

The function CONCATENATE(X, Y) returns the string formed by concatenating the
string Y to the end of string X. For example, CONCATENATE("cat", "dog")
returns "catdog".

The strings are zero index based.




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, 3


Complete Table 1 by hand-tracing the algorithm in Figure 1.

You may not need to use all the rows in Table 1.

You do not need to indicate that C, D1, D2 and S are strings.

The first row of Table 1 has already been completed for you.


Table 1



S1 S2 C R J X D1 D2 S

"011101" "001100" "0" ""




OUTPUT:



Copy the contents of all the unshaded cells in Table 1 into your Electronic
Answer Document.
[5 marks]




Turn over ►
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, 4


0 2 A program uses both local and global variables.

0 2 . 1 State two differences between local and global variables.
[2 marks]

0 2 . 2 Give two reasons why it is good practice to use local variables.
[2 marks]


0 3 Programmers are encouraged to adopt a structured approach to writing programs.

Explain three reasons for adopting the structured approach.
[3 marks]


0 4 Figure 2 shows an algorithm represented using pseudo-code.

Figure 2

OUT_NOLF "Enter an integer: "
INPUT Number1
OUT_NOLF "Enter another integer: "
INPUT Number2
IF Number1 > Number2 THEN
Number  Number1 DIV Number2
ELSE
Number  Number2 DIV Number1
ENDIF
Count  0
WHILE Count ≠ Number
Count  Count + 1
IF (Count MOD 10) = 0 THEN
OUT_NOLF "X"
ELSE
IF (Count MOD 5) = 0 THEN
OUT_NOLF "V"
ELSE
OUT_NOLF "/"
ENDIF
ENDIF
ENDWHILE

The OUT_NOLF command displays the output without a line feed. The following series
of OUT_NOLF commands will display ABC:

OUT_NOLF "A"
OUT_NOLF "B"
OUT_NOLF "C"




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