AS Computer Science Paper 1 | Actual Exam Question Paper and Mark Scheme (Merged)

PMT




AS
COMPUTER SCIENCE
Paper 1


Tuesday 16 May 2023 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 Files prog1.txt, prog2.txt and prog3.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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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 05 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 A security system uses a motion sensor, a keypad and an alarm bell.

The system operates as follows:

• the system is initially off
• when the system is switched on it goes into sensing mode
• the system can be switched off at any time by entering the correct code on the
keypad
• if the system detects movement while in sensing mode it goes into alert mode
• after the system has been in alert mode for 10 seconds, it enters the alarm bell
ringing mode
• if an incorrect code is entered on the keypad, once the system has been switched
on, the system remains in its current mode.

Figure 1 shows a partially completed state transition diagram that represents the
operation of the security system. Three of the states are labelled (X) to (Z) and events
are labelled (A) to (I).

Figure 1




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Complete Table 1 by filling in the unshaded cells with the correct labels from
Figure 1. You should write:

• which labels, (X) to (Z), represent which state
• which labels (A) to (I) represent which event(s).

Some of the events will be assigned more than one label.

Each label must only be used once.

Table 1

Event / State Label(s): (A) to (I), (X) to (Z)

Alarm bell ringing mode

Alert mode

Detect movement

Enter correct code

Enter incorrect code

Sensing mode

Switch on

10 second delay elapsed



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



Turn over for the next question




Turn over ►
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0 2 The algorithm, represented using pseudo-code in Figure 2, describes a method to
rearrange four numbers in a data structure.

Figure 2

Numbers[0] ← 45
Numbers[1] ← 19
Numbers[2] ← 62
Numbers[3] ← 12
FOR X ← 1 TO 3
Y ← X - 1
N ← Numbers[X]
WHILE Y > -1 AND N < Numbers[Y]
Numbers[Y + 1] ← Numbers[Y]
Y ← Y - 1
ENDWHILE
Numbers[Y + 1] ← N
ENDFOR

Complete Table 2 by hand-tracing the algorithm in Figure 2.

You may not need to use all the rows in Table 2.

The first row of Table 2 has already been completed for you.




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