A-level
COMPUTER SCIENCE
Paper 1
Wednesday 10 June 2026 Afternoon Time allowed: 2 hours 30 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.
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 (also at the top of 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 100.
• No extra time is allowed for printing and collating.
• The question paper is divided into four sections.
Advice
You are advised to allocate time to each section as follows:
Section A – 40 minutes; Section B – 20 minutes; Section C – 20 minutes; Section D – 70 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.
IB/G/Jun26/G4003/V8 7517/1
, 2
Section A
You are advised to spend no longer than 40 minutes on this section.
Enter your answers for Section A in your Electronic Answer Document.
You must save this document at regular intervals.
0 1 Figure 1 shows the transition function (represented as a state transition diagram) and
part of the tape for a Turing machine.
The current position of the read/write head is indicated by the * symbol.
Figure 1
0 1 . 1 What is the maximum size for the tape of a Turing machine?
[1 mark]
IB/G/Jun26/7517/1
, 3
0 1 . 2 Complete the unshaded cells of Table 1 to show the result of tracing the computation
of this Turing machine for the first 23 steps only.
Show the contents of the tape, the current position of the read/write head and the
current state as the input is processed.
The top row of the table shows the initial state, the initial position of the read/write
head and the starting contents of the tape.
Table 1
Current
Tape
state
– – – 1* 1 1 – S0
Copy the contents of the unshaded cells in Table 1 into the table in your Electronic
Answer Document.
[6 marks]
Question 1 continues on the next page
Turn over ►
IB/G/Jun26/7517/1
COMPUTER SCIENCE
Paper 1
Wednesday 10 June 2026 Afternoon Time allowed: 2 hours 30 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.
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 (also at the top of 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 100.
• No extra time is allowed for printing and collating.
• The question paper is divided into four sections.
Advice
You are advised to allocate time to each section as follows:
Section A – 40 minutes; Section B – 20 minutes; Section C – 20 minutes; Section D – 70 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.
IB/G/Jun26/G4003/V8 7517/1
, 2
Section A
You are advised to spend no longer than 40 minutes on this section.
Enter your answers for Section A in your Electronic Answer Document.
You must save this document at regular intervals.
0 1 Figure 1 shows the transition function (represented as a state transition diagram) and
part of the tape for a Turing machine.
The current position of the read/write head is indicated by the * symbol.
Figure 1
0 1 . 1 What is the maximum size for the tape of a Turing machine?
[1 mark]
IB/G/Jun26/7517/1
, 3
0 1 . 2 Complete the unshaded cells of Table 1 to show the result of tracing the computation
of this Turing machine for the first 23 steps only.
Show the contents of the tape, the current position of the read/write head and the
current state as the input is processed.
The top row of the table shows the initial state, the initial position of the read/write
head and the starting contents of the tape.
Table 1
Current
Tape
state
– – – 1* 1 1 – S0
Copy the contents of the unshaded cells in Table 1 into the table in your Electronic
Answer Document.
[6 marks]
Question 1 continues on the next page
Turn over ►
IB/G/Jun26/7517/1
