

























































Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
OCR A Level Computer Science H446/01 Computer systems QP&MS Summer 2025
Typology: Exams
1 / 65
This page cannot be seen from the preview
Don't miss anything!


























































Time allowed: 2 hours 30 minutes
You can use:
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
Oxford Cambridge and RSA
INFORMATION
© OCR 2025
© OCR 2025
(ii) Charlie will need to store a large collection of files containing high definition images and high definition videos that he will use during his course.
State a type of secondary storage device that Charlie could use and give a reason why.
Type of storage .................................................................................................................................
Reason..............................................................................................................................................
(c) In addition to the Central Processing Unit (CPU), Charlie will purchase a Graphical Processing Unit (GPU) that will be used to process and display the graphics in his games.
(i) Tick (✓) one box on each row to indicate if each statement is referring to a CPU or a GPU.
Statement CPU GPU
Suited to performing simple operations in parallel on larger data sets
Suited to performing complex operations on smaller data sets
(ii) State two benefits of using a GPU to process and display the graphics in computer games.
Benefit 1 ...........................................................................................................................................
Benefit 2 ...........................................................................................................................................
(d) Charlie will require an operating system that will allow him to have several applications open at the same time.
(i) State which type of operating system Charlie will need to install.
© OCR 2025^ Turn^ over
(ii) An operating system that Charlie is thinking about installing uses a multi-level feedback queue.
Describe how a multi-level feedback queue works.
(iii) An operating system manages and installs device drivers.
Explain why hardware devices require a device driver.
(e) Once Charlie has installed an operating system he will need to install utility software.
State two utilities that Charlie could install and state the purpose of each.
Utility 1 .............................................................................................................................................
Purpose ............................................................................................................................................
Utility 2 .............................................................................................................................................
Purpose ............................................................................................................................................
© OCR 2025^ Turn^ over
(iii) OCR Consultants can base the CPU around a RISC architecture or a CISC architecture.
Compare two differences between a RISC architecture and a CISC architecture.
Difference 1 ......................................................................................................................................
Difference 2 ......................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
.......................................................................................................................................................... [4]
(iv) Describe a benefit of making the CPU a multicore CPU.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [2]
© OCR 2025
**(b) *** The employees of the large company work remotely from home and use large databases that store a lot of sensitive data. They need to be able to use the databases to search and sort data quickly.
OCR Consultants is considering two approaches:
Discuss the benefits and drawbacks of each of these approaches.
You should include the following in your answer:
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
© OCR 2025
(a) (i) Convert the denary number 189 into an 8-bit binary number.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [1]
(ii) Convert the denary number 189 into a hexadecimal value.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [1]
(iii) Convert the hexadecimal value E4 into a denary number.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [1]
(b) Explain the effect that a right shift of three places will have on a positive binary number.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [2]
© OCR 2025^ Turn^ over
(c) Show the subtraction of these two floating point binary numbers.
Both numbers are stored in a normalised floating point format, using 6 bits for the mantissa and 4 for exponent.
You should show your result in the same format.
Show your working out.
Working space ..................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Final 6-bit mantissa .............................................
Final 4-bit exponen t ............................................. [6]
© OCR 2025^ Turn^ over
4 Kofi is a software engineer and has been asked to write some code using the Little Man Computer (LMC) instruction set.
(a) State the LMC command that would be used for each description given in the table.
Description LMC Command
Load the value stored in the memory address into the accumulator
Branch without checking the value in the accumulator
Store the value from the accumulator into a memory address
Branch if zero is in the accumulator
Branch if zero or a positive number is in the accumulator
[3]
(b) Kofi has been asked to write a program that inputs two numbers and then outputs the largest of the two numbers.
Write the code for this program using the LMC instruction set.
You can assume that the two numbers will always be different.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [4]
© OCR 2025
**(c) *** Kofi is working on a number of projects. These include:
Discuss which of these projects should be written in a high level programming language and which should be written in a low level language.
You should include the following in your answer:
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
© OCR 2025
5 This diagram shows the logic circuit for a half adder.
(a) Complete the truth table for this half adder circuit.
C (Out)
A B S C (Out)
(b) Describe the difference between a half adder circuit and a full adder circuit.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [2]
© OCR 2025^ Turn^ over
(c) The diagram below shows a partially completed logic circuit for a full adder.
The full adder circuit contains three inputs:
The full adder circuit contains two outputs:
Complete the logic circuit to represent a full adder.
C(in)
Sum
C(out)
© OCR 2025^ Turn^ over
6 DCC Software is a company that creates a wide range of software products for home computers. Its products include image, video and sound editing software.
(a) DCC Software makes significant use of software libraries.
Explain the benefits of using software libraries to create software.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [4]
(b) Once DCC Software has written a piece of software, they use translators to translate the programming code.
(i) The table shows different stages of code compilation labelled A , B , C and D.
A Lexical analysis
B Syntax analysis
C (^) Code generation
D Code optimisation
In each box write the letter of the stage that matches each description.
Converts the high level code into low level instructions
Examines the code and improves the efficiency of it without affecting the functionality
Removes comments and whitespace and then converts the high level code into tokens
Identifies syntax errors and creates an abstract syntax tree [4]
© OCR 2025
(ii) DCC Software is considering the benefits of both an interpreter and a compiler.
State two benefits of using an interpreter.
Benefit 1 ...........................................................................................................................................
..........................................................................................................................................................
Benefit 2 ...........................................................................................................................................
.......................................................................................................................................................... [2]
(iii) State two benefits of using a compiler.
Benefit 1 ...........................................................................................................................................
..........................................................................................................................................................
Benefit 2 ...........................................................................................................................................
.......................................................................................................................................................... [2]
(c) DCC software uses a database table called TblSoftware to store details about all of their products.
ProductID Name Type Price
DCC01 DCCPhotos Image £129.
DCC02 DCCDraw Image £119.
DCC03 DCCAnimate Image £99.
DCC04 DCCMovie Video £189.
DCC05 DCCEffects Video £99.
DCC06 DCCAudio Sound £119.
TblSoftware