Edexcel GCSE Computer Science (1CP2) exam questions

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6 questions · 19 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the bus that carries addresses in one direction only, from the CPU to main memory.

[1 mark]

AAddress bus
BControl bus
CData bus
DSystem bus

Mark scheme

A Address bus (1)
The only correct answer is A. The correct answer is address bus. Do not accept 'address' on its own.
B is not correct because the control bus carries control signals in both directions between the CPU and other components
C is not correct because the data bus carries data in both directions between the CPU and main memory
D is not correct because the system bus is the collection of all three buses

Example answers and how they were marked

Full marks1/1

A Address bus

Why: Correct option: the address bus carries addresses in one direction only, from the CPU to main memory (1).

No marks0/1

C Data bus

Why: The data bus carries data in both directions, so it is not the bus that carries addresses in one direction only from the CPU to main memory; no creditworthy point.

No marks0/1

B Control bus

Why: The control bus carries control signals in both directions, not addresses in one direction only; this is the common control/address bus confusion, so no mark.

2Short recall2 marksStored Program Computers Swap Remove

Computers use the von Neumann stored program concept.

Define the term stored program concept.

[2 marks]

Mark scheme

Award one mark for any of the following up to a maximum of two marks:

Program instructions are stored in main memory/RAM (1)
The data used by the program is stored in main memory/RAM (1)
The CPU fetches/reads instructions from main memory to execute them (1)
The program can be run without the instructions being input again (1)

Allow 'the program is stored in memory' for one mark.

Do not accept answers about programs being stored on secondary storage, such as a hard disk or USB memory stick.

Do not accept answers that only describe the von Neumann architecture (e.g. having a CPU and memory) without stating that instructions are stored in main memory.

Example answers and how they were marked

Full marks2/2

Both the program instructions and the data the program uses are held in the same main memory, and the CPU fetches these instructions from memory to execute them.

Why: Instructions stored in main memory (1) and the CPU fetches instructions from memory to execute them (1).

Some marks1/2

Program instructions are stored in main memory.

Why: Instructions stored in main memory (1). No second point about data being stored in the same memory or about the CPU fetching instructions.

No marks0/2

The program is saved on the hard disk so that it can be loaded into RAM when the user runs it.

Why: A near-miss about secondary storage, which the mark scheme says not to accept; the stored program concept is about instructions being held in main memory.

3Explain2 marksProtocols & Layers Swap Remove

Two computers exchange data over a network.

Explain why network protocols are needed for the two computers to communicate.

[2 marks]

Mark scheme

Award up to two marks for a linked explanation such as:

Devices (can) understand/interpret the data they receive (1) because they follow the same set of rules for communication (1)
Data is sent in an agreed format/structure (1) so the receiving device can interpret/understand it correctly (1)
Devices (can) connect/communicate successfully (1) because they agree how the data is transmitted, such as the type of signal used (1)
Errors (can) be detected/handled (1) because both devices follow the same rules for checking the data (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'so devices can talk/communicate with each other' or 'so they can understand each other' without saying they follow the same rules/agreed format.

Do not accept an answer that only states protocols are a set of rules, without saying what this allows (e.g. the data can be understood/interpreted).

Do not accept a faster connection/speed as a reason why protocols are needed.

Do not accept naming a protocol (e.g. TCP/IP, HTTP, Wi-Fi) without an explanation of why it is needed.

Do not accept a description of what a protocol does (e.g. 'TCP splits data into packets') without saying why this is needed.

Example answers and how they were marked

Full marks2/2

Devices can understand the data they receive (1) because they follow the same set of rules for communication (1).

Why: Linked point (1) and reason (1): following the same rules is what lets the devices understand the data.

Some marks1/2

Data is sent in an agreed format (1).

Why: Point (1) identified, but no linked reason saying what the agreed format achieves.

No marks0/2

Protocols are needed so the connection is faster (0) because more data can be sent at once.

Why: Speed is not a reason protocols are needed, so there is no creditworthy point or linked reason.

4Calculate2 marksBinary Shifts Swap Remove

Computers manipulate binary patterns.

Complete the table with the result of applying the shift to the binary pattern.

[2 marks]

Binary pattern	Shift	8-bit binary result
1000 0001	Logical shift right by 1

Mark scheme

Award one mark for each correct nibble in the correct order:

0100 (1)
0000 (1)

0 marks if the response is not 8-bit binary.

Example answers and how they were marked

Full marks2/2

0100 0000

Why: Every bit moves 1 place right, with 0s in from the left: both nibbles are correct (2).

Some marks1/2

0100 0001

Why: A slip in the last bit. The first nibble is correct (1); the second is not.

No marks0/2

0000 0010

Why: Shifts the bits the wrong way. Neither nibble is correct.

5Discuss6 marksPurpose & Function of Operating Systems Swap Remove

A home computer is used to stream music, edit a video and download files at the same time.

Discuss how the operating system manages the processes running on the computer.

Your answer should include:

how the CPU is shared between processes
the states a process can be in
how the operating system responds when a process needs attention

[6 marks]

Mark scheme

Indicative content

How the CPU is shared between processes

The operating system uses multitasking to give each process a short time slice on the CPU, so the music, video editor and download appear to run at the same time.
The operating system decides which ready process will run next, so one program cannot keep the CPU to itself.
The operating system can stop a running process and move it back to ready when its time slice ends, so all processes make progress.

The states a process can be in

When a program is opened, the operating system creates a process and moves its instructions into RAM so it is ready.
The operating system moves a ready process to running when the CPU is free.
A running process becomes blocked when it is waiting for input or data, such as the download waiting for data to arrive.
When the process finishes, the operating system terminates it and releases the resources it was using.

How the operating system responds when a process needs attention

An interrupt is a signal to the CPU that needs immediate attention, so the operating system suspends the current process and runs the interrupt handler.
A hardware interrupt could be a printer out of paper, and a software interrupt could be an error in a program.
After the interrupt has been handled, the operating system can return the interrupted process to the CPU.

Levels

Level 0 (0 marks): No rewardable content.
Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Additional guidance

Level 3 responses must cover at least two of scheduling, process states and interrupts.
A response that only states that the OS 'manages processes' or gives a program a turn, without expansion, is limited to Level 1.

Example answers and how they were marked

Full marks6/6

The OS uses multitasking to share the CPU. It gives each process, such as the music player and the video editor, a small time slice so they appear to run at the same time. It decides which ready process is next and how long it runs. When the video editor is opened, the OS creates a process and moves its instructions into RAM so it is ready; when the CPU is free it moves it to running. If the download is waiting for data, the OS marks it blocked so the CPU is not wasted. If the printer runs out of paper, a hardware interrupt tells the CPU to stop and run the interrupt handler; afterwards the OS returns to the process.

Why: Covers scheduling with time slices, process states (ready, running, blocked) and interrupts, with sustained application to the music, video editor and download. Level 3.

Some marks4/6

The operating system uses multitasking so the music and video editor can run at the same time. It gives each program a small amount of time on the CPU. When a program is opened it creates a process and puts it in RAM. If a process is waiting for input it is blocked.

Why: Covers CPU sharing and process states, with some application, but says nothing about interrupts. Level 2.

Some marks1/6

The operating system manages processes by giving each program a turn on the CPU. This stops the computer crashing when too many programs are open.

Why: Gives only a basic, undeveloped point about giving each program a turn, with no linkage or application. Level 1.

6Discuss6 marksLow and High Level Languages Swap Remove

A school computing club is creating a quiz game. The game will be written by students who are new to programming. It will store the names and scores of players in a list. The club wants to choose a language that helps the students finish the game quickly and with few errors.

Discuss the characteristics of a high-level programming language that make it suitable for writing the quiz game.

Your answer should include:

how easy the language is to learn, use and debug
the data structures it provides for storing the players' names and scores
the built-in functions and library routines it provides.

[6 marks]

Mark scheme

Indicative content

Ease of learning, use and debug

High-level language statements are written in English-like words and mathematical symbols, so the students can read the quiz game code and understand what each line does.
The language is easier to learn than a low-level language, so students who are new to programming can start writing the quiz game quickly.
Errors are easier to find and fix because the code is readable; for example, the students can check a line that updates a score against the rule they intended.
The students do not need to know how the processor carries out each statement, so they can concentrate on the quiz questions and rules.

Data structures

High-level languages provide lists or arrays, so the names and scores of all the players can be stored under one name and processed with a loop.
A record can store a player's name and score as one item; in some languages a dictionary or class can be used instead, which keeps related data together.
Using a data structure makes the code shorter and easier to understand than separate variables for every player's name and score.

Built-in functions and library routines

High-level languages provide built-in functions such as print and input, so the students can display a question and read a player's answer without writing the underlying code.
Library routines such as a random number generator can be used to choose quiz questions, saving the students time.
String-handling routines can check or compare a player's answer, so the students do not have to write these routines themselves.
Reusing tested routines reduces the amount of code the students write and can reduce errors in the quiz game.

Levels

Level 0 (0 marks): No rewardable content.
Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Additional guidance: Credit only points applied to the quiz game and the students; comparison with low-level languages is not required, but a correct contrast may support a point if it is applied. Do not award generic claims such as 'high-level programs run faster', 'work on any computer' or 'students do not need to learn syntax' unless they are justified for the quiz game.

Level 3 responses must cover all three bullet areas with linked reasoning that explains why the characteristic helps the students finish the game quickly with few errors; an answer covering only two bullet areas is limited to Level 2. Do not award the idea that high-level code is already machine code or is understood directly by the processor. Accept dictionaries or classes as equivalents of records.

Example answers and how they were marked

Full marks6/6

A high-level language is suitable for the quiz game because its statements use English-like words and mathematical symbols, so students who are new to programming can read the code and see what each part of the quiz does. This also makes the game easier to debug, because the students can compare a line that updates a player's score with the rule they intended. The language gives the students lists or arrays, so all the players' names and scores can be stored under one name, and a loop can then go through the list to display the results. A record, or a dictionary in Python, can keep one player's name and score together, which is clearer than using separate variables. The language also provides built-in functions and library routines such as input, print and a random number generator, so the students do not have to write these from scratch. They can use input to ask for a player's name and print to show the score, and a random number routine to choose a question. This lets the club spend its time on the quiz questions and rules, so the students can finish the game quickly with fewer errors.

Why: Covers all three bullet areas with linked reasoning: readable English-like statements and debugging, lists/records for names and scores, and built-in input/print/random routines, all applied to helping new students finish quickly with fewer errors. This meets Level 3.

Some marks3/6

High-level languages use English words, so the students can understand the code for the quiz game and find mistakes more easily. They provide lists or arrays, so the players' names and scores can be stored together, and a loop can be used to display the scores. This makes the game easier to write for students who are new to programming.

Why: Level 2, 3 marks: covers ease of learning/use and data structures with some application to the quiz game, but gives no built-in facilities and limited development of why this helps the club finish quickly, so it is not Level 3.

No marks0/6

High-level code is already machine code, so the computer can run the quiz game without a translator. The students do not need to learn any syntax.

Why: Contains the machine-code misconception and a generic claim that the scheme does not credit; no creditworthy point is made, so Level 0.

Edexcel GCSE Computer Science (1CP2) Exam Questions

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Practice paper

Questions by topic

2.1 Binary

2.2 Data representation

2.3 Data storage and compression

3.1 Hardware

3.2 Software

3.3 Programming languages

4.1 Networks

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