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Edexcel GCSE Computer Science (1CP2) Exam Questions

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4 questions · 11 marks

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1Multiple choice1 markCharacter Sets Swap Remove

ASCII is a character set used for representing text.

Identify the number of bits used to encode each character in ASCII.

[1 mark]
  • A6
  • B7
  • C8
  • D16
Mark scheme
  • B 7 (1)
  • The only correct answer is B. The correct answer is 7 bits.
  • A is not correct because 6 bits give only 64 different characters
  • C is not correct because 8 bits are used by extended ASCII to give 256 characters
  • D is not correct because 16 bits give 65 536 different characters, which is far more than the 128 in ASCII
Example answers and how they were marked
Full marks1/1

B 7

Why: B is the only correct answer: each ASCII character is encoded using 7 bits (1).

No marks0/1

C 8

Why: Near miss scoring 0: 8 bits is extended ASCII, and the scheme's C line says extended ASCII, not ASCII, is not the answer.

No marks0/1

A 6

Why: Misconception scoring 0: 6 bits give only 64 different characters, so it cannot be ASCII.

2Explain2 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.

3Calculate2 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 patternShift8-bit binary result
1000 0001Logical 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.

4Discuss6 marksTranslators Swap Remove

A company writes a photo editing program in a high-level language. The company will sell the finished program to customers. Each customer will install the program on their own computer and run it many times.

Discuss whether the company should use a compiler or an interpreter to translate the program before it is sold.

Your answer should include:

  • the output of each type of translator
  • whether the program has to be translated each time it is run
  • what the customer needs on their computer to run the program.
[6 marks]
Mark scheme

Indicative content

The output of each type of translator

  • A compiler translates the whole program in one go and produces object code.
  • The object code is saved as an executable file, which is already in machine code so the processor can run it directly.
  • An interpreter does not produce object code, so no translated file exists for the company to save and sell.
  • An interpreter translates one line at a time and executes it immediately, but that translation is not kept.

Whether the program has to be translated each time it is run

  • Compiled code is translated once, so the executable can be run as many times as the customer likes without being translated again.
  • If the source code is edited, the whole program has to be compiled again to produce a new executable.
  • An interpreted program is translated again every time it is run, so a customer who runs the program often waits for translation at every run.
  • An executable runs faster than interpreted code because it is already in machine code.

What the customer needs on their computer to run the program

  • A customer who installs the executable needs no compiler on their computer, so the program will run straight away.
  • If the company supplied the source code instead, the customer would need an interpreter installed, and it would have to be an interpreter for their type of computer.
  • A customer given only the executable does not have the source code, so cannot change the program.

Conclusion

  • A compiler is the better choice for this company, because the executable can be sold and the customer runs it without it being translated again and without being given the source code.
  • Using an interpreter would mean supplying the source code to customers and translating the program on every run.

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)

Level 3 responses must cover all three bullets for this company's program, including translating once rather than on every run, and reach a conclusion.

Do not accept 'a compiler fixes errors' (a compiler reports syntax errors at the end of translation, it does not fix them) or 'a compiler is easier to use' with no link to output, translation or the customer. Do not accept answers about translating to assembly language.

Example answers and how they were marked
Full marks6/6

The company should use a compiler. A compiler translates the whole program in one go and produces object code, which is saved as an executable file. This executable is already in machine code, so the customer's processor can run it directly. The program is translated only once, so a customer who runs the program many times does not wait for it to be translated again, and it runs faster than interpreted code would. An interpreter produces no object code, so the company would have nothing to sell as an executable. The customer would have to be given the source code and would need an interpreter installed on their computer, and the program would be translated again every time it was run.

Why: Level 3. Covers the output of both translators (executable from the compiler, no object code from the interpreter), the effect of translating once rather than on every run, and what the customer needs on their computer, all applied to the company selling the program, with a clear conclusion.

Some marks3/6

A compiler produces an executable file, which the company can save and sell to its customers. An interpreter does not produce an executable file, so the customer would need the source code and an interpreter installed on their computer to run the program. This means a compiler is better for the company, because customers can just run the file they are given.

Why: Level 2. Gives the output of both translators and links this to what the customer needs, with a conclusion, but never says the compiled program is translated once while an interpreted one is translated on every run, so the reasoning is not developed enough for Level 3.

No marks0/6

The company should use a compiler because it is easier to write programs with a compiler and it fixes the errors in the program before the customers get it.

Why: Level 0. No creditworthy point: 'easier to write programs' is not linked to the output, the translation each run or the customer, and 'fixes the errors' is a misconception, as the mark scheme's guidance says a compiler only reports errors at the end of translation.

Questions by topic

2.1 Binary

Build a paper on this topic 58
Adding Binary Numbers 6 questions Binary and Hexadecimal Basics 10 questions Binary Shifts 6 questions Binary to Denary Conversion 6 questions Binary to Hexadecimal Conversion 6 questions Denary to Binary Conversion 6 questions Denary to Hexadecimal Conversion 6 questions Denary to Negative Binary Conversion 6 questions Hexadecimal to Binary Conversion 6 questions

2.2 Data representation

Build a paper on this topic 56
Character Sets 18 questions Images 19 questions Sound 19 questions

2.3 Data storage and compression

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Compression 18 questions Units & Conversion 6 questions

3.1 Hardware

Build a paper on this topic 77
Embedded Systems 17 questions Fetch Decode Execute Cycle 15 questions Primary Memory 15 questions Secondary Memory 15 questions Stored Program Computers 15 questions

3.2 Software

Build a paper on this topic 124
File Management 18 questions Memory Management 16 questions Peripheral Management 11 questions Process Management 12 questions Purpose & Function of Operating Systems 17 questions Software Basics 13 questions User Management 18 questions Utility Software 19 questions

3.3 Programming languages

Build a paper on this topic 37
Low and High Level Languages 19 questions Translators 18 questions

4.1 Networks

Build a paper on this topic 138
Addressing 16 questions LANs & WANs 16 questions Network Speed 5 questions Packet Switching 16 questions Protocols & Layers 17 questions The Internet 16 questions Topologies 17 questions Wired Connections 17 questions Wireless Connections 18 questions

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