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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 604 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.

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4 questions · 6 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the function of the control unit in the fetch-decode-execute cycle.

[1 mark]
  • ADecodes instructions
  • BPerforms arithmetic operations
  • CStores data and instructions
  • DTemporarily stores data being processed
Mark scheme
  • A Decodes instructions (1)
  • The only correct answer is A. The correct answer is Decodes instructions.
  • B is not correct because the arithmetic logic unit performs arithmetic operations
  • C is not correct because main memory stores data and instructions
  • D is not correct because registers temporarily store data being processed
Example answers and how they were marked
Full marks1/1

A Decodes instructions

Why: Correct option: the control unit decodes instructions during the fetch-decode-execute cycle (1).

No marks0/1

C Stores data and instructions

Why: Main memory stores data and instructions, not the control unit; this is a common distractor, so no mark.

No marks0/1

B Performs arithmetic operations

Why: Arithmetic operations are performed by the ALU, not the control unit; a common confusion between CPU components, so no mark.

2Multiple choice1 markCharacter Sets Swap Remove

Characters are encoded using 7-bit ASCII.

Identify the number of different characters that can be represented using 7-bit ASCII.

[1 mark]
  • A64
  • B127
  • C128
  • D256
Mark scheme
  • C 128 (1)
  • The only correct answer is C. The correct answer is 128.
  • A is not correct because 6 bits give only 64 different combinations
  • B is not correct because 127 is the largest 7-bit value, not the number of characters that 7 bits can represent
  • D is not correct because 256 characters need 8 bits, as used by 8-bit extended ASCII
Example answers and how they were marked
Full marks1/1

C 128

Why: Selects the only correct option (1): 7 bits give 2 to the power of 7, which is 128 different characters.

No marks0/1

D 256

Why: Near miss scoring 0: 256 is the number of characters that 8 bits give in extended ASCII, not 7-bit ASCII.

No marks0/1

B 127

Why: Misconception scoring 0, the off-by-one error the examiners' report describes: 127 is the largest 7-bit value, but 7 bits give 128 different characters.

3Short recall2 marksFetch Decode Execute Cycle Swap Remove

Von Neumann architecture uses the 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:

  • Instructions/programs are held/stored in main memory (RAM) (1)
  • The data the program uses is stored in the same memory as the instructions (1)
  • Instructions are fetched (one at a time) from main memory by the CPU (1)
  • Instructions (fetched from main memory) are decoded and executed (1)

Allow 'memory' for main memory/RAM.

Do not award two marks for a single statement that only says the program/instructions are stored in memory.

Do not accept answers that state the program is stored in secondary storage (such as a hard disk).

Example answers and how they were marked
Full marks2/2

The program instructions and the data it uses are both held in main memory, and the CPU fetches each instruction from main memory in turn to decode and execute it.

Why: Instructions/programs are held/stored in main memory (RAM) (1) and the data the program uses is stored in the same memory as the instructions (1). The fetching and executing points are also present but the maximum is two marks.

Some marks1/2

The instructions of a program are stored in main memory.

Why: Instructions/programs are held/stored in main memory (RAM) (1). Only one part of the definition is given, so one mark.

No marks0/2

The program is kept on the hard disk and is loaded when it is needed.

Why: The answer places the program in secondary storage, which the mark scheme says not to accept, so no creditworthy point is given.

4Calculate2 marksAdding Binary Numbers Swap Remove

Computers manipulate binary patterns.

Complete the table to show the result of the 8-bit binary addition.

[2 marks]
1286432168421
10010101
01001111
Mark scheme

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

  • 1110 (1)
  • 0100 (1)

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

Example answers and how they were marked
Full marks2/2

1110 0100

Why: 149 + 79 = 228, carrying where a column adds to 2: both nibbles are correct (2).

Some marks1/2

1110 0101

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

No marks0/2

1101 1111

Why: Writes 1 in every column with a 1 and never carries. Neither nibble is correct.

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