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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 693 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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3 questions · 6 marks

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1Describe2 marksMemory Management Swap Remove

An operating system keeps a record of the memory it has allocated to each program.

Describe how this record is used.

[2 marks]
Mark scheme

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

  • The start and end address/size of the block allocated to each program is recorded (1) so the operating system knows which areas of main memory are in use and which are free (1)
  • The record is checked before memory is allocated (1) so memory already in use is not given to another program/is not overwritten (1)
  • The record is searched for a free block that is large enough (1) so a newly loaded program is placed in a suitable area of main memory (1)
  • The record is updated when a program ends/closes (1) so the memory it was using is marked as free for other programs (1)

Allow the record to be called a memory map/memory table/allocation table.

A response that only says the operating system keeps a record/list of the memory each program is using, without saying what the record contains, earns 0 marks.

A response that states what the record contains, e.g. the addresses/the start and end address of each block, earns 1 mark even if it does not say how the record is used.

Do not accept responses about saving programs/files to secondary storage or about moving programs to virtual memory, as these are not uses of this record.

Example answers and how they were marked
Full marks2/2

The operating system records the start and end address of the block of memory given to each program so that it does not give the same memory to another program.

Why: The start and end address of each block is recorded (1) linked to memory already in use not being given to another program (1).

Some marks1/2

The operating system records the start and end address of the memory used by each program.

Why: States what the record contains (1), but does not develop how the record is used, so the second mark is not earned.

No marks0/2

The operating system saves the programs to the hard disk so there is enough memory for other programs.

Why: Describes moving programs to secondary storage rather than how the record of allocated memory is used; no creditworthy point is made.

2Explain2 marksProcess Management Swap Remove

A user opens a web browser.

Explain what the operating system does to get the browser's process ready to run.

[2 marks]
Mark scheme

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

  • A process is created for the program (1) so that its instructions can be loaded into RAM (1)
  • The process is put into the ready state (1) so that it can wait for the CPU to become available (1)
  • The operating system adds the process to a queue of ready processes (1) so the scheduler can choose it when the CPU is free (1)
  • The operating system allocates the resources the process needs (1) so that it can start running when it is given CPU time (1)

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

Allow 'main memory' for RAM.

Do not accept 'the browser is downloaded/loaded from the internet'.

Do not accept 'the program is run immediately on the CPU' without the ready step.

Example answers and how they were marked
Full marks2/2

It creates a process and loads the browser's instructions into RAM, then puts the process in the ready state to wait for CPU time.

Why: Linked point (1) and reason (1).

Some marks1/2

It moves the program into RAM.

Why: A correct point (1) but no linked reason about the process being made ready.

No marks0/2

It runs the program straight away on the CPU.

Why: This describes the running state, not making the process ready, so no credit.

3Explain2 marksPurpose & Function of Operating Systems Swap Remove

A computer can appear to run several programs at the same time.

Explain one reason why an operating system schedules the processes running on a computer.

[2 marks]
Mark scheme

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

  • The operating system decides which process will use the CPU next (1) so the processor is shared between processes/processes take turns (1)
  • The operating system allocates CPU time to each process/gives each process a small amount of time on the CPU (1) so multitasking can take place/several programs can appear to run at once (1)
  • The operating system manages the state of each process, e.g. ready/running/blocked (1) so a process waiting for input/blocked does not stop other processes running (1)
  • The operating system can terminate/end a process that has stopped responding (1) so it does not affect other processes/the computer keeps working (1)

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

Do not accept the idea that the CPU runs two or more processes at exactly the same time; multitasking shares CPU time.

Do not accept 'the OS shares the CPU' on its own without saying how/why, e.g. giving each process a turn/CPU time.

Do not accept 'it stops programs crashing' without a link to process management, e.g. ending a process that has stopped responding.

Do not accept 'it manages processes' without saying what the operating system does.

Example answers and how they were marked
Full marks2/2

It decides which process will run on the CPU next so several programs can share the processor and appear to run at once.

Why: Linked point (1) and reason (1): CPU scheduling and shared processor.

Some marks1/2

It gives each program a small amount of time on the CPU.

Why: Point (1) only; it does not give a linked reason such as allowing multitasking.

No marks0/2

The CPU runs all the programs at exactly the same time.

Why: Misconception: the CPU does not run processes at exactly the same time; no creditworthy point.

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