Edexcel GCSE Computer Science (1CP2) Exam Questions

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.

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

• The CPU can only execute one process at a time (1) so the operating system must decide which process runs next (1)
• Each process needs CPU time (1) so the operating system must share the CPU between processes (1)
• One process could use the CPU for too long (1) so the operating system must give other processes a turn (1)
• A process may be waiting for a resource or user input (1) so the operating system can run another process that is ready (1)
• The user wants to run more than one program (1) so the operating system must manage which process uses the CPU and when (1)

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

Allow 'program' for 'process'.

Do not accept 'to manage processes' / 'so processes are managed' without a reason.

Do not accept answers about managing files, memory or peripherals.

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.