A computer with a single processor can run more than one program at the same time.
Describe how the operating system manages processes.
Mark scheme
Award up to two marks for a linked description such as:
- Gives each process a share/a small amount (time slice) of the CPU time (1) so that several processes can run and appear to run at the same time (1)
- Decides which process will use the CPU next, e.g. by priority (1) so that the most important process is run first (1)
- Keeps track of the state of each process (ready/running/blocked) (1) so that each process is moved to the state it needs to be in (1)
- Moves a process that is waiting for input/a resource (e.g. a printer) to blocked (1) so that another process can use the CPU (1)
Do not award a mark for stating only that the operating system runs/controls the programs.
Do not award a mark for describing multitasking in general, e.g. 'the operating system runs more than one program at once', without saying how the operating system manages the processes.
Do not accept responses about memory management (e.g. loading a program into RAM), the user interface or user management.
Accept 'processor' for CPU.
Example answers and how they were marked
The operating system gives each process a small amount of time to use the CPU so that lots of processes can run and it looks like they are running at the same time
Why: Linked point (1) - a small amount/time slice of CPU time for each process - and development (1) - so several processes can run at once.
The operating system decides which process will use the CPU next.
Why: Gives the point that the operating system chooses the next process (1) but no linked development about priority or the effect of this.
The operating system runs the program on the CPU.
Why: Only states that the operating system runs programs, which the mark scheme says is not awarded, so nothing is credited.