Describe the purpose of an interrupt in a computer system.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.

1. [4] Four from:
2. ∞ Used to attend to certain tasks/issues
3. ∞ Used to make sure that vital tasks are dealt with immediately
4. ∞ The interrupt/signal tells the CPU/processor (that its attention is required)
5. ∞ A signal that can be sent from a device (attached to the computer)
6. ∞ A signal that can be sent from software (installed on the computer)
7. ∞ The interrupt will cause the OS/current process to pause
8. ∞ The OS/CPU/ISR will service/handle the interrupt
9. ∞ They have different levels of priority
10. ∞ After the interrupt is serviced, the (previous) process is continued
11. ∞ It enables multi-tasking to be carried out on a computer
12. ∞ A valid example of an interrupt e.g. 'out of paper' message for a printer