Final answer:
A timer in a computer system is used by the operating system for various purposes such as managing processes, preemptive multitasking, and scheduling tasks.
Step-by-step explanation:
In a computer system, a timer is used by the operating system to perform various tasks and ensure the system runs efficiently. The timer helps the operating system manage processes by allocating specific time slots to each process, known as time slicing. This allows multiple processes to run concurrently and prevents one process from monopolizing the CPU.
The timer also helps with preemptive multitasking, where the operating system can interrupt a running process and switch to another process based on a predefined time interval. This ensures fair allocation of resources and prevents any single process from hogging system resources for too long.
Additionally, the timer is used for scheduling tasks such as background processes, system maintenance, and periodic checks. By setting a specific time interval, the operating system can execute these tasks at regular intervals, maintaining system stability and performance.