File management

Process control

Memory allocation

Email handling

Forcefully shut down a process

Notify the CPU of an error

Restart the operating system

Allow hardware or software to request CPU attention

Sleep a process

Replace the process’s memory with a new program

Terminate a process

Create a new process

open()

exit()

exec()

fork()

fork()

create()

exec()

open()

Requests from a running program to the operating system for a service

High-level application functions used to execute a program

Network requests made by an OS

Direct user input commands to control the OS

Running only one process at a time

Quickly switching between multiple processes

Using multiple processors

Allocating more memory to a single process

User mode and Kernel mode

Process mode and Thread mode

Multi-threading mode and Single-threading mode

Supervisor mode and Batch mode

Running user applications

Storing files permanently

Managing hardware resources

Compiling code

Multiple users execute processes simultaneously with exclusive access to the CPU

A system that switches rapidly between multiple processes to provide the illusion of parallel execution

A system where a single process controls all system resources

A system designed for a single user to execute multiple applications