The document outlines 9 key functions of an operating system:
1. Device management which determines which applications run and for how long.
2. User interface which allows users to access and command the computer through either text-based or graphical interfaces.
3. Memory management which allocates memory to different jobs.
4. Process management which determines which jobs will execute first using scheduling algorithms.
5. File management which stores and manages files for creation, editing, and deletion across storage devices.
6. Job scheduling which establishes priority systems and mechanisms to control work order.
7. Interpreter which interprets system commands and instructions.
8. Security which provides protection of files from unauthorized access.
9.