OS I, Lec2:System Structuree

1 System Structures
An operating system provides the environment within which programs are executed. OSs are organized along many different lines. These goals form the basis for choices among various algorithms and strategies.
We can view an operating system from several points. One view focuses on the services that the system provides; another, on the interface that it makes available to users and programmers; a third, on its components and their interconnections.
1.1 Operating-System Services
An operating system provides an environment for the execution of programs. It provides certain services to programs and to the users of those programs. The specific services provided, of course, differ from one operating system to another, but we can identify common classes. These operating-system services are provided for the convenience of the programmer, to make the programming task easier.
One set of operating-system services provides functions that are helpful to the user.
- User interface.
- Program execution
- I/O operations.
- File-system manipulation
- Communications.

- Error detection.

- Resource allocation.

- Accounting.

- Protection and security.