Characteristics and Functions of Operating Systems

Basic features of operating systems

1. Concurrency

• Parallelism: refers to two or more events occurring at the same time.

• Concurrency: refers to two or more events occurring within the same time interval.

• In a multi-programming environment, concurrency refers to the simultaneous running of multiple programs within a period of time at a macro level

• In a single-processor system, only one program can be executed at a time, and these programs are executed alternately at a micro level

2. Sharing

• Sharing means that the resources in the system can be used by multiple concurrently executed processes.

• Sharing mode:

• Mutually exclusive sharing: resources can only be used by one process at a time.

• Simultaneous access: resources can be accessed by multiple processes at the same time.

**Concurrency and sharing are the core features of the operating system, and the two are mutually dependent conditions for existence. **

3. Virtualization

• Virtualization refers to the conversion of a physical resource into multiple logical counterparts through technical means. For example, virtual memory technology expands physical memory into a larger logical memory

4. Asynchronous

• Usually the execution of a process is not "in one go", but runs in a "stop-and-go" manner

• The asynchronicity of the process is an important feature of the operating system

The role of the operating system

• As an interface between the user and the computer hardware system
• As a manager of computer system resources
• Used to expand the machine