What is an operating system, and what are the four basic perspectives?

An operating system is a computer program that manages the hardware and software resources of a computer.

The operating system handles basic tasks such as managing and configuring memory, prioritizing the supply and demand of system resources, controlling input and output devices, operating the network, and managing the file system. The operating system also provides an interface for users to interact with the system.

The main functions of the operating system are:

1. Process management, its work is mainly process scheduling, in the case of a single user and a single task, the processor is only exclusive to a task of a user, and the work of process management is very simple. However, in the case of multiple programs or multiple users, when organizing multiple jobs or tasks, it is necessary to solve the problems of processor scheduling, allocation and **.

2. Storage management is divided into several functions: storage allocation, storage sharing, storage protection, and storage expansion.

3. Device management has the following functions: device allocation, device transmission control, and device independence.

4. File management: file storage space management, directory management, file operation management, and file protection.

5. Job management is responsible for handling any requirements submitted by users.

Answer]: AA [Analysis] From the user's point of view, the operating system is the interface between the user and the computer.

There are four characteristics of a computer operating system: concurrent, shared, asynchronous, virtual.

1. Concurrency: refers to the occurrence of two or more events in the same time interval. The concurrency of an operating system refers to the fact that there are multiple running programs in a computer system at the same time, so it should have the ability to process and schedule multiple programs to execute at the same time.

2. Sharing: It means that the resources in the system (hardware resources and information resources) can be used by multiple concurrent programs, rather than being monopolized by one of them. There are two ways to share resources: mutually exclusive access and simultaneous access.

3. Asynchronous: In a multi-program environment, multiple programs are allowed to be executed concurrently, but due to limited resources, the execution of the process is not consistent to the end. It's about stopping, moving forward at an unpredictable pace, and that's the asynchronous nature of the process.

4. Virtuality: Virtuality is a management technology that turns a physical entity into a logical number of counterparts, or a physical entity into a logical counterpart. The purpose of adopting virtual technology is to provide users with an easy-to-use, convenient and efficient operating environment.

The parallelism of a computer operating system refers to the fact that a computer system has the characteristic that it can perform operations or operations at the same time, and complete two or more kinds of work at the same time. Parallelism requires the support of related hardware, such as multi-pipeline or Changqianji multi-processor hardware environment.

Asynchronicity causes the operating system to run in a random environment, which can lead to time-related errors in the process. However, as long as the operating environment is the same, the operating system must guarantee that the same result will be obtained by running the program multiple times.

Concurrency, sharing, virtuality, asynchronicity.

Concurrency: Refers to the occurrence of two or more events in the same time interval, which occur simultaneously at the macro level but alternately at the micro level. Parallel:

Refers to two or more events occurring at the same time. The concurrency of the operating system: refers to the "concurrent" running of multiple programs in a computer system, which are running simultaneously at the macro level and alternately at the micro level.

Operating system and program concurrency are born together. Our computer's CPU has single-core, dual-core, quad-core, octa-core! A single-core CPU can only run one program at a time, and each program can only be executed concurrently (using the CPU alternately)!

A multi-core CPU can execute multiple programs at the same time, and multiple programs can be executed in parallel (running at the same time). Sharing: Resource sharing, which means that the resources in the system can be used at the same time in multiple concurrently executing processes in memory.

By "simultaneous", we tend to be at the macro level, while at the micro level, these processes may alternately access resources (i.e., time-sharing). There are two ways to share resources: mutually exclusive sharing mode and simultaneous sharing mode.

Mutually exclusive sharing mode: Some resources in the system can be used by multiple processes, but only one process is allowed to access the resources in a time period. Simultaneous sharing method:

Some resources in the system allow them to be accessed "simultaneously" by multiple processes for a period of time. Concurrency and sharing are mutually existent. Virtual:

It refers to the transformation of a physical entity into several logical counterparts, the physical entity (the former) is actually there, and the logical counterpart (the latter) is felt by the user. Asynchronous: In a multi-program environment, multiple programs are allowed to be executed concurrently, but due to limited resources, the execution of the process is not managed to the end, but to move forward at an unpredictable speed of stop-and-go, which is the asynchronous nature of the process!

Only if the system has concurrency, it can lead to asynchronicity, and without concurrency and sharing, there is no virtual and asynchronous.

Operating system (operationsystem, OS) refers to the control and management of the hardware and software resources of the entire computer system, and the reasonable organization and scheduling of computer work and resource allocation, so as to provide users and other software with convenient interfaces and environments, it is the most basic system software in the computer system. Users can interact directly with the operating system, but in most cases through an application. Hardware refers to resources such as CPU, memory, and hard disks.