What are the 4 basic characteristics of an operating system?

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 (hardware resources and information resources) in the system can be used by multiple concurrently executing 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 needs to be supported by related hardware, such as multi-pipeline or multi-processor hardware environments.

Asynchronousity 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.

The functions of a computer operating system include processor management, memory management, file management, device management. The development of operating systems has mainly experienced single-channel batch processing systems, multi-channel batch processing systems, time-sharing systems, real-time systems, network and distributed systems, and multi-machine systems.

Concurrency, sharing, virtuality, asynchronicity.

The basic characteristics of the operating system are as follows:

1. Concurrency:

It is the presence of multiple programs at the same time in a computer system, and from a macro point of view, these programs are advancing at the same time. On a single CPU, these concurrently executed programs are run alternately on the CPU.

Program concurrency is manifested in two ways: Concurrent execution between user programs and user programs. Concurrency between user programs and operating system programs.

2. Sharing:

Resource sharing is when an operating system program and multiple user programs share resources in a system.

3. Randomness:

Randomness means that the operating system is running in a random environment, and a device may make an interrupt request to the processor at any time, and the system has no way of knowing what the running program will do and when.

4. Virtual

It refers to the technological transformation of a physical entity into several logical counterparts. In the operating system, the implementation of virtualization is mainly through the use of time-sharing. Obviously, if n is the number of virtual logical devices corresponding to a physical device, the speed of the virtual device must be 1 n of the speed of the physical device.

5. Asynchronicity: i.e., uncertainty. Multiple runs of the same program and data may yield different results; There is also uncertainty about the running time and sequence of the program; It is difficult for external input requests and operational failures to occur at a time. These are all manifestations of uncertainty.

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.

The operating system (OS) is the management of all the hardware resources of a computer system, including software resources and data resources. control program operation; improve the human-machine interface; Provide support for other application software, etc., so that all the resources of the computer system can be used to the maximum extent, and provide users with a convenient, effective and friendly service interface.

The operating system is usually the layer of system software closest to the hardware, which transforms the hardware bare metal into a fully functional virtual machine, making the use and management of the computer system more convenient, the utilization of computer resources is more efficient, and the upper-layer applications can get more support than the functions provided by the hardware.

Features The operating system is a huge management and control program, which roughly includes five aspects of management functions: process and processor management, job management, storage management, device management, and file management. At present, the common operating systems on computers are DOS, OS 2, Unix, Xenix, Linux, Windows series, NetWare, etc.