Basic types of os

The functional characteristics of operating systems (os) can be divided into three basic types of operating systems: batch operating systems, time-sharing operating systems and real-time operating systems.

Batch processing system: (User can use offline, batch processing, multi-program running) ( Recommended learning: PHP video tutorial)

Batch processing system, also known as batch processing operating system. Batch processing means that the user submits a batch of jobs to the operating system and then no longer intervenes, and the operating system controls them to run automatically. This kind of operating system that uses batch processing job technology is called a batch operating system. Batch processing operating systems are divided into single-channel batch processing systems and multi-channel batch processing systems. The batch operating system is not interactive. It is an operating system proposed to improve CPU utilization.

Single-channel batch processing system (single-channel, automatic, sequential): The system processes jobs in batches, but one job is always kept in the memory.

Multi-channel batch processing system (multi-channel, macro-parallel, micro-serial): allows multiple programs to enter the memory and run at the same time. That is, multiple programs are put into memory at the same time and allowed to run alternately in the CPU. They share various hardware and software resources in the system. When a program is suspended due to an I/O request, the CPU immediately switches to running another program. It does not use certain mechanisms to improve the bottleneck problem in a certain technical aspect. Instead, it makes each component of the system as "busy" as possible and spends very little time switching tasks, achieving parallel work between various components of the system, making Its overall efficiency per unit time is doubled.

Time-sharing system: (interactivity, multi-user simultaneity/multi-path, independence, timeliness)

Time-sharing system (time-sharing system ), the meaning of "time sharing": Time sharing refers to multiple users sharing the same computer. Multiple programs time-share hardware and software resources. A time-sharing operating system refers to connecting multiple terminals with monitors and keyboards to a host, allowing multiple users to use the computer interactively and share resources in the host through the host's terminal. A time-sharing operating system is a multi-user interactive operating system. Time-sharing operating systems are mainly divided into three categories: single-channel time-sharing operating systems, multi-channel time-sharing operating systems, and time-sharing operating systems with foreground and background. The time-sharing operating system divides the CPU time into several segments, called time slices. The operating system takes time slices as units and serves each end user in turn.

Real-time system: (timeliness, reliability)

A real-time system means that the correctness of the calculation depends not only on the logical correctness of the program, but also on the result The generated time, if the time constraints of the system are not met, a system error will occur.

The so-called "real-time" means "timely", and a real-time system means that the system can respond to requests for external events in a timely manner, complete the processing of the event within the specified time, and control all real-time tasks in a coordinated manner of operation.

The correctness of a real-time system (RTS) not only depends on the logical result of the system calculation, but also depends on the time when the result is generated. A real-time system is a system that can complete system functions and respond to external or internal, synchronous or asynchronous times within a specified or determined time. Therefore, a real-time system should have the ability to identify and process discrete events within a pre-defined time range; the system should be able to process and store the large amounts of data required to control the system.

Hard real-time system: If an action must occur absolutely at a specified moment (or a specified time range), it is called a hard real-time system. For example, the automatic flight control system of an aircraft must provide absolute guarantee that a specific action will be completed within a specified time.

Soft real-time system: If it can accept occasional violations of time regulations and does not cause any permanent damage, it is called a soft real-time system, such as aircraft reservation systems and bank management systems.

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