At present, the most widely used embedded operating system in China is?????

1. Demand analysis.

The relevant system analyst has a preliminary understanding of the requirements from the user, and then uses the relevant tool software to list the major functional modules of the system to be developed, and what are the small functional modules of each large functional module.

The system analyst has an in-depth understanding and analysis of the requirements, and uses word or related tools to make a document of the functional requirements of the document system according to their own experience and needs. This document will clearly list the general functional modules of the system, what are the small functional modules of the large functional modules, and also list the relevant interfaces and interface functions.

The system analyst reconfirms the requirements to the user.

2. Outline design.

First of all, the developer needs to carry out the outline design of the software system, that is, the system design. The outline design needs to consider the design of the software system, including the basic processing process of the system, the organizational structure of the system, the division of modules, the allocation of functions, the interface design, the operation design, the data structure design and the error processing design, etc., so as to provide the basis for the detailed design of the software.

3. Detailed design.

In the detailed design, the main algorithms, data structures, class hierarchies and invocation relationships involved in the implementation of specific modules are described, and the design considerations of each program (each module or subroutine) at each level of the software system need to be explained for coding and testing. It should be ensured that the requirements of the software are fully distributed to the software as a whole.

4. Coding. In the software coding stage, the developer starts to write specific programs according to the design requirements for data structure, algorithm analysis and module implementation in the "Software System Detailed Design Report", and realizes the functions of each module respectively, so as to realize the requirements for the function, performance, interface, interface and other aspects of the target system.

5. Testing. Test the written system. It is handed over to the user to use, and the user confirms each function one by one after using it.

There are many kinds of software testing: according to the test execution, it can be divided into internal testing and external testing; According to the test scope, it can be divided into module test and overall joint commissioning; According to the test conditions, it can be divided into normal operation test and abnormal condition test; According to the input range of the test, it can be divided into full coverage test and sampling test.

6. Software delivery.

After the software test proves that the software meets the requirements, the software developer shall submit to the user the target installer, the data dictionary of the database, the user installation manual, the user guide, the demand report, the design report, the test report and other products agreed in the contract between the two parties.

7. Acceptance. User acceptance.

8. Maintenance. Modify the application in whole or in part according to changes in user needs or changes in the environment.

Common embedded systems.

linux、uclinux、wince、palmos、symbian、ecos、ucos-ii、vxworks、psos、nucleus、threadx 、rtems 、qnx、integrity、ose、c executive

A structure in which multiple organs that can perform one or several physiological functions are grouped together in a certain order is called a system.

The word system was created from the transliteration of the English system and enriched with its foreign connotation. System refers to the orderly arrangement and arrangement of scattered things to form a holistic whole.

In the theory of digital signal processing, people call the entity that can process and transform digital signals as a system. Since the system of processing digital signals is to process the signal at a specified time or time sequence, this system is regarded as discrete time, and can also be described by four methods: time-based language, **, formula, and waveform.

In the abstract, both systems and signals can be thought of as sequences. However, the system is the mechanism that processes the signal, which is different from the signal. People study systems, design systems, and use systems to process signals and serve humans.

In addition to the four descriptions above, there are symbols, unit impulse responses, difference equations, and graphs to describe the system.

Qian Xuesen, a well-known Chinese scholar, believes that a system is an organic whole with specific functions formed by the combination of several components that interact with each other and depend on each other, and this organic whole is a component of the larger system to which it belongs.

Several parts in motion, in the interconnection and interaction, form a whole with a certain definite function, which is called a system.