Fourth, several representative embedded operating system comparison
(1) VxWorks
WindRiver VxWorks operating system companies in the United States in 1983 the design and development of an embedded real-time operating systems (RTOS), Tornado embedded development is a key component of the environment. Good sustainable development capacity, high-performance core and user-friendly development environment, in the embedded real-time operating system fields occupy a place gradually. VxWorks can be cut with micro-kernel structure; efficient task management; flexible mandate communication; microsecond interrupt handling; support POSIX 1003.1b real-time extensions to support multiple physical media and standards, and complete TCP / IP network protocols.
But its high price. The operating system itself is proprietary, as well as the development environment, a higher than normal price, and typically costs more than 100,000 yuan to set up a development environment available for general application to every other charge royalties. General unreasonable for the source code, binary code only. Because they are dedicated operating system, the need for specialized technical staff in the development of technology and maintenance, software development and maintenance costs are very high. A limited number of hardware support.
(B) Windows CE
Windows CE and Windows series better compatibility, Windows CE is a big advantage of the promotion. WinCE3.0 which is a capacity for small, mobile, intelligent, 32, understand the modular equipment for real-time embedded operating system. For the establishment for handheld devices, wireless devices dynamic applications and services provides a feature-rich operating system platforms, it can in a variety of processor architecture on the run, and usually applies to those who have some memory space restrictions equipment. It is from the limited resources for the overall design of the platform's multi-threading, complete priority, multi-task operating system. Its modular design allows it to the Pocket PC controller for industrial users customized electronic equipment. The basic core operating system needs at least 200 KB of ROM. As the volume of embedded products, the costs have more stringent requirements, processor space should be part of the small as possible. System Disk and the number of available memory to the limit, and embedded operating system running on the limited memory (usually in the ROM or flash memory), and therefore on the size of the operating system, and put forward a high efficiency requirements . From a technical standpoint, as an embedded operating system Windows CE has a lot of shortcomings: no open-source code, application developers to be very difficult to achieve product customization; efficiency, power consumption performance is not outstanding, and in Windows Like the occupation of the system memory, using procedures huge; copyright licensing fees to companies is taken into account.
(3) Embedded Linux
This is the embedded operating system a new member of its greatest feature of the source code is open and follow the GPL agreement, in the past year or so become a hotspot, according to IDG forecasts Embedded Linux will account for the next two years embedded operating system share of 50 per cent.
Because of its open source code, it can be modified to meet their applications, and Chaxi also very easy. Comply with the GPL, the need for the application of each pay permit fees. A large number of applications available. Most of them follow the GPL, the open source and free of charge. Little can be modified for the user's own system. A large number of outstanding free development tools, and follow the GPL is the open-source. A large group of developers. Without specialized personnel, as long as understood Unix / Linux and C language can be. With the popularity of Linux in China, more and more such talents. Therefore, software development and maintenance costs low. Excellent networking capabilities, which is particularly important in the Internet era. Stability - this is Linux itself have a great advantage. Jinghan core operation for less resources, and is very suitable for embedded applications.
The large number of hardware support. Embedded Linux, and there is no essential difference between ordinary Linux, PC hardware used on virtually all embedded Linux support. Various hardware and driver source code can be for users to prepare their own proprietary hardware drivers have a great convenience.
In the embedded Linux operating system is a shortcoming of the Linux system to provide real-time performance need to add real-time software modules. These modules run the operating system kernel space is the realization of scheduling strategy, the hardware interrupt abnormal and part of the implementation process. As a result of these real-time software module is the core of the operating room, coding errors could undermine the entire operating system thereby affecting the reliability of the system, which will be for real-time applications is a very serious weakness.
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