The QNX operating system is a distributed real-time operating system developed by QSSL (QNX Software Systems Ltd.) of Canada. It can run not only on hardware environments with CPUs such as Intel X86 and Pentium as the core, but also on those with CPUs like PowerPC and MIPS as the core. Complying with the basic POSIX standards and real-time standards, the QNX operating system enables convenient porting of its applications.
QNX is a commercial Unix-like real-time operating system that adheres to POSIX specifications, with its target market mainly focusing on embedded systems. It is likely one of the most successful microkernel operating systems.
QNX is a commercial Unix-like real-time operating system that complies with POSIX specifications, and its target market is primarily embedded systems [1]. Founded in 1980, QNX is a well-known embedded system developer in Canada.
QNX has an extremely wide range of applications, including: controlling the music and media functions of Porsche sports cars, the control systems of nuclear power plants and the U.S. Army's unmanned Crusher tanks [2], as well as RIM's BlackBerry PlayBook tablets.
A Multi-Tasking and Multi-User Operating System
First and foremost, QNX is a multi-tasking and multi-user operating system. It supports the simultaneous scheduling and execution of multiple tasks on a single computer; it also allows multiple users to share one computer, where these users can submit tasks to the system through multiple terminals and perform interactive operations with QNX. During its design and implementation, QNX followed the POSIX 1003.1 standard, making it highly similar to the UNIX operating system in many functions—it supports both simultaneous access by multiple users and simultaneous execution of multiple tasks. Therefore, it is a multi-tasking and multi-user operating system.
A Parallel Operating System
The standard RTOS version of QNX only provides support for single-processor systems; in addition, it also offers the Neutrino version, which supports multiple processors and symmetric multiprocessing (SMP).
A Distributed Operating System
The QNX operating system can couple multiple computers in a network. It enables any process on any computer to communicate with any process on any other computer, just like communicating with a local process; it also allows any process on any computer to use resources on any other computer, as if they were local resources. The only requirement is that the user has the corresponding permissions. In this way, users can distribute tasks across the network and assign them to any other computer for completion. However, the user's experience is no different from working on a centralized multi-tasking operating system.
The difference between a distributed operating system like QNX and a network operating system lies in that a network operating system is a loosely coupled software running on loosely coupled hardware, while a distributed operating system is a tightly coupled software. This type of operating system makes it easy to establish a high-availability mechanism for task sharing.
A Real-Time Operating System
A real-time system can complete the specified functions within a limited time and respond to external asynchronous events within a limited time. QNX is an ideal real-time operating system, as it provides all the essential elements required for a real-time operating system: multi-tasking, a priority-driven scheduling method based on the "earliest deadline first" principle, and fast context switching. For applications with different real-time requirements, QNX can arrange appropriate scheduling according to the user's needs, allowing various applications to run optimally in the QNX environment.
An Embedded Operating System
QNX is regarded as an embedded operating system because it has a very small kernel, i.e., it is a microkernel operating system. The kernel of QNX is generally only a few dozen kilobytes in size, and the entire operating system can have its required modules customized according to specific needs. The customized system occupies a small amount of space while still retaining the characteristics of real-time performance and multi-tasking. Therefore, the entire operating system is also flexible and scalable.
About QNX
