Introduction

Embedded Computing Applications exist in a spectacular range of size and complexity for areas such as home automation to cell phones, automobiles, and industrial controllers. Most of these applications demand such functionality, performance, and reliability from the software that simple and direct assembly language programming of the processors is clearly ruled out. Moreover, as a distinguishing feature from general purpose computing, a large part of the computation is “real-time” or time constrained and also reactive or “external event-driven” since such systems generally interface strongly with the external environment through a variety of devices. Thus, an operating system is generally used. An operating system facilitates the development of an application program by making available a number of services, which, otherwise would have to be coded by the application program. The application programs “interface” with the hardware through the operating system services and functions. It is therefore important to understand the basic features of such operating systems, and this is what we will do in this seminar.

Real-time Operating Systems

A Real-Time OS (RTOS) is an OS with special features that make it suitable for building real-time computing applications also referred to as Real-Time Systems (RTS). Real-time operating systems (RTOSs) provide basic support for scheduling, resource management, synchronization, communication, and I/O like general purpose OSs (GPOSs) but also have 2 additional features for precise timing. RTOSs have evolved from being completely predictable and support safety-critical applications to those which support soft real-time applications. Soft and hard applications are dealt with later. Researchers have developed new paradigms and ideas that enhance the GPOSs to be more efficient and predictable. The current RTOS market includes many proprietary kernels for embedded systems like Atmega, composition-based kernels, real-time versions of popular OSs like Linux (Linux RT) and Windows NT (Windows CE). RTOSs are mainly developed for real-time systems (RTS). In an RTS, the correctness not only depends on the correctness of the logical result but also the result delivery time. An RTS is expected to respond in a timely, predictable way to unpredictable external stimuli.

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Diagrams and Results