An Introduction to the eCos World · Cygwin--UNIX environment for Windows. · Insight--a graphical user interface (GUI) for GDB. · Source-Navigator--source code comprehension tool. 2 The Origins of eCos Initial design discussions for eCos began in the spring of 1997. The primary goal was to bring a cost-effective, high-quality embedded software solution to the marketplace. This new development would also complement the existing GNUPro tools, thereby expanding Cygnus' product offering. Another essential requirement was that eCos needed to be designed in such a way that a small resource footprint could be constructed. By working with different semiconductor companies, Cyg- nus was able to architect a real-time operating system (RTOS) that abstracted the hardware layer and was highly configurable. This enabled the RTOS to fit into many diverse embedded systems. The highly configurable nature of eCos also allowed companies to reduce time to market for em- bedded products. Reducing cost is always a concern in embedded systems. By using the open-source model, eCos was available with no initial costs. It could be downloaded and "test driven" free of charge. In addition to eliminating startup costs, another attractive cost-saving feature was that eCos had no backend charges--it had to be royalty-free. Developers have full access to the entire software source code, including the tools, which can be modified as necessary (see Appendix B, eCos License , for the eCos license). There are no up-front license fees for the eCos run-time source code or any of the associated tools; everything needed to set up a complete embedded software development environment can be accomplished for free. Developers do not have to contribute back any additional components or applications developed; however, they are required to contribute back modifications to the eCos code itself. These contri- butions help the open-source community develop a better product. Today, numerous companies are using eCos, and many successful products have been launched running eCos, including the Brother HL-2400 CeN network color laser printer, Delphi Communiport, and the Iomega Hip Zip Digital Audio Player. In a Word: Configurability In order to get an understanding of the eCos architecture, it is important to appreciate the component framework that makes up the eCos system. This component framework is specifically targeted at embedded systems and meeting the requirements associated in embedded design. Using this framework, an enormous amount of functionality for an application can be built from reusable soft- ware components or software building blocks. The eCos component framework has been designed to control components to minimize memory use, allow users to control timing behavior to meet real- time requirements, and use usual programming languages (e.g., C, C++, and assembly for certain implementations in the Hardware Abstraction Layer [HAL]). Most embedded software today provides more functionality than what might actually be needed for a particular application. Often, extra code is included in a software system that gives generic support for functionality that embedded developers are not concerned with and is not needed. This extra code makes the software unnecessarily more complex. Furthermore, the more code, the greater the chance of something going wrong. An example would be a simple "Hello World" program. With most RTOSes, full support for mutexes, task switching, and other features would be included, even though it is not necessary for such a simplistic application. eCos gives the developer ultimate control over run-time components where functionality that is not needed can easily be removed. eCos can be scaled from a few hundred bytes up to hundreds of kilobytes when features such as networking stacks are included and third-party contributions such as Web servers are used.