Because the computer system may have the most malleable design, it may absorb the brunt of changes. The view of the code may be as HLL source-codeassembly code or mixture of both. Product families In many cases embedded system designs are not unique, and there are a variety of systems of various prices and capabilities forming a product family.
Because of these complexities, it is common for organizations to use a real-time operating system RTOSallowing the application programmers to concentrate on device functionality rather than operating system services, at least for large systems; smaller systems often cannot afford the overhead associated with a generic real-time system, due to limitations regarding memory size, performance, or battery life.
For example, if a component design is changed it can force changes in spare component inventory, maintenance test equipment, maintenance procedures, and maintenance training. They must often detect and react to faults in both the computing and surrounding electromechanical systems, and must manipulate application-specific user interface devices.
However, they may also use some more specific tools: In circuit debuggers or emulators see next section. Then ask the same people which CPU is used for the engine controller in their car and whether the CPU type influenced the purchasing decision.
At least, it's a Examples include aircraft navigation, reactor control systems, safety-critical chemical factory controls, train signals. Each example portrays a real system in current production, but has been slightly genericized to represent a broader cross-section of applications as well as protect proprietary interests.
Predicting the worst case may be difficult on complicated architectures, leading to overly pessimistic estimates erring on the side of caution. For low-volume or prototype embedded systems, general purpose computers may be adapted by limiting the programs or by replacing the operating system with a real-time operating system.
On the other hand, the latest computer design technologies may not have been adopted by many embedded system makers because they aren't necessary. An in-circuit emulator ICE replaces the microprocessor with a simulated equivalent, providing full control over all aspects of the microprocessor.