Hardware is expensive. Coding is expensive. Changes are expensive. Implementing software rapid prototyping for Electronic Control Unit (ECU) development can avoid these expenses and resulting delays by enabling changes to existing code to allow easy calibration, experimentation or testing before committing to production software.Software-centric prototyping has been around for many years. In the past, experts used a technique called ‘code patching’ to do what is now called rapid prototyping. Using this method, these coders were able to change existing programs. Even in early vehicle control systems, there were a few people with the expertise to manually view and study code to enable a change in existing code.ATI took the idea of manually trying to change a program a step further. ATI invented a method of patching in new code on the ECU without the need for the original source code, any knowledge of assembler or hex code, or predefined hooks. With ATI's patented No-Hooks, anyone can now “access” the code to add a change easily. All the information needed to perform No-Hooks can be garnered from files needed for calibration that are always provided with development ECUs. ATI's No-Hooks is that simple, but so unique that the process is patented.Today, all software rapid prototyping tools seem to imply that the tool does not need hooks and /or the original software code. This may only be considered true if hooks are provided or “built-in.” The real challenge arises when unanticipated needs appear - and they always do. With the complexity of control systems increasing exponentially, anticipating all future development needs or situational variables is impossible. The investment in a software rapid prototyping tool must be judged throughout the development process on its flexibility to avoid delays and roadblocks caused by missed “hooks” that inevitably result in expensive consequences.