The rapid evolution of x86 architecture led to the implementation of new computational features that greatly complicated the microprocessor software development environment. The differences between x86 processors of different vendors, or between one generation of processor and another from the same vendor, were radical enough that software was not immediately portable from platform to platform. It was difficult to develop operating systems, device drivers, and application software without determining the type of processor in a given system. To develop software to run on a variety of platforms, the detection of subtle differences between instruction set implementations and other features from one processor to the next became critical.