Disclosed is a microprocessor based system with a dynamically selectable Operating System that is capable of providing unique operating systems based upon current hardware states without user intervention. The system will determine the current state of the system and select from a plurality of operating systems the best operating system to load. In normal operating conditions the system will select the most full-featured and robust operating system. If, for example, the system loses alternating-current power, the system will shutdown, reboot, and automatically select an operating system with very limited capabilities and limited power consumption to allow the system to retrieve important data from the cache and store the data to a data storage device.