Abstract: A system and method for extending the functionality of a digital system is disclosed. The system includes a read-only memory (ROM) for storing an extendible control application, a processing unit for executing the code stored in ROM, an imaging device for capturing optical images and converting them to digital code, random-access memory (RAM) for providing working memory for the processing unit and storage for files and images, an input-output (I/O) device for receiving user input and communicating with a host computer to transfer images and files, and an optional removable memory for providing storage for images and a means for introducing extensions into the system. The ROM image includes a patch manager and function pointers which, together, permit the redirection of the program execution sequence. New pieces of code (extensions) can, through such redirection, be incorporated into the original, non-modifiable control application, to supplement or replace routines of the original control application.

Abstract: The present invention provides an interrupt register for handling interrupt requests received from external devices at a common interrupt terminal of a CPU. The invention provides inputs, outputs, and storage means as part of the interrupt register. The interrupt register inputs and outputs are used for communication with both the external devices and CPU to prevent mishandling of the interrupt requests.

Abstract: A system and method for recovering from a power failure in a digital camera comprises a power manager for detecting power failures, an interrupt handler for responsively incrementing a counter device, service routines which register to receive notification of the power failure, and a processor for evaluating the counter and providing notification of the power failure to the service routines which then assist the digital camera to recover from the power failure.