a technique according to the invention enables a single bios to support processors with or without 64 - bit extensions efficiently . the bios creates a data structure having entries that correspond to elements stored in a state save area . the state save area elements themselves may be located at different addresses depending on whether or not the host processor includes 64 - bit extensions . but the corresponding entries in the data structure are located at the same offsets within the data structure in either case . during execution of an smi handler routine , the bios accesses the data structure whenever it needs to access elements of the state save area .