A method of changing the operating system in a computer system by using an address offset mode (AOM) feature for the address space of a hard disk drive connected to the computer system. Initialization of the computer loads the first operating system (OS) from a user area in the disk drive address space....http://www.google.ca/patents/US6415383?utm_source=gb-gplus-sharePatent US6415383 - Address offset feature for a hard disk drive
