Patent ID: 7124290

Claim:
A computer system including a mass storage unit, the mass storage unit comprising: a first portion which contains a first operating system; a second portion distinct from the first portion; wherein: the second portion stores the value of an address comprised in the first portion and at which a boot record of the first operating system is located; the first portion has a sub-portion containing a second operating system; the second portion further stores the value of another address comprised in the first portion and which is the address of a boot record of the second operating system, whereby the second operating system can be activated without the first operating system being active, wherein the second portion of the mass storage unit comprises a master boot record and a forbidden portion, said master boot record storing a table of addresses and a set of instructions for loading other portions than the master boot record so that the master boot record can be the first portion of the mass storage unit loaded in a remote access memory of the computer at the booting of the computer, said forbidden portion being distinct from the master boot record and not designated either partially or indirectly by way of the table of addresses of the master boot record, and wherein the forbidden portion includes a second table of addresses among which addresses one designates indirectly the boot record of the second operating system.