Abstract: A security system for a computer operating system comprising a processor (37) that is independent of the host CPU (13) for controlling access between the host CPU (13) and a security partition formed in the storage device (21) for storing the operating system. A program memory (41) that is independent of the computer memory and the storage device (21) unalterably stores and provides computer programs for operating the processor (37) in a manner so as to control access to the security partition in the storage device (21). All data access by the host CPU (13) to the data storage device (21) is blocked before initialization of the security system and is intercepted immediately after the initialization under the control of the processor (37). The processor (37) effects independent control of the host CPU (13) and configuration of the computer (11) to prevent unauthorised access to the security partition on the storage device (21) during the interception phase.

Abstract: A security system for a computer operating system comprising a processor (37) that is independent of the host CPU (13) for controlling access between the host CPU (13) and a security partition formed in the storage device (21) for storing the operating system. A program memory (41) that is independent of the computer memory and the storage device (21) unalterably stores and provides computer programs for operating the processor (37) in a manner so as to control access to the security partition in the storage device (21). All data access by the host CPU (13) to the data storage device (21) is blocked before initialisation of the security system and is intercepted immediately after the initialisation under the control of the processor (37). The processor (37) effects independent control of the host CPU (13) and configuration of the computer (11) to prevent unauthorised access to the security partition on the storage device (21) during the interception phase.