Abstract: This invention relates to personal computer systems and, more particularly, to such a system having security features enabling control over access to data retained in such a system. The present invention protects a trusted personal computer system against a probing attack, in which an unauthorized user would attempt to overcome the security feature elements of the personal computer system by inserting some form of probe into an opening provided in the system enclosure for other, legitimate, purposes such as cooling air flow or removable media insertion. A plurality of security feature elements are mounted within the enclosure for selective activation to secure and non-secure states and are disposed at locations inaccessible to any unauthorized user of the personal computer system attempting to affect the operation of any one of the security feature elements by insertion of a probe through an opening.

Abstract: An information processing system comprises a processor, a first bus for conducting signals in accordance with a first bus protocol that does not support I/O address signals; a second bus for conducting signals in accordance with a second bus protocol that supports input/output (I/O) address signals; and a bridge circuit for coupling the first bus to the second bus. The processor includes a circuit for emitting address signals and an address type signal directed to a selected peripheral device. The bridge circuit comprises a filter for determining whether the address signal emitted by the processor corresponds to a peripheral device coupled to a bus subordinate to the bridge circuit; and a translation circuit, coupled to the filter, for translating signals in accordance with the first bus protocol to signals in accordance with the second bus protocol for transmission to the selected peripheral device.