Abstract: A system and method for protecting an electrically-powered article, particularly a computer system such as a personal computer, from theft by rendering it effectively useless to anybody but the rightful user/owner. The personal computer includes a power disruption indicator (21) to which electrical power must be applied even when the computer is shut-down (switched off at switch 12). The continuous power is normally provided by means of a mains-supplied power unit (10). In the event of mains supply discontinuities longer than a predetermined short time period, as would be the case if the equipment is stolen, subsequent start-up of the computer is prevented until a theft protection password is provided by a potential user. A separate power source, such as a capacitor (20), is provided to power the power disruption indicator for shorter time periods, such as when moving the computer within premises, and thus obviate the need to enter the theft protection password upon such occasions.

Abstract: In a method and a device for preventing unauthorised access to a computer system comprising at least one processing unit (1) or like, a disk unit (3), a display (5), and a keyboard (7), use is made of a floppy disk (9). Information in the form of a personal identification code containing the name of an authorised user and an access code encrypted by means of a one-way encrypting function, and an authenticity code formed by a system access code and at least the personal identification code are recorded on the floppy disk.