Importance

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Abstract

A method of protecting programs and data in computers against unauthorized access and modifications employs a programmable hardware circuit to monitor memory regions of a computer. The memory regions are divided into different access levels, and the circuit is programmed to permit access only to predetermined regions. If an unauthorized access is attempted by a program, an address corresponding to the program location initiating the unauthorized access is detected and the program is stopped. This ensures that the procedures for protecting the operating system cannot be circumvented to gain unauthorized access to data of any type. After programming of the circuit is completed, the programming cannot be changed except by actuation of a hardware switch or by re-starting the computer. Removal of the circuit will cause short circuits, thus making it impossible to shut the circuit off without being detected.

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First Claim