US 4,685,056 A · Computer security device

Abstract

A computer security decide for discouraging or preventing unauthorized entry into computer systems and for preventing the unauthorized copying of proprietary computer software or data in a computer system is disclosed. The security device is based at least in part in hardware and comprises logic device means, such as a programmable logic array or a ROM, for recognizing a group of signals present on a bus indicative of unauthorized copying efforts, latch means for remembering the detection of unauthorized copying efforts, and switching device means for interrupting the flow of DC supply power to preselected components or memory locations within the computer system containing memory whose contents is to be protected to render said components or locations inaccessible. The various embodiments of the invention presented each monitor one or more buses for signals representing an unauthorized address, data or commands or sequence of addresses, data or commands indicative of either unauthorized entry into a computer system or unauthorized copying.

Claims18

Dependent claims

In a digital computer system having a central processing unit (CPU), at least one memory device that includes several contiguous memory locations individually definable by discrete addresses, and at least one bus forming at least part of a path for the parallel transmission of information between the CPU and memory device, a security device for preventing unauthorized access to preselected memory locations within the memory device, comprising:

logic device means external to said CPU and said memory device for recognizing a group of signals present on said bus associated with accessing at least one memory location which has been predefined as a memory location which will not intentionally be accessed during the execution of authorized programs by the CPU, and generating in response thereto a first signal;
latch means for generating and maintaining a second signal whenever the first signal has been received from said logic device means;
and
switching device means, connected to the memory device, for preventing further access to at least the preselected memory locations within the memory device when the second signal is received from said latch means.

1 more element

Dependencies are inferred from the claim text.

Computer security device

Life of this patent

Computer security device

Life of this patent

Abstract

Claims18