05848435 is referenced by 51 patents and cites 29 patents.

An address protection circuit (APC) for cross-checking the integrity of requests to read or write an addressable system memory in a fault-tolerant computer system. In a check mode, the APC checks each address and a source identification code of each memory access request from an address source. The source identification code and current bus address are compared to a range of addresses stored in the APC. If the current bus address is within an "authorized" range, access to that range of locations in the memory is allowed to the address source. If a current memory access request is not authorized, the APC asserts an error signal which may be used to transfer control to a redundant subsystem. The APC contains a content-addressable memory element that can be initialized by a subsystem processor with address ranges and type of access (e.g., read or write) allowed for each source. To enter the setup mode, the APC must first be addressed to switch the APC from its check mode. Thereafter, only a single value in the APC can be changed by the processor. The APC then automatically reverts to its check mode. Further changes to values in the APC each require an explicit switch from the check mode to the setup mode.

Title
Address protection circuit and method for preventing access to unauthorized address rangers
Application Number
600512
Publication Number
5848435
Application Date
October 23, 1995
Publication Date
December 8, 1998
Inventor
Edde Tin Shek Tang
Boulder
CO, US
William Alexander Brant
Boulder
CO, US
Agent
Carol W Holland & Hart Burton Esq
William J Kubida Esq
Assignee
EMC Corporation
MA, US
IPC
G06F 12/14
View Original Source