Unisys Corporation

Brian Joseph Sassone

Laurence P Flora

Manoj Gujral

David Edgar Castle

A data processing system is comprised of: a system bus having a main memory coupled thereto; multiple high level cache memories, each of which has a first port coupled to said system bus and a second port coupled to a respective processor bus; and each processor bus being coupled through respective low level cache memories to respective digital computers. In the high level cache memories, data words are stored with respective tag bits which identify each data word as being stored in one of only four states which are shared, modified, invalid, or exclusive. In the low level cache memories, data words are stored with respective tag bits which identify each data word as being stored in only one of three states which are shared, modified or invalid.

Multi-bus data processing system in which all data words in high level cache memories have any one of four states and all data words in low level cache memories have any one of three states

Growing community of inventors

Los Gatos, CA, United States of America

Brian Joseph Sassone