The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 07, 1999
Filed:
Jan. 16, 1999
Bruce Ernest Whittaker, Mission Viejo, CA (US);
Unisys Corporation, Blue Bell, PA (US);
Abstract
A small first level cache and large second level cache support a central processor in accessing necessary data for processing. The second level cache holds tag address words each having two status bits V and R. The V bit indicates validity/invalidity status while the R bit informs the second level cache of the validity/invalidity status of the corresponding address in the first level cache. As a result of the status information between the two caches, the spy-snoop operation and invalidation operation cycles are minimized as to the use required of the processor bus, enabling higher efficiency processor operations. Utilization is made of a smart-fill algorithm which selects the address locations for placement of new data in a second level cache for a Write operation and after a Read-Miss by analyzing the status values (V,R) for each address in order to minimize the overwriting of valid cache data.