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:
Jun. 03, 2003
Filed:
Nov. 23, 1999
Stephen H. Chan, Los Altos Hills, CA (US);
ZiLOG, Inc., San Jose, CA (US);
Abstract
The present invention provides for data flow enhancement in processor architectures having one or more caches by allowing DMA-type transfers to and from these caches. Specific examples allow such direct transfers between a peripheral logic device and the cache memory, or between either the main memory or a special memory and the cache memory. This is done by the processor reserving a portion of cache for the direct transfer, which is then carried out by a DMA-type controller. While this transfer is occurring, the processor is able to carry out other tasks and access the unreserved portion of cache in the normal manner. In the preferred embodiment, the transfer is performed by a cycle stealing technique. Once the transfer is complete, the reserved portion of the cache may be accessed by the processor. The size of the reservable portion may either be fixed or dynamically determined by the operating system based on factors such as task flow management and data transfer rates. In a preferred embodiment, the operating system works in concert with the cache organized into cache lines, assigning each cache line an address tag field, with particular values of the address tag indicating that a given cache line is part of the reserved portion of the cache.