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:
Nov. 06, 2007
Filed:
May. 30, 2003
John Lo, Fremont, CA (US);
John Lo, Fremont, CA (US);
Sun Microsystems Inc., Santa Clara, CA (US);
Abstract
A method and apparatus for facilitating the determination of a status of an asynchronous memory (e.g., how full or empty the memory is). A write pointer to the memory is maintained in a first clock domain; a read pointer is maintained in a second clock domain. The pointers are maintained in a non-binary code format promoting minimum bit transitions as the pointers increment (e.g., Gray code). Each pointer is transmitted to the other clock domain through synchronizers. Each synchronizer comprises multiple sets of D flip-flops. In each clock domain, the write pointer and read pointer values are converted to mathematically useful formats (e.g., binary), and their difference is calculated. The difference indicates how much space in the memory is or is not used, and may be compared to a non-zero threshold.