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:
Jul. 17, 2001
Filed:
Sep. 15, 1998
Ming-Tsan Kao, Kaohsiung, TW;
Ming-Mao Chiang, Hsinchu, TW;
Ming-Fen Lin, Taipei, TW;
Won-Yih Lin, Taichung, TW;
Industrial Technology Research Institute, Hsinchu, TW;
Abstract
An apparatus and method for controlling an asynchronous dual port FIFO memory is provided. The asynchronous FIFO may operate at frequencies satisfying 0.5f,<f,<f,or 0.5f,<f,<f,, where f,is the write frequency if f,is the read frequency, or vice versa. A FIFO in accordance with the present invention comprises a dual port random access memory, a read pointer, a write pointer, a synchronization circuit and a status indicator. In the FIFO design, the read pointer indicating the read address is a simple sequential counter, and the write pointer indicating the write address is a Gray code counter. Gray code to sequential count converters are used to convert the Gray codes to sequential counts. The synchronization circuit synchronizes the write pointer and the read pointer using a read clock. A status indicator with simple circuits is provided to indicate if the FIFO is almost full or empty.