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:
Oct. 23, 1990
Filed:
Aug. 05, 1988
George D Green, College Park, MD (US);
William C Mullauer, Baltimore, MD (US);
Microcomputer Doctors, Inc., College Park, MD (US);
Abstract
A method and apparatus for testing the functionality and maximum operating speed of a dynamic random access memory (DRAM) chip includes a random sequencer circuit for generating a pseudo-random data bit pattern to be written into the cells of a DRAM chip. The apparatus includes a variable clock circuit which produces a continuously variable frequency clock signal to continuously increase the speed at which data is written into the DRAM. During read cycles of the DRAM, data read from the DRAM is compared with the pattern produced by the random sequencer in a comparator, and any non-correspondence between bits will activate an LED to indicate a failure of the chip. In this way, the maximum speed of the chip may be determined to isolate both defective and marginally damaged chips. The apparatus is operated as a stand-alone unit which does not require the use of any software or interfaced host microprocessor.