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. 07, 1977
Filed:
Oct. 16, 1975
Charles Hamman Divine, Thornton, CO (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
A read only memory (ROM) patching arrangement is disclosed for providing valid output information whenever defective ROM word locations containing invalid information are addressed. The disclosed arrangement, which includes a decoder comprising a plurality of small capacity PROMs, detects the receipt of each address word representing a defective location, temporarily inhibits the output of the ROM, and causes a small auxiliary memory to output valid information as a substitute for that in the defective ROM location. The patching capability of the auxiliary memory and the decoder PROMs is increased by extending n bits of each ROM address word to n inputs of the auxiliary memory as well as to n inputs of each decoder PROM. The remaining inputs of the decoder PROMs, taken collectively, each receive a different one of the remaining bits of each ROM address.