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. 29, 1986
Filed:
Dec. 27, 1983
Elbert A Cheek, Lexington, KY (US);
David R Thomas, Lexington, KY (US);
John D Zbrozek, Lexington, KY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Data from a patch memory (23) is substituted for that in a system ROM (9) by applying high order addresses to a standard PLA (19) having word lines (FIG. 3, 50a-50p). The address orders are separately applied to EXCLUSIVE OR circuits (27a-27g). The PLA (19) is personalized to activate line (21) at addresses to be substituted and to provide logical zeros to the EXCLUSIVE OR circuits (27a-27g) which change during the patch. Only one word line is required for each continuous patch, which vary in size on a patch-by-patch basis. The circuit is fast and efficient. It can be used for a wide variety of memory substitution applications.