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:
Jan. 19, 1999
Filed:
Sep. 27, 1995
Kenneth A Dockser, San Jose, CA (US);
VLSI Technology, Inc., San Jose, CA (US);
Abstract
A data processing system includes a microprocessor, memory, and an instruction substitution filter. The microprocessor has separate data and instruction caches. The filter includes configuration memory that occupies memory mapped I/O space. Configuration data indicating instruction types to be deimplemented is entered into the filter during a boot sequence. Once configured, the filter substitutes call instructions for the deimplemented instructions. When executed, the call instructions activate a substitution routine that determines the address of the deimplemented instruction and then performs a data read of the unfiltered deimplemented instructions and then implements the function that the deimplemented function was intended to implement (but, due to microprocessor defects, does not). Accordingly, the present invention allows a microprocessor with defectively implemented instructions to be used as intended with minimal performance penalties.