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:
Nov. 25, 1997
Filed:
May. 14, 1996
Brian B Tucker, The Woodlands, TX (US);
Gary W Thome, Tomball, TX (US);
Compaq Computer Corporation, Houston, TX (US);
Abstract
Circuitry which corrects a problem in the 82424TX Cache and Dram Controller (CDC) from Intel with the addition of only minor circuitry which can be used externally or internally and which allows proper operation under all conditions. Combinatorial logic is provided to block the dirty bit provided by the dirty Static Random Access Memory (SRAM) when the processor is performing a noncacheable access as indicated by the Page Cache Disable (PCD) bit. In certain cases the PCD bit is ignored and the stored dirty bit is passed without blocking: when the AHOLD signal is asserted, indicating that an address snoop operation is occurring, and when the BOFF* signal is asserted, indicating that a cache flush or writeback operation is occurring. Thus, the dirty bit provided by the dirty SRAM when the processor is performing a non-cacheable access is selectively blocked in certain instances to ensure cache coherency.