Method and apparatus for providing full accessibility to instruction cache and microcode ROM
US6925591B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 21, 2004 |
| Grant date | Aug 2, 2005 |
| Priority date | — |
| Expiry date | May 21, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C29/16
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for providing full accessibility to on-chip instruction cache and microcode ROM are described. A dummy tag and a dummy instruction are written into a cache tag array and an instruction array, respectively, during a test mode. The dummy tag is concatenated with a predetermined set number and a predetermined word address to form a dummy address having a dummy tag field, a set field and a word address field. An instruction fetch is invoked using the dummy address. The instruction cache is accessed with the dummy address, and a cache miss is forced to occur. The dummy tag field of the dummy address is written into the tag array at a row specified by the predetermined set number, and the dummy instruction is written into the instruction array at the same row. Execution of the dummy instruction is suppressed. A read operation is performed in a similar manner, except in that case an instruction cache hit is forced to occur to cause data to be read from the instruction cache. Execution of the data read from the cache is suppressed. Microcode ROM is also read by invoking a dummy instruction fetch. The dummy instruction fetch causes data to be retrieved from a predeter…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.