跳转到主内容
Knowledgebase
Home
Renesas Electronics China - Knowledgebase

(SH7751R) What is coherency?

Latest Updated:03/23/2009

Question:

What is coherency ?

Answer:

Coherency means that data is matched between cache and external memory.

For example, writing to external SDRAM is not performed if the cache is hit when the cache is used in copy back mode.

Unmatching of data between the cache and external SDRAM occurs because only writing to relevant entry of cache is performed and writing to external SDRAM is not performed.

Unmatching data of external SDRAM is transferred to external I/O when performing DMA transfer between external SDRAM and external I/O in a state of unmatching. Be sure to match data by purge, etc. before DMA transfer.

Suitable Products
SH7751R
SH7751
SH7750S
SH7750R