Siemens Simatic box pc 627b Operating Instructions Manual page 150

Detailed descriptions
16.4 BIOS Setup
The "Memory Cache" field
The following context menu appears when you select the option "Memory cache" in the main
menu:
Figure 16-5
The cache is a high-speed memory buffer between the CPU and memory (DRAM).
Repeated memory access operations are executed in the faster cache, and not in the main
memory, provided the feature is enabled. In some cases it may be necessary to disable the
cache for certain types of hardware and software because intentional program runtimes or
delay times may be prevented by the fast cache.
[Disabled]
[Write Through]
[Write Back]
16-32
"Memory Cache" field
Cache is disabled
Write access is not concluded until the entry has been made in main
memory
Write access is concluded immediately, the entry in main memory takes
place in the background (default)
Operating Instructions, Release 05/2006, A5E00362052-03
SIMATIC Box PC 627