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Siemens SIMATIC PANEL PC 877 User Manual

Page 236

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Detailed descriptions

17.6 BIOS setup

SIMATIC Panel PC 877

17-44

Operating instructions, Release 07/2006, A5E00877780-01

"Memory cache" field

The following context menu appears when you select the option “Memory cache” in the main

menu:

Figure 17-5 "Memory Cache" field

The cache is a high-speed memory buffer between the CPU and memory (DRAM).

Repeated memory access operations are executed in the fast 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]

Cache is disabled

[Write Through]

Write access is not concluded until the entry has

been made in main memory

[Write Back]

Write access is concluded immediately, the entry

in main memory takes place in the background

(default)