Siemens SIMATIC Field PG P4, Manual

Page: 76 / 144

Configuring the SIMATIC Field PG P4
5-8
SIMATIC Field PG P4 Manual
A5E00180080-04
“Memory Cache” Field
The following pop-up menu appears when you select the option “Memory cache” in
the main menu:
PhoenixBIOS Setup Utility
Item Specific Help
System Time:
ESC Exit
System Date:
Select Item
Select Menu
+ / –
Select
Change Values
Sub-Menu
F9
F10 Setup Defaults
Save and Exit
Diskette A: [ 1,44MB 3 1/2” ]
Primary Master [10056MB]
Primary Slave [None]
Memory Cache:
Boot Options
Keyboard Features
Hardware Options
System Memory:
Extended Memory:
Secondary Master [CD-ROM]
Secondary Slave [None]
[ 02/06/2003]
640 KB
128511 KB
Enter
Help
F1
Advanced Security Power Boot Version Exit Main
[ 15:35:32 ]
Controls caching of
system conventional
memory and memory
above one megabyte.
[ Write Back ]
Disabled
Write Through
Write Back
Fig. 5-4 “Memory Cache” Menu
A cache is a fast memory buffer between the CPU and main memory (DRAM).
Recurrent memory access operations are executed in the fast cache, instead of
main memory, if the function is enabled. In rare instances involving some hardware
and software combinations, it may be necessary to disable the cache because the
program runtimes or waits are too short on account of 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)