CPU 31xC and CPU 31x, Technical Data 
Manual, 01/2006 Edition, A5E00105475-06 
4-1 
Memory concept 
4
4.1  4.1 Memory areas and retentivity 
4.1.1  CPU memory areas 
The three memory areas of your CPU: 
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Load memory 
The load memory is located on the SIMATIC Micro Memory Card (MMC). The size of the 
load memory corresponds exactly to the size of the SIMATIC Micro Memory Card. It is used 
to store code blocks, data blocks and system data (configuration, connections, module 
parameters, etc.). Blocks that are identified as non runtime-related are stored exclusively in 
load memory. You can also store all the configuration data for your project on the SIMATIC 
Micro Memory Card. 
 
 
Note 
User programs can only be downloaded and thus the CPU can only be used if the SIMATIC 
Micro Memory Card is inserted in the CPU.