What for is the "Extension memory backup size" in the Device Configurator used?

FAQ #101623

 

Introduction
In the Device Configurator there is a parameter "Extension memory backup size":

Using this parameter the size of the memory for backing-up DBs in runtime (in IL with the instruction SYSWR K 3xxx) was configured for firmware versions before 1.16.27.

Usage before firmware 1.16.27
With firmware older than 1.16.27, configuring an "Extension Memory Backup Size" reduced the size of available program memory by the double amount of configured backup size.

Usage with firmware 1.16.27
Starting with firmware 1.16.27 the available "Extension Memory Backup Size" size is always 256 kByte, independent of the used system or the configured parameter in the Device Configurar. The available size for the user program is not changed by this configuration. Therefore the configuration can be set to "None" and the memory is still available.

Explanation
The explanation is that now the backup partition is no longer a "linear" partition but a file system.