Increase size of RAM 256 > 512MB WinCE6

Miran
I have bought aftermarket navigation from S100 series (Chinese
manufacturer) for my Passat. WINCE6.0 on this device is running over
processor Cortex A8 and it should have 512MB of RAM (specified by
manufacturer). But truly there is inside of device chipset K4H561638N-LCCC
– and this is actually chipset with 256MB of RAM. And also under WINCE
system properties I have found: Total memory: 256MB. I have changed this
256MB chipset with bigger 512MB chipset (K4H511638J-LCCC). After changing
this, device is running as before and under WINCE system properties is
still marked Total memory: 256MB. So, as I discover so far, I should set
somewhere in WINce new value of RAM but I’m only electronic engineer and
I’m not familiar with programming stuff in WinCE so good. So, can anyone
help me with that and advice dump electronic how to do this step by step?
Thanks. Miran