FBA The Creator

Did somebody know how to know the full memory of the system. I explain me:
When I read the Memory panel, on my PPC (WM2003), I have the physical memory, for example 35 Mo, I also have the virtual memory, for example 24 Mo, and I have on top of the screen the main memory: 59 Mo.

I have also a trackbar that allow me to change the ratio between physical memory and virtual memory, but the main memory don't change (because it's the sum between physical and virtual memory).

I would like to read this main memory (59 in my sample).

When I use getmemorystatus(0) I obtain the physical memory value (35 Mo in my sample).
This value is changing if I move the trackbar.

I've tried to sum up getmemorysatus(0) and getmemorystatus(4), but it don't work (and getmemorystatus(4) don't change if I move the trackbar).

Could you help me to know the full main memory?

Thanks