[Erwin0723]

how do I know the rest of the ram memory in my lumia 1520 or other wp 8.1 devices???

[N_LaRUE]

Have a read of this - Storage on my Windows Phone | Windows Phone How-to (United States)

[Erwin0723]

that's only for storage,and i know about that,but what i need now is how to check ram memory like android device with their task manager menu,so we can see how many ram are using by running app n program n how many are available

[MSARUL]

I think You can`t do that in WP

[Futra Hurairah Salleh]

Download Aerize Optimizer? But that just optimizes and/or clears the memory.

[neo158]

that's only for storage,and i know about that,but what i need now is how to check ram memory like android device with their task manager menu,so we can see how many ram are using by running app n program n how many are available

Try the Field Medic app in the store, one of the things it can do is display the specs of the device it's running on 😉