I would want to know to what refers the number that it indicates the dimension of the memory of the devices. If my phone have 200kb of midp memory, it means that I have 200kb for store my j2me application or it means that the runtime memory for every application is 200kb.
There are two kinds of memory: storing memory for midlets and runtime heap memory. You can check the value of free storing memory for midlets. Go to the Applications menu and select Memory (the label of that function may vary between devices). That value tells you how much free storing memory for midlets you do have.
The heap memory can't be seen from the applications menu. You can find such information for example from the Java Phones section of Forum Nokia Java pages.