Windows RAM Limitation patch questions

[myidisbb]

AFAIK the limitations on the amount of RAM that an x86 Windows can see and use is not a limitation of the OS itself, but a hard-coded limit set by the developers for God-knows-why..

It's because computers use a binary system and so 32 bit system can only address 4,294,967,296 bits which is 4GB. So the system uses 4GB address space. Think of 4GB address space as addresses that map to 4GB locations on the memory module. But to access every physical device on the computer the cpu can only find them based on a predefined table of addresses that map to the hardware devices, like how a phone book matches addresses to people. So the top part of the availble 4GB address list is used to map to devices such as keyboard, gpu etc. which means that they cannot be mapped to memory locations else you would have a case where one address maps to multiple locations. This is why you lose about 700MB of ram space because the system maps the addresses for those memory locations to actually point to devices on your system.

A simple example of what I mean is like this. You have 2 tables of hex values, 00h address maps to 00h physical memory location, up to FFh address which maps to FFh physical memory location. But now on my system I need to access a keypad and I can only do this if I remap addresses FEh and FFh to point to my keypad device, therefore those 2 addresses no longer map to memory locations and therefore when my cpu calls those addresses it is to access my keypad instead and the physical memory locations remain unaffected.

i think you gave a very good answer that anyone should be able to understand. thank you