Computer XP system maximum support for large memory

computer XP system maximum support for how much memory?
How much memory is supported depends on the number of bits in the operating system. It depends on whether it is 32 or 64. 32-bit and 64-bit hardware are not compatible with each other. The 32-bit XP system only supports 3.2G physical memory, and the system does not recognize it. 64-bit can use up to 128G of physical memory and 16TB of virtual memory.
32-bit system can support 3.25G (except windows2003), that is to say, you can only display 3.25G memory on 4G memory. 64-bit systems can support 128G (XP also has a 64-bit version, but generally 32-bit, 64-bit XP is said to have no official Chinese version). However, Windows 7 and VISTA 32-bit systems can be modified to enable PAE support to 128G, which is the same as Windows 2003.
In theory, 32 bits = 2^32B = 4 * 2^30B = 4GB, so the 32-bit operating system has access to the 4GB range of addresses.
In practice, I have never seen any 32bit XP able to access 4GB of physical memory.
Theory and reality seem contradictory, but it is not. Note that "access to the 4GB range of addresses" does not mean that "4GB of memory can be supported"!
Detailed analysis:
32-bit operating system can access 4G space, but here 4G refers to the addressing space, and can not simply correspond to the memory, we often use this space as the memory size, Because memory is the main object of CPU addressing. In fact, the addressing of the operating system includes addressing in memory modules, graphics memory, sound card NICs, and other hardware interrupts, so 4GB is the sum of all device addresses that the operating system can handle. That is, the memory space is only a part of the addressing space.
The fundamental solution is to upgrade to a 64-bit operating system or use 2003.