Digital Electronics - Computers - Discussion

Because it can address only 2^32 addresses as it is a 32 bit processor.

On the Pentium processor, the 4GB ad-dress space is split into two regions: a large-space area (of, say, 2GB), and a small-space area, which makes up the remainder of the hardware address space. The small-space area is itself split into a number of small-space regions, each of which can hold a small address space. A process which is to run in a small address space is assigned a small-space number, identifying which of the small-space regions it is to use. The segmentation registers are then used to relocate the process's address space into that region. A "large" process is not relocated and has access to the whole large-space area. The number of small processes is limited to the number of small-space regions.

Pentium 4 processor i.e. 4GB.