Intel Extended Memory 64 Technology (Intel EM64T) enables 64-bit computing on the server/workstation and desktop platforms when combined with supporting software. Intel EM64T improves performance by allowing the system to address more than 4 GB of both virtual and physical memory.
Technically speaking, EM64T offers to Intel processors what x86-64 offers to AMD processors. Ancient disagreements such as 3Dnow-vs-MMX still holds, but the rest should be exactly the same. It is supported by latest XEON processors.
Intel EM64T provides support for:
- 64-bit flat virtual address space
- 64-bit pointers
- 64-bit wide general purpose registers (16 - added R8-R15)
- 64-bit integer support
- Up to 1 tebibyte (TiB) of platform address space
Currently physical addresses are restricted to 40 bits, and linear addresses are restricted to 48 bits, sign-extended.