What Is Intel® Extended Memory 64 Technology?
Intel® Extended Memory 64 Technology (Intel® EM64T) is a technology that enhances server and workstation platforms with 64-bit addressability and related instructions. Since the last quarter of year 2006, all mobile, desktop, and server processors based on the Intel® Core™ Microarchitecture have supported the Intel® EM64T.
The table below lists 32-bit operating system, applications, and drivers and map it to its corresponding 64-bit mode.
| Legacy Mode | Compatibility Mode | 64-bit Mode |
| 32-bit operating system | 64-bit operating system | 64-bit operating system |
| 32-bit applications | 32-bit applications | 64-bit applications |
| 32-bit drivers | 64-bit drivers | 64-bit drivers |
| 4 GB address space | 64-bit flat virtual address space | |
| GPRs are 32-bit | GPRs are 64-bit |