Instead, they access memory using one of three memory models:
In the Flat memory model, Memory appears to a program as a single, continuous address space This space is called a linear address space.
The flat memory model is also known as the unsegmented model.
The Real-address mode memory model is the memory model for the Intel 8086 processor. It is supported to provide compatibility with existing programs written to run on the Intel 8086 processor.
It's a very old model.
Documentation / Reference
- Vol1 - 3.3 - Memory Organization 3.3.1 - Memory model of Intel® 64 and IA-32 Architectures - Software Developer’s Manual - Combined Volumes: 1, 2A, 2B, 2C, 2D, 3A, 3B, 3C, 3D and 4.