The 386 introduced 32-bit protected mode, the only mode supported by RTTarget-32. The difference from 16-bit protected mode is that the size of segments is no longer limited to 64k; rather, a segment can be up to 4 gigabytes in size. Thus, a single segment can be used to address the complete address space.

Near pointers are 32-bit offsets which are also interpreted relative to a segment register. Far pointers consist of a 16-bit selector and a 32-bit offset for a total of 48 bits.

In 32-bit protected mode, the address space is still segmented. However, since all available memory can be addressed with a single segment, the CPU can be set up such that segmentation can (almost) be ignored by the programmer. All segment descriptors to be used are initialized to refer to a segment starting at linear address 0 and extend over the complete address space or at least to the highest address that the system needs to access. Such an environment is referred to as a flat memory model. RTTarget-32 (and Win32) use this flat memory model.

Left Protected Mode

16-Bit Protected Mode

Down Descriptors and Descriptor Tables