PROTECTED MODE OF 80386

All the capabilities of 80386 are available for utilization in its protected mode of operation. In protected mode, it can address 4 Gigabytes of physical memory and 64 Terabytes of virtual memory per task.The 80386 in protected mode supports all the software’s (programs) written for 80286 and 8086 to be executed under the control of memory management and protection abilities of 80386.The 80386 in protected mode supports all the software’s (programs) written for 80286 and 8086 to be executed under the control of memory management and protection abilities of 80386.In this mode, the contents of segment registers are used as selectors to address descriptors which contain the segment limit, base address and access rights byte of the segment. The effective address (offset) is added with segment base address to calculate linear address. This linear address is further used as physical address, if the paging unit is disabled, otherwise; the paging unit converts the linear address into physical address.The paging unit is a memory management unit enabled only in protected mode. The paging mechanism allows handling of large segments of memory in terms of pages of 4Kbytesize. The paging unit operates under the control of segmentation unit. The paging unit if enabled converts linear addresses into physical addresses, in protected mode.

“Be yourself; everyone else is already taken.” ― Oscar Wilde