The following paging-related changes were made to the 486 processor:
CR0[WP] (see Figure 19-2 on page 434) was added. Refer to “The Write Protect Feature” on page 450.
CR3[PCD] and CR3[PWT] were added. Refer to “Page Directory Caching” on page 451.
The PCD and PWT bits were added to each Page Directory Entry (PDE). Refer to “Page Table Caching” on page 452.
The PCD and PWT bits were added to each Page Table Entry (PTE). Refer to “Page Caching” on page 453.
The Page Size Extension (PSE) feature was added. This feature was first implemented in the Pentium® processor and was migrated backwards into the later versions of the 486. See “4MB Pages” on page 501 for a complete description.
The Write Protect Feature
The WP ...
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