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The Unabridged Pentium 4 IA32 Processor Genealogy by Bob Colwell, Tom Shanley

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Paging-Related Changes

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

Description

The WP ...

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