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MOTOROLA M68040 USER'S MANUAL 3- 13
31 9876543210
POINTER TABLE ADDRESS XXXXXUW UDT
ROOT TABLE DESCRIPTOR (ROOT LEVEL)
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PAGE TABLE ADDRESS XXXXUW UDT
4K POINTER TABLE DESCRIPTOR (POINTER LEVEL)
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PAGE TABLE ADDRESS X X X U W UDT
8K POINTER TABLE DESCRIPTOR (POINTER LEVEL)
Figure 3-11. Table Descriptor Formats
3.2.2.2 PAGE DESCRIPTORS. Figure 3-12 illustrates the page descriptors for both
4-Kbyte and 8-Kbyte page sizes. Refer to Section 4 Instruction and Data Caches for
details concerning caching page descriptors.
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PHYSICAL ADDRESS UR G U1 U0 S CM M U W PDT
4K PAGE DESCIPTOR (PAGE LEVEL)
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PHYSICAL ADDRESS UR UR G U1 U0 S CM M U W PDT
8K PAGE DESCRIPTOR (PAGE LEVEL)
31 210
DESCRIPTOR ADDRESS PDT
INDIRECT PAGE DESCRIPTOR (PAGE LEVEL)
Figure 3-12. Page Descriptor Formats
3.2.2.3 DESCRIPTOR FIELD DEFINITIONS. The field definitions for the table- and page-
level descriptors are listed in alphabetical order:
CM—Cache Mode
This field selects the cache mode and accesses serialization as follows:
00 = Cachable, Write-through
01 = Cachable, Copyback
10 = Noncachable, Serialized
11 = Noncachable
Section 4 Instruction and Data Caches provides detailed information on caching
modes, and Section 7 Bus Operation provides information on serialization.
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