MC68LC040RC25A Datasheet, PDF (62/442 Pages) Freescale Semiconductor, Inc – M68040 Users Manual

Freescale Semiconductor, Inc.
31
POINTER TABLE ADDRESS
ROOT TABLE DESCRIPTOR (ROOT LEVEL)
31
PAGE TABLE ADDRESS
4K POINTER TABLE DESCRIPTOR (POINTER LEVEL)
31
PAGE TABLE ADDRESS
8K POINTER TABLE DESCRIPTOR (POINTER LEVEL)
9876543210
X X X X X U W UDT
876543210
X X X X U W UDT
76543210
X X X U W UDT
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.
31
PHYSICAL ADDRESS
4K PAGE DESCIPTOR (PAGE LEVEL)
31
PHYSICAL ADDRESS
8K PAGE DESCRIPTOR (PAGE LEVEL)
31
INDIRECT PAGE DESCRIPTOR (PAGE LEVEL)
12 11 10 9 8 7 6 5
UR G U1 U0 S CM
43210
M U W PDT
13 12 11 10 9 8 7 6 5
UR UR G U1 U0 S CM
43210
M U W PDT
DESCRIPTOR ADDRESS
210
PDT
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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M68040 USER'S MANUAL
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