AMD-K6-2E/400AFR AMD [Advanced Micro Devices], AMD-K6-2E/400AFR Datasheet - Page 70

• Manufacturer Part Number: AMD-K6-2E/400AFR
• Manufacturer: AMD [Advanced Micro Devices]

AMD-K6™-2E Processor Data Sheet
Figure 46. Page Table Entry (PTE)
3.5
52
Symbol
31
PCD
PWT
U/S
W/R
P
AVL
D
A
Available to Software
Reserved
Dirty
Accessed
Page Cache Disable
Page Writethrough
User/Supervisor
Write/Read
Present (valid)
Description
Descriptors and Gates
Physical Page Base Address
There are various types of structures and registers in the x86
architecture that define, protect, and isolate code segments,
data segments, task state segments, and gates. These structures
are called descriptors.
The application segment descriptor is used to point to either a
data or code segment. Figure 47 on page 53 shows the
application segment descriptor format. Table 9 contains
information describing the memory segment type to which
the descriptor points.
The system segment descriptor is used to point to a task state
segment, a call gate, or a local descriptor table. Figure 48 on
page 54 shows the system segment descriptor format. Table
10 contains information describing the type of segment or
gate to which the descriptor points.
The AMD-K6-2E processor uses gates to transfer control
between executable segments with different privilege
levels. Figure 49 on page 55 shows the format of the gate
descriptor types. Table 10 contains information describing
the type of segment or gate to which the descriptor points.
Bits
11–9
8–7
6
5
4
3
2
1
0
Preliminary Information
Software Environment
12
11
10
A
V
L
9
8
7
D
6
5
A
D
4
P
C
W
3
P
T
22529B/0—January 2000
2
U
S
/
W
1
R
/
P
0
Chapter 3