AMD-K6-IIIE+550ACR AMD (ADVANCED MICRO DEVICES), AMD-K6-IIIE+550ACR Datasheet - Page 52

• Manufacturer Part Number: AMD-K6-IIIE+550ACR
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of AMD-K6-IIIE+550ACR

• Lead Free Status / RoHS Status: Not Compliant

AMD-K6™-IIIE+ Embedded Processor Data Sheet
Segment Registers
Figure 9. Segment Register
Segment Usage
30
The six 16-bit segment registers are used as pointers to areas
(segments) of memory. Table 4 lists the segment registers and
their functions. Figure 9 shows the format for all six segment
registers.
Table 4.
The operating system determines the type of memory model
that is implemented. The segment register usage is determined
by the operating system’s memory model. In a real mode
memory model, the segment register points to the base address
in memory.
In a protected mode memory model the segment register is
called a selector and it selects a segment descriptor in a
descriptor table. This descriptor contains a pointer to the base
of the segment, the limit of the segment, and various protection
attributes. For more information on descriptor formats, see
“Descriptors and Gates” on page 59. Figure 10 on page 31 shows
segment usage for Real mode and Protected mode memory
models.
Segment
Register
15
GS
CS
DS
ES
FS
SS
Segment Register Function
Code segment, where instructions are located
Data segment, where data is located
Data segment, where data is located
Data segment, where data is located
Data segment, where data is located
Stack segment
Segment Registers
Preliminary Information
Software Environment
0
23543A/0—September 2000
Chapter 3