AMD-K6-IIIE+550ACR AMD (ADVANCED MICRO DEVICES), AMD-K6-IIIE+550ACR Datasheet - Page 50

• 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
General-Purpose
Registers
Figure 7. EAX Register with 16-Bit and 8-Bit Name Components
28
31
The eight 32-bit x86 general-purpose registers are used to hold
integer data or memory pointers used by instructions. Table 2
contains a list of the general-purpose registers and the
functions for which they are used.
Table 2.
In order to support byte and word operations, EAX, EBX, ECX,
and EDX can also be used as 8-bit and 16-bit registers. The
shorter registers are overlaid on the longer ones. For example,
the name of the 16-bit version of EAX is AX (low 16 bits of
EAX) and the 8-bit names for AX are AH (high order bits) and
AL (low order bits). The same naming convention applies to
EBX, ECX, and EDX.
EDI, ESI, ESP, and EBP can be used as smaller 16-bit registers
called DI, SI, SP, and BP respectively, but these registers do not
have 8-bit versions. Figure 7 shows the EAX register with its
name components, and Table 3 on page 29 lists the doubleword
(32-bit) general-purpose registers and their corresponding word
(16-bit) and byte (8-bit) versions.
Register Function
EAX
EDX
EBX
ECX
ESP
EBP
EDI
ESI
Commonly used as an accumulator
Commonly used as a pointer
Commonly used for counting in loop operations
Commonly used to hold I/O information and to pass parameters
Commonly used as a destination pointer by the ES segment
Commonly used as a source pointer by the DS segment
Used to point to the stack segment
Used to point to data within the stack segment
General-Purpose Registers
Preliminary Information
Software Environment
16
EAX
15
AH
8
AX
7
23543A/0—September 2000
AL
Chapter 3
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