LKBEN11149: Which general Purpose Registers are used in an x86 and AMD64 CPU and what are they used for?


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LKB | Created: 02/04/2020 | Version: 0 | Language: EN | Rating: 0 | Outdated: False | Marked for deletion: False

Author: Wim Peeters - Keskon GmbH & Co. KG


Symptom

You would like to know the registers and what they are used for on normal intel architecture

Cause

none

Solution

EAX     Accumulator for operands and results data.
EBX     Pointer to data in the DS segment.
ECX     Counter for string and loop operations.
EDX     I/O pointer.
EBP     Pointer to data on the stack (in the SS segment).
ESI     Pointer to data in the segment pointed to by the DS register; source pointer for string operations.
EDI     Pointer to data (or destination) in the segment pointed to by the ES register; destination pointer for string operations.
ESP     Stack pointer (in the SS segment).

The 16-Bit Segment Registers are:
CS     Code Segment
DS     Data Segment
SS     Stack Segment
ES     Data Segment
FS     Data Segment
GS     Data Segment

About the Author

Wim Peeters is electronics engineer with an additional master in IT and over 30 years of experience including time spent in support, development, consulting, training and database administration. Wim has worked with SQL Server since version 6.5. He has developed in C/C++, Java and C# on Windows and Linux in different European countries and different European languages. He writes knowledge base articles to solve IT problems and publishes them on the Lubby Knowledge Platform where he is one of the most important contributors and the main developer.

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