Can somebody explain what
mov byte [es:eax], dl
would mean in NASM x86 assembler?
Specifically the [es:eax] part.
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Ciro Santilli OurBigBook.com
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badpanda
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Possible duplicate of [What does "DS:\[40207A\]" mean in assembly?](http://stackoverflow.com/questions/3819699/what-does-ds40207a-mean-in-assembly) – Ciro Santilli OurBigBook.com Nov 09 '15 at 16:47
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The syntax of [es:eax] indicates an indirect move in which es:eax register combination contains an address and the byte stored in register dl will be stored at that address.
es is a segment register and eax is a general purpose register used in the address calculation. I assume this is a 16 bit address model so the combination of the segment register and the eax register provides the complete 32 bit address for a far pointer.
See this web page on basic instructions and addressing.
And this web page on effective addresses as well as this one on addresses.
Richard Chambers
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