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'seg' assembly instruction in .s file

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# 1  
Old 10-11-2010
'seg' assembly instruction in .s file
Is this x86? I encountered this instruction and can't seem to find any info on what it does anywhere. Any ideas? This is how it appears:

seg es
# 2  
Old 10-11-2010
It's probably a definition or macro, not an instruction. There's dozens of assemblers out there, which are you using?
# 3  
Old 10-12-2010
I use as86, which is an assembler for 8086..80386 processors
# 4  
Old 10-12-2010
From http://www.oldschoolhack.de/tutorials/87.txt:

Code:
Now lets go over the code in a bit more detail:

    MOV   AX, SEG OurString     ; Move the segment where OurString is located
    MOV   DS, AX                ; into AX, and now into DS

    MOV   DX, OFFSET OurString  ; Move the offset where OurString is located
    MOV   AH, 9h                ; Print string subfunction
    INT   21h                   ; Generate interrupt 21h

You'll notice we had to use AX to put the segment address of OurString in DS.
You will discover that you cannot refer to a segment register directly in
Assembler.  In last tute's PutPixel procedure, I moved the address of the VGA
into AX, and then into ES.

So it's not an instruction but something like a macro or operator.
# 5  
Old 10-13-2010
seg es is a directive that tells the assembler which segment...code/data etc. is affected by the instructions that follow it.
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