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Index > Compiler Internals > out instruction

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badc0de02



Joined: 25 Nov 2013
Posts: 215
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badc0de02 01 Jan 2014, 21:11
why does allow me the out instruction only ax,al Question
at exsample:
Code:
out *,ax ;or
out *,al ;and
out *,123 ;h,o,d,b    

please help!
Post 01 Jan 2014, 21:11
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Walter



Joined: 26 Jan 2013
Posts: 156
Walter 01 Jan 2014, 21:59
OUT port,accum

The port can be an immediate value (<256),
but accum must be AL, AX, or EAX
Post 01 Jan 2014, 21:59
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 20621
Location: In your JS exploiting you and your system
revolution 02 Jan 2014, 05:00
badc0de02 wrote:
why does allow me the out instruction only ax,al Question
It is a limitation of the instruction set encoding. It is just how the x86 CPU does things with its non-orthogonal CISC instruction set.
Post 02 Jan 2014, 05:00
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