By looking at intel volume of instructions, I found this:
1) 88 /r MOV r/m8,r8
2) 8A /r MOV r8,r/m8
When I write a line like this in NASM, and assemble it with the listing option:
mov al, bl
I get this in the listing:
88D8 mov al, bl
So obviously NASM chosed the first instruction of the two above, but isn't the second instruction an option two? if so, on what basis did NASM chosed the first?