Mail Archives: djgpp/1997/07/26/09:02:28
. Okay, now what about the ModR/M byte? That one really confuses me. I
. really don't know much about it at all. I don't understand the function
. of the first two bits. The next three bits, to my understanding hold
. either a register (the first operand?), or another three bits of the
. opcode, is that right? And the last three bits, to my understanding,
. hold either another register (the second operand?) or something else
. (what?)?
Chapter Four of "The Art of Assembly Language" describes the
MOD-REG-R/M byte. Check it out at http://webster.ucr.edu.
Appendix D also contains an expanded instruction/opcode list
that you might find useful. Best to grab the PDF version...
Randy Hyde
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