Undocumented OpCodes -- By Robert Collins

This page was last updated on 07/29/95.

Many years ago, I came across a pre-production Intel 80386 In-Circuit-Emulator (ICE). I didn't have much use for it, it was archaic, used a UNIX interface; only communicated via serial terminal; and only supported a 16 MHz 80386. Then one day, I desperately needed an 80386 ICE (all I had at the time was an 80486 ICE), and I thought I would hook it up, to see if I could get it working. Much to my surprise, it worked. My only complaint, was its user interface (terminal interface) was cumbersome, it was slow, it lacked features, and was obsolete. Other than that, it was great! So after I got used to it, I had some spare time, and I got this great idea to attempt to tackle one of my favorite problems -- searching for undocumented opcodes. Quickly I assembled some source code with reserved opcodes in it. Much to my dismay, it disassembled the opcodes, and displayed the list of their mnemonics. The opcodes contained in this file, are the culmination of that work. The mnemonics are those given by the ICE.

This opcodes file used to be in one piece. I broke it up so I could track what opcodes people are interested in.

Get description of        [AAM]        [AAD]        [UMOV]       [LOADALL]
                          [ICEBP]      [SALC]

Download this file -- OpCodes.ZIP
ftp://ftp.x86.org/pub/x86/dloads/OPCODES.ZIP

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