25.1  WHAT AND WHERE

Robert Collins has make available an excellent article on Intel
Undocumented OpCodes.  Just set your web browser to:

    http://www.x86.org/secrets/OpCodes.html

25.2  EXTENDED FORMS OF AAM AND AAD INSTRUCTIONS

Mr. Collins describes extended forms these two instructions.  AAM is
ASCII Adjust after Multiplication, and ADD is ASCII Adjust before
Division.  These instructions are known as quick ways to divide and
multiply by ten, as these instructions normally assemble with 10 as the
default operand.   Using macros provided, any value from 0h to 0ffh can
be substituted.  These instructions are available on all x86 Intel
processors.

25.3  SALC - SET AL ON CARRY

Mr. Collins describes this instruction a C programmers dream instruction
for interfacing to assembly language procedures.  This instruction will
set the AL register to 00h or 0ffh depending on whether the carry flag
is clear or set, respectively.  This instruction is available on all x86
Intel processors.

25.4  ICE RELATED OPCODES

Mr. Collins describes several instructions that appear whose existence
makes debugging run-time code easier on the ICE debugger.  There are:
    ICEBP   - ICE Break Point
    UMOV    - User Move Data
    LOADALL - Loads the Entire CPU State

Contributor:  Raymond Moon, raymoon@moonware.dgsys.com
Last changed: 4 Nov 95

Some parts © 2009 Advameg, Inc.