                               The EAX Register

Called the Accumulator.


Graphical Breakdown:

      [       16 bits       |    8 bits    |   8 bits    ]
                                   AH            AL
                                          AX
                           EAX

EAX is a 32 bit register that is broken down into:
AX - The Low 16 bit half
AH - High 8 Bits of AX
AL - Low 8 Bits of AX

EAX register is available from the 80386+.  AX/AH/AL are available
on all 80x86 processors.

A lot of instructions will run a little bit faster when paired
with this regster, but with the speed of the Pentium+ processors
this speed is hardly even noticed.  Another reason to pair with 
this register is some instructions, using this register the opcode
will be smaller (Less Bytes), usually by a byte or two. Other 
instructions such as LODS* and STOS* (where * = D, W, or B) (to name
two) take EAX/AX/AL as an implied operand.  Another example
would be the MUL and DIV instructions.

Other Information:


On startup in a .COM in real mode:

EAX = ????
AX = 0
AH = 0
AL = 0

(These values should NOT be used in general programming.  But, if you are
 coding for optimization and the application does not really matter that 
 much, in DOS you can almost count on these values.  Although, I wouldn't
 be tring to run them on DOS EMUs like OS/2, which the startup values
 may be differnt.  A lot of demo coders count on these values in making
 their demos a little smaller, although it is a portability issue if they
 will run on all systems.)
