                               The EDX Register

Called the Data.


Graphical Breakdown:

      [       16 bits       |    8 bits    |   8 bits    ]
                                   DH            DL
                                          DX
                           EDX

EDX is a 32 bit register that is broken down into:
DX - The Low 16 bit half
DH - High 8 Bits of DX
dL - Low 8 Bits of DX

EDX register is available from the 80386+.  DX/DH/DL are available
on all 80x86 processors.

This is a general register and is used in accessing ports with the OUT
and IN instructions.

Other Information:


On startup in a .COM in real mode:

EDX = ????
DX = 3355  (D1Bh)
DH = 12    (Dh)
DL = 27    (1Bh)   

(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.)
