                               The ESP Register

Called the Stack Pointer.


Graphical Breakdown:

      [       16 bits       |         16 Bits      ]
                                        SP
                           ESP

ESP is a 32 bit register that is broken down into:
SP - The Low 16 bit half

ESP register is available from the 80386+.  SP is available
on all 80x86 processors.

The ESP/SP register is used to point to the stack's offset.  When a
PUSH instruction is executed, SS:[EIP/IP] is addressed as the location
to put the memory. It points to the "top" of the stack.


Other Information:


On startup in a .COM in real mode SP points to the stack.

