In:
   AX     = 0102h
   BX     = new block size in paragraphs
   DX     = protected mode selector for memory block
Out:
   if successful:
     carry flag clear
   if failed:
     carry flag set
     AX     = DOS error code
     BX     = size of largest available block

Function 0101 - Free DOS Memory Block	Table of Content	Function 0200 - Get Real Mode Interrupt Vector