To use these functions, you'll need a little background on the
        Extended Memory Specification.  First, the basics:

        XMS is the memory area defined as "anything above 1M," and blocks
        of memory that reside in the XMS are referred to as Extended
        Memory Blocks (EMB's).  Memory that resides between DOS 640K and
        the 1M mark are called Upper Memory Blocks (UMB's), and may or
        may not be supported by the XMS driver (Himem.sys does NOT support
        them).

        Because EMB's are above the 1M mark, you cannot access them as
        you would with normal memory.  This is because DOS pointers are
        20 bits in length, giving you an address space of 1,048,576 bytes,
        or roughly 1 Megabyte.  This is why the driver gives you a
        ``handle'' instead of a pointer when you allocate an EMB.  With
        this handle, you can ask the driver to copy memory below the
        640K mark into the EMB, and vice versa.

        So, that's what all this is about, now let's see how you can do
        it with the functions provided with this chapter.