Allocate DOS Memory Block


                 This function  will allocate a block of memory from the
                 DOS free  memory pool.   It  returns both the real mode
                 segment and one or more descriptors that can be used by
                 protected mode applications to access the block.

            To Call

                 AX = 0100h
                 BX = Number of paragraphs (16 byte blocks) desired

            Returns

                 If function was successful:
                 Carry flag is clear.
                 AX = Initial real mode segment of allocated block
                 DX = Selector for allocated block

                 If function was not successful:
                 Carry flag is set.
                 AX = DOS error code:
                      07h  memory control blocks damaged
                      08h  insufficient memory  available to allocate as
                      requested
                 BX = Size of largest available block in paragraphs

            Programmer's Notes

                 o    If the size of the block requested is greater than
                      64K bytes (BX > 1000h) then contiguous descriptors
                      will be  allocated.  To access the next descriptor
                      for the  memory block  add  the  value  return  by
                      function 0003h  (see  Function 0008H)  to the base
                      selector.
                      If more than one descriptor is allocated under 32-
                      bit DPMI  implementations, the  limit of the first
                      descriptor will  be set  to the size of the entire
                      block.   All subsequent  descriptors will  have  a
                      limit of 64K except for the final descriptor which
                      will have  a limit  of Block size MOD 64K.  16-bit
                      DPMI implementations  will always set the limit of
                      the first  descriptor to  64K even when running on
                      an 80386.
                 o    Your program should never modify or deallocate any
                      descriptors allocated  by this function.  The Free
                      DOS Memory  Block  function  will  deallocate  the
                      descriptors automatically