INT 31 - DPMI 0.9+ - ALLOCATE DOS MEMORY BLOCK

	AX = 0100h
	BX = number of paragraphs to allocate
Return: CF clear if successful
	    AX = real mode segment of allocated block
	    DX = first selector for allocated block
	CF set on error
	    AX = DOS error code (07h,08h) (see #01680 at INT 21/AH=59h/BX=0000h)
		(DPMI 1.0+) DPMI error code (8011h) (see #03143)
	    BX = size (in paragraphs) of largest available block
Notes:	multiple contiguous selectors are allocated for blocks of more than 64K
	  if the caller is a 16-bit program
	never modify or deallocate returned descriptors
	not supported by MS Windows 3.0 in Standard mode
SeeAlso: AX=0101h,AX=0501h