INT 21 - DOS 2+ - ALLOCATE MEMORY                                               
	AH = 48h
	BX = number of paragraphs to allocate
Return: CF clear if successful
	    AX = segment of allocated block
	CF set on error
	    AX = error code (07h,08h) (see #01680 at AH=59h/BX=0000h)
	    BX = size of largest available block
Notes:	DOS 2.1-6.0 coalesces free blocks while scanning for a block to
	.COM programs are initially allocated the largest available memory
	  block, and should free some memory with AH=49h before attempting any
	under the FlashTek X-32 DOS extender, EBX contains a protected-mode
	  near pointer to the allocated block on a successful return
SeeAlso: AH=49h,AH=4Ah,AH=58h,AH=83h