INT 21 P - Phar Lap 386/DOS-Extender - MAP PHYSICAL MEMORY ATIBM PC AT END OF SEGMENT
	AX = 250Ah
	ES = segment selector in the Local Descriptor Table (LDT) of segment
	     to modify
	EBX = physical base address of memory to map (multiple of 4K)
	ECX = number of physical 4K pages to map
Return: CF clear if successful
	    EAX = 32-bit offset in segment of mapped memory
	CF set on error
	    EAX = error code
		08h insufficient memory to create page tables
		09h invalid segment selector
SeeAlso: INT 31/AX=0800h