INT 16 U - PCIBM PC Tools v8+ CPTASK, VSAFE - ???
	AX = FF9Dh
	ES:BX -> ??? word
Return: ???
Note:	if ES is non-zero, the word pointed at by ES:BX determines whether the
	  ??? flag is cleared (word = 0000h) or set (word is nonzero).	The
	  flag is always cleared if ES=0000h.