INT E0 - REAL/32 - "DEV_TWAITFLAG" - TIMED WAIT ON SYSTEM FLAG
	CL = B7h
	DS:DX -> Flag Parameter Block (FPB) (see #04058)
Return: AX = status
	may destroy SI,DI,DS
Note:	if the flag was already set, this function returns immediately
SeeAlso: INT E0/CL=84h,INT E0/CL=85h


Format of REAL/32 Flag Parameter Block (FPB):
Offset	Size	Description	(Table 04058)
 00h	WORD	number of system flag on which to wait
 02h	WORD	maximum number of system ticks (see INT E0/CL=9Ah) to wait