Going on the assumption that the SR Apex crankset and what appears to SunTour Vx deralleurs are OEM, it should one of the 800 series models, Timeline could be anywhere from about 1980 to 1985. The seat post diameter should tell us if it's an 800 Dilettante or the 850 Paris-Roubaix. Date codes on the back of the derailleurs and crankarms should allow us to narrow down the date.