Abstract: A signal display system having a visual display and a display signal generator in which a semiconductor junction target has a high conductivity P layer, a low conductivity N layer, and a surface layer of insulating material having holes in the shape of letters or other characters. The target semiconductor junction is reverse biased so that when an electron beam striking the target is scanned over the character apertures, it will produce carrier multiplication in the target and an output signal several orders of magnitude greater than a conventional monoscope. The same principle may be used for a camera pickup tube when beam electrons returning from a light sensitive target are multiplied on striking a reverse biased junction target.