155-0012-00
The Tektronix M015 (P/N 155-0012-00) is a Z Axis Logic monolithic integrated circuit in a 16-pin DIP, designed by Les Larson.
Under control of the horizontal switch drive, it selects the beam intensity - A or A intensified by B.
Additional functions are chop blanking for vertical and horizontal, external and plug-in Z axis input, and fast limiting of the composite signal. The signals are further limited at slow sweep speeds to prevent burning of the CRT.