155-0011-00
The Tektronix M012 (P/N 155-0011-00) is a clock and chop blanking monolithic integrated circuit in a 16-pin DIP, designed by Les Larson.
It generates the 2 MHz chop clock signal for triggering the chop counter (155-0010-00 aka M004) as well as the chop blanking waveform. The blanking waveform can be delayed in time and varied in width over a certain range to accommodate different delay lines. It also has fine logical inputs which are the plug-in and mainframe modes that are used to decide if chop blanking should be used at a certain time.