The Tektronix M001 (P/N 155-0009-00) is a horizontal lockout logic monolithic integrated circuit in a 16-pin DIP, designed by Les Larson.
It receives inputs from the horizontal chop and alt. binary, "A" sweep delay control, "A" sweep gate, "B" sweep holdoff and "B" sweep gate. Logic is performed on these signals to provide lockout for "A" sweep or "B" sweep and alternating signals for the horizontal chop and alt. binary.