The semicircle is not an op amp. Although it can also be constructed with an op amp, it is a logic AND gate. What you call an op amp with a hole in the front is actually a logic NOT gate. In fact, this circuit In , there is a digital part, which is a circuit composed of logic gates, which are relatively small triangles, half-moons, and semicircles. For logic gates, a hole represents the reverse direction, and it can also be considered to play the role of a NOT gate. Since your diagram is incomplete, I can't tell you the specific function of your circuit. This circuit presumably controls signal processing. It is recommended that you first understand some representation methods of logic gates, then you will understand this picture better. The one with a square chip should be a Schmitt trigger, used for shaping, while the one without a square chip is a normal comparator.