# 1960's video showing early computer design & simulation of a low-pass filter circuit?

I ran across this IBM computer aided design and simulation software demonstration from the 1960's in the video The Incredible Machine (1968)

The gain vs frequency plot shows what looks like the characteristics of a low-pass filter, but is that what's shown in the diagram? Could the 3-terminal device at the bottom be a transistor?

The GIF was made at about 02:44 in the video.

• At one point their simulation doesn't work/ flags an error and one says to the other we forgot to put in the input impedance of the amplifier. So it might be an amplifier equivalent circuit. The three terminal symbol I have no idea, looks vaguely like a variable resistor – IC_Eng Apr 16 at 14:52