An Atari Punk Console is an electonic musical instrument that produces "low-fi" sounds that resemble classic Atari console games from the 1980s, with a square wave output similar to the Atari 2600.

Who invented it?
There are 3 people who contributed to the final instrument which is called an Atari Punk Console. Hans R. Camenzind invented the 555 timer IC, Forrest M. Mims III designed the Stepped Tone Generator and Kaustic Machines called the circuit the Atari Punk Console beucase of the "low-fi" sounds that resemble classic Atari console games from the 1980s it makes

The Atari Punk Console (commonly shortened to APC) is a popular circuit that utilizes two 555 timer ICs or a single 556 dual timer IC. The original circuit, called a "Stepped Tone Generator", was published in a Radio Shack booklet: "Engineer's Notebook: Integrated Circuit Applications" in 1980 and then in "Engineer's Mini-Notebook - 555 Circuits" by its designer, Forrest M. Mims III (Siliconcepts, 1984). It was named "Atari Punk Console" (APC) by Kaustic Machines crew because its "low-fi" sounds resemble classic Atari console games from the 1980s, with a square wave output similar to the Atari 2600. Kaustic Machines added a -4db line level output to the circuit which was originally designed to drive a small 8 ohm speaker.

This is the schematic with a 556