What do Electronic Waveforms Sound Like 

I believe 8 bit would have used square waves, as it’s a digital chip so it would have been much easier and very natural to use a square wave, as it’s just pulsing a voltage on and off

All of the waveforms in the video were rather basic ones, so they would have been easy to generate on early equipment although they sounded rather "electronic."

The reason the 8-bit video game sounds like a square wave is because original games didn't have a way to vary the position of the speaker in steps. The speaker was "toggled," all the way up or all the way down, which corresponds pretty strongly with a square wave. There are two ways to get variable levels on a speaker: a Digital-to-Analog Converter (DAC) and Pulse Width Modulation (PWM). A DAC is a special chip where you feed it a number and it pushes the speaker to a level corresponding to that; if you have an 8-bit DAC, the numbers / "sample" values are 0 - 255. 0 will have the speaker all the way up (at rest). 255 will have the speaker all the way down (magnet pulling on the diaphragm, all the way). 128 will have it about halfway. Instead of just feeding it max / min values, you can feed it intermediate values, such that it approximates the multiple steps of a sine wave. If your "sample rate" is high enough, you can replicate any of these wave forms, with a pretty high degree of accuracy. CDs and most modern sound cards / modules use a DAC, typically using 16-bit values and 44,100 samples per second (x 2 channels for stereo). PWM entails changing between up / down much faster than the speaker can move. By changing the value hundreds of thousands of times / second, the speaker will start moving one direction, then move the other direction, and then head the first direction, before it can go full up / down. This allows you to achieve multiple levels on the speaker, resulting in the ability to generate more-complex waves. Direct Stream Digital, commonly used on Super Audio CD, does something similar to this, with the value cycling between 0 and 1 nearly 3 million times / second. Modern chips, like Arduinos and such, have both DAC and PWM circuits in them, such that you can use either one. You typically use the DAC for things like playing music and use PWM for things like illuminating an LED partway, etc. I can recall playing with an Apple II, back in the day. You'd poke (or peek) a particular memory location and it would toggle the speaker (from up to down, or vice versa) for each access. If you toggled it 528 times per second, it would oscillate the speaker at 264 Hz, which is middle C. It had only one volume level and it could really only play one note at a time. There was a demo program which actually played 2-note chords but it was written in machine language and could only play one song (part of the "Blue Danube Waltz," IIRC). It had to, essentially, calculate the times between the peaks for each pair of notes and toggle the speaker at the appropriate moments to accomplish that. Running in machine language, it could toggle the speaker up to about 20k times per second, which could produce two-note chords, but wasn't really fast enough for 3-note chords. It still sounded "electronic," meaning it was really doing a couple square waves, not moving fast enough to do PWM and get something smoother.

Thanks.