Sound can be created from a speaker of course, and for computers in the early 80's, good old 8-bit programmable sound generation could be produced using sound chips. The sound chip simply generated a wave form and you could control its frequency and sometimes volume or the amplitude (height) of those waves. You could also control the duration of the tones and with great dedication you could program music. This 8-bit style music has some dedicated musicians making amazing productions that are quite complex. This one below, I highly recommend for your listening pleasure. If you ever liked Metallica, you will like this. I recall seeing the video of Enter Sandman during its premiere on MuchMusic in the 90's (Canada's version of MTV). Enjoy.
listen on YouTube Enter Sandman in 8-bit style by The Greatest Bits: http://t.co/UgTpjjw5if
— Kenneth Mitton, PhD (@kpmitton) February 28, 2015