Once upon a time, all music was made mechanically...something had to be hit with a hand or a stick...or strummed or plucked...or air had to be forced over a reed or through a valve...
Then along came electricity...it took a while, but electricity was tamed so that it could not only power new forms of musical instruments, but the energy itself could be made musical...
By the beginning of the 1980s, the people of planet earth were most pleased at what they had accomplished...but in the background, some people knew that there was still more work to be done....
They began asking “what if anything could be made into music?”...others still mused “what if we could take existing music, chop it up and reassemble it into something brand new?”...
Some used the old ways, chopping up these sounds mechanically using proven machinery like turntables and tape machines...but others learned to use new inventions called “computers” and “samplers”...
And so it came to pass that all through the 80s, people began to experiment with electricity and the new machines...and by the time the decade ended, there was plenty of new and interesting music to go around...music was being made by machines, orchestrated by computers and programmed by punks...and things would never be the same again. 
This is the complete history of alt-rock, chapter 10...