I’ve just read ‘Microsound’ by Curtis Roads. I was well aware of the microsound movement, but hadn’t realized the depth of the theory behind granular synthesis, with it’s history going back to the 1940s, and early practise from Xenakis (using tapes) and this lad, Curtis Roads, programming his own granular synth on a PDP-11/20 in 1974 - what a bad-ass! Check this site for some good background and papers.
I found these videos of Curtis Roads, via the site linked above.