I second this recommendation, especially Chamberlin's discussion of filters. He provides an implementation of a state-variable filter (low-pass, high-pass, band

I second this recommendation, especially Chamberlin's discussion of filters. He provides an implementation of a state-variable filter (low-pass, high-pass, band-pass, and notch) in, if I recall correctly, four lines of BASIC. I wrote a version of it in ARM Thumb assembler for the Cortex-M0 and it sounded quite good. [1] Despite being published over 30 years ago, it's a great resource for anyone interested in sound synthesis on resource-constrained systems. [1] - https://github.com/74hc595/LPC1114-Synthesizer/blob/master/kernel.S https://github.com/74hc595/LPC1114-Synthesizer/blob/master/k...