Re-make sound synthesizer

[sam-astro]

The current implementation of the sound synthesizer has audio artifacts and pitch inaccuracies, mainly because each channel is loaded from an audio file and its speed changed, instead of being generated dynamically.

The system needs to be remade to create 4 channels of audio (1 and 2 are square waves, 3 is a triangle wave, and 4 is noise).

Unfortunately, I don't have much experience with creating an audio synthesizer, so any help would be appreciated.
An application you can use to test the sound is the music tracker at https://github.com/sam-astro/MusicalYabal/blob/main/musical.asm
(press underscore/minus key to play/pause)