This is my adaptation of the great little software synthesizer pico_synth_ex by Ryo Ishigaki (ISGK Instruments) (https://github.com/risgk/pico_synth_ex) to serve as a new engine for a cheap toy musical keyboard. The new engine boasts two oscillators, featuring descending sawtooth and square waveforms, a customizable filter with resonance control, cutoff modulation, a Decay-Sustain amp envelope, and an LFO for added modulation possibilities.