Kick 808 1
You can find a much better version of the 808 BD here.
The patch tries to recreate the kind of 808 kick drum that gets made on fixed architecture monosynths, except it uses the sine wave from VCO-A instead of a self-oscillating filter.
To recreate the pitch bend you get from the envelope controlling the filter frequency, ENV-B modulates VCO-A FM.
ENV-B simulates the batter head of a kick drum, providing the initial punch and attack of the sound.
ENV-A uses a longer envelope to control the VCA. This envelope simulates the resonant head of a kick drum, contributing to the decay and body of the sound.