I picked up a broken ML-303 pretty cheap in Berlin, which was kind of a "Frankenstein" machine, because it was using the Analog Board from AcidCode's ML-303V3 and some board between V3 and V5 from AcidCode, which was never released. Unfortunately the Firmware was buggy and the Oscillator on the analog board was unstable and sounding awful, so I decided: Lets make a new brain for it.
So I grabbed my PJRC Teensy 3.0 ARM Board, Saleae Logic Analyzer and started reverse engineering the connections of the synthesizers.
As soon as I found out the original had the Data Lines D0-D5, Slide (which also acts as latch), Gate and Accent I started writing my own firmware.
First, the firmware was only replacing a basic MIDI-Controllable ML-303.
Then I started to remove the middle cable of the Waveform Switch, which goes
directly to the VCA and then to the VCF of the ML-303, so I could inject a Waveform.