x0x is a unique MIDI sequencer that was designed from the ground up to be a live performance tool. It combines a Tracker-like sequence editor, a 606/808/909 style drum machine interface, and a 202/303 style piano key note input. The sequencer is unique in that editing is real-time, with no interruption in the sequencer output. This flexibility makes it a performance instrument in ways that inflexible sequencers of the past could not be.
x0x is fitted with a DSP-based synthesizer engine which can be programmed and controlled from the x0x user interface, allowing the box to make its own sounds as well as controlling other MIDI gear. It runs a one-of-a-kind monophonic dual oscillator synthesizer engine called the Death Synth.
The x0x features MIDI in/out/thru, MIDI clock synchronization and generation, eight MIDI continuous controller knobs, and a large 240×64 graphics LCD.
This project is the first hardware design that I did directly after college, and as such, it is not terribly sophisticated in implementation. It is based around an off-the-shelf 68HC11 microcontroller board, an off-the-shelf Analog Devices ADSP 2181 evaluation board, and a large custom PC board which contains all of the user interface elements such as buttons, knobs, switches, display, MIDI interface, etc. Firmware is written in C for the sequencer, and assembly for the DSP.
x0x was a collaborative effort with Noah Vawter, now of DIY DSP fame. I designed the hardware and did the initial firmware driver implementation. Noah wrote most of the sequencer firmware as well as the DSP synthesis engine.