Chip-o-matic and Chiptunes

What is Chip-o-Matic?

Chip-o-Matic is accompaniment software made especially for Maker Faire 2012. The goal was to create an exhibit which not only taught people how chiptunes worked, but allowed even people unfamiliar with the style to instantly create rich compositions. It is written in Pure Data by Louis Gorenfeld and will run on a variety of computers and operating systems. Here you see it running on Linux.

The Rundown (Controls)

The lower octaves choose the bassline's note.
Use the middle octaves to trigger chords. You only need to play the first note of the chord.
Play a synth lead using the higher octaves. Hold a note for vibrato.
Click the grid of horizontal buttons in the left pane to select a beat.
Draw on the lead waveform to alter its tone
Chords slide between three notes rapidly to produce an arpeggio, and are in D Phrygian mode

Conserving Voices and Other Cleverness

Early computers could not play more than a few sounds at a time and were typically limited to 3 or 4 voices of simultaneous audio. A voice can be one note, a drum hit, or a sound effect. Many 'chiptunes' work around this limitation using clever tricks.

For example, in this demonstration, the entire composition you play is only 3 voices, although it sounds like more. This is because multiple instruments can share one channel in many computer systems. In this particular case, the drums and bass both share the first channel. The trading off between the drums and bass is so quick that your ears perceive it as multiple simultaneous sounds, although you are really only hearing one at a time. This leaves two more channels for the chords and the lead synth. If you watch the oscilloscopes on the main screen, you can see this illustrated.

The chords fit into only one channel in much the same way that the bass and drums are able to coexist. Instead of playing three notes simultaneously, as you might expect playing a triad chord on a piano, it instead alternates rapidly between three pitches.

Finally, the snare drum sound is done using another variation on this trick. Most good synthesized snare drums use up to three voices, and both random noise (a static-like burst) and tone are at least required to produce a thick sound that is reasonably snare-like. Instead of using two voices for noise and tone, we again flip between noise and tone rapidly.

It's worth noting that not all of these techniques translate to all chips. For example, the NES couldn't do the above-mentioned snare or bass tricks because each voice was dedicated to a particular tone. That is, you couldn't make one voice play both noise and tone, even if they weren't sounding simultaneously.

80s Computer Synth Technology

Chip-o-Matic also demonstrates several different old synthesis techniques: The chords are done using a beep-like tone called a pulsewave, akin to what you might hear out of a NES or Nintendo GameBoy. The bass is similar, but is run through a filter which removes the highs, giving it a deeper, rounder sound. This is like the capabilities of a Commodore 64 (1982). Finally, the lead uses a sample-based technique which manipulates the sound as it plays. This trick saw use in some songs off the Commodore Amiga computer (1985).

Another popular synthesis technology in the 80s was FM Synthesis. It's not represented here by Chip-o-Matic, but deserves a mention nonetheless. It was used in systems such as the Sega Genesis, many PC sound cards, and countless arcade games. Though it's often described as tinny, it is actually very versitile and can represent many natural instruments-- especially chimes and instruments with sharp attacks.

Chiptuning: Where It's From, Where It's Going

"Chiptune" is a term which has meant different things at different times. Though most people today would say that a chiptune is music played off of a computer chip, this wasn't always the definition. For example, throughout the 90s, people (primarily in parts of Europe) wrote chiptunes by writing songs which didn't take a lot of data for their instrument sounds. These small instrument sound samples-- typically just a few bytes in length-- resembled the sound of earlier chip music on systems such as the Commodore 64 or other older computers. This was as opposed to the richer sounding, full-quality music made for the computers of the day.

These days, chip music is made in a wide variety of ways. Some musicians use emulators (software which imitates specific hardware), some use game machines running music programs designed for this very purpose. Others still use the sample-based techniques mentioned in the previous paragraph. And, in the last few years, groups such as Anamanaguchi have gained in popularity, fusing more traditional rock music with the chiptune sound.

Thanks for checking out our booth at Maker Faire! Be sure to check for upcoming chiptune concerts in the Bay Area at http://www.8bitsf.com!

--Louis Gorenfeld