A chiptune, or chip music, is music written in sound formats where all the sounds are synthesized in realtime by a computer or video game console sound chip, instead of using sample-based synthesis. The "golden age" of chiptunes was the mid 1980s to early 1990s, when such sound chips were the most common method for creating music on computers. Chiptunes are closely related to video game music, which often featured chiptunes out of necessity. The term has also been recently applied to more recent compositions that attempt to recreate the chiptune sound for purely aesthetic reasons, albeit with more complex technology.
Early computer sound chips had only simple tone and noise generators with few channels, imposing limitations on both the complexity of the sounds they could produce and the number of notes that could be played at once. In their desire to create a more complex arrangement than what the medium apparently allowed, composers developed creative approaches when developing their own electronic sounds and scores, employing a diversity of both methods of sound synthesis, such as pulse width modulation and wavetable synthesis, and compositional techniques, such as a liberal use of arpeggiation. The resultant chiptunes sometimes seem harsh or squeaky to the unaccustomed listener.
For the MSX several sound upgrades, such as the Konami SCC, the Yamaha YM2413 (MSX-MUSIC) and Yamaha Y8950 (MSX-AUDIO, predecessor of the OPL3) and the OPL4-based Moonsound were released as well, each having its own characteristic chiptune sound.
Most of (but not all) chip sounds are synthesised by simply dividing a clock square wave to get a square wave of desired frequency, and sometimes using a sawtooth/triangle wave from volume LFO or an (ADSR) envelope to get some kind of ring modulation. LFOs are used to control or influence a sound parameter such as pitch or filters in a repeating cycle. It can be found as function of the SID chip.
The technique of chiptunes with samples synthesized at runtime continued to be popular even on machines with full sample playback capability; because the description of an instrument takes much less space than a raw sample, these formats created very small files, and because the parameters of synthesis could be varied over the course of a composition, they could contain deeper musical expression than a purely sample-based format. Also, even with purely sample-based formats, such as the MOD format, chip sounds created by looping very small samples still could take up much less space.
As newer computers stopped using dedicated synthesis chips and began to primarily use sample-based synthesis, more realistic timbres could be recreated, but often at the expense of file size (as with MODs) and potentially without the personality imbued by the limitations of the older sound chips.
The standard MIDI file format, together with the General MIDI instrument set, describes only what notes are played on what instruments. General MIDI is not considered chiptune as a MIDI file contains no information describing the synthesis of the instruments.
For the above reasons the classic chiptune 8-bit sound can be recognised from its synthesised square or pulse wave instruments, simple white noise percussion and heavy use of ultra-fast arpeggios to emulate chords of three or four notes on a single channel (due to hardware limitations, several notes must be placed on the same channel).
Demoscene intros came to feature their own particular style of chiptune music. Although chiptune could historically refer to any style of music, the term is mostly used today to refer to the style of music used in these intros, since other styles of music have moved on to more sophisticated technology.
More recent "old school" or "demostyle" MOD music, although sample-based, continues the style of the chiptunes used in these intros; new compositions in this style can still be regularly found at www.chiptune.com or www.chip-on.com (new chiptunes from old computers/formats can be found here as well).
The chip scene is far from dead with "compos" being held, groups releasing music disks and with the cracktro/demo scene. New tracker tools are making chip sounds available to less techy musicians. For example, Little Sound DJ for the Nintendo Game Boy has an interface designed for use in a live environment and features MIDI synchronization. The NES platform has the Midines, a cartridge that turns the system into a full blown hardware MIDI controlled Synthesizer. On the DOS platform, Fast Tracker is one of the most famous chiptune makers because of the ability to create hand-drawn samples with the mouse.
Contemporary interest in chipping has also led to numerous web sites dedicated to the history of music groups, artists, and antique platforms.
In the last couple of years, chip music has returned to modern gaming, either in full chip music style or using chip samples in the music. Games that do this in their soundtrack include Mega Man Battle Network, Seiklus, and Tetris DS.
Chiptune music is relatively unknown in North America, and most of the chiptune artists are European, Australian or Japanese. Due to Myspace, chiptune artists have gained some notoriety. There has however been a small amount of artists coming out of the United States, Canada, and Mexico.
A notable chiptune artist today is 8 Bit Weapon, who has completed chiptune music projects for Disney, Cartoon Network (Europe), Microsoft, Nokia, Kraftwerk, Information Society, Erasure and has even appeard live on national television via G4TV's Attack of the Show.