From Beeps to Chips
The first sounds in computer games were very simple. Some machines had only a small speaker that could be switched on and off, producing a click or a tone. A programmer made a note by switching the speaker at a steady rate, and the pitch depended on how fast it was switched. This used the main processor for timing, so a program could not easily play music while doing much else.
Arcade machines and later home systems added dedicated circuits for sound. These sound chips took over the job of generating tones, leaving the processor free to run the game. Their design determined what a composer could do, and so they had a strong influence on how game music sounded.
What a Sound Chip Does
Most early sound chips worked on a few basic building blocks.
- Channels (sometimes called voices). Each channel plays one sound at a time. A chip with three channels could play, say, a melody, a harmony and a bass line together, but nothing more.
- Waveforms. A channel produces a repeating wave whose shape affects its tone. Simple shapes, such as square or triangle waves, sound buzzy or hollow compared with a real instrument.
- Noise. A channel can produce random-sounding hiss, useful for percussion, explosions and wind.
- Volume control. A chip may allow the loudness of a channel to change over time, which helps shape a note so it starts sharply and fades.
Chips differed in how many of these features they offered and how flexible they were. Some home computers of the early 1980s included chips that could produce a variety of waveforms and filter the sound, which gave their music a recognizable character. Others, popular in home machines and arcade boards, had three tone channels and a noise channel. Console designs from the mid-1980s typically offered a small number of tone channels, a noise channel and sometimes a channel for short recorded samples. The exact specifications varied between models, so it is safer to describe the general pattern than to rely on any single chip.
Composing Within Limits
Because channels were few, composers had to work with the equivalent of a very small band. They developed techniques that are still recognizable:
- Arpeggios. To suggest a chord on a single channel, the program rapidly cycled through the notes of the chord. The ear tends to blend them, and the result sounds fuller than a single note.
- Sharing channels. A sound effect, such as a jump or a coin pickup, might temporarily borrow a channel from the music. This is why background music in some games drops out for a moment when something happens.
- Short loops. Memory was limited, so tunes were often brief and repeated indefinitely. A composer had to write something that did not become annoying after hours of play, which is harder than it sounds.
- Envelopes and vibrato. Programmers adjusted volume and pitch over the length of each note to imitate the behavior of real instruments.
The music was often entered as numbers or in special editing programs, and some developers wrote their own tools. In small companies, a programmer might compose the music as well, though specialist composers became more common as the industry grew.
Frequency Modulation and Sampling
Later sound hardware expanded the range. One approach, called FM synthesis, used one wave to alter another, producing richer and more bell-like or metallic tones from a small number of components. Chips of this kind appeared in some arcade boards, home computers and consoles in the late 1980s and early 1990s, and they gave those systems a distinct sound.
Another approach was sampling, where short recordings of real sounds were stored in memory and played back at different pitches. Sampling could produce drums, voices and instruments that were impossible with simple wave generators, but samples took up memory, so they were used sparingly on early systems. As storage grew, particularly with optical discs, games could include long recorded tracks, and the gap between game music and other music narrowed. This is also related to the older tradition of computer music, in which researchers had experimented with synthesizing sound on large machines.
A Lasting Style
Many players associate certain sounds strongly with games they played as children. The buzzy tones and rapid arpeggios of the period created a style known as chiptune, which musicians continue to make, sometimes on original hardware and sometimes with software that imitates it. For some, the limitations are part of the appeal, in the same way pixel art draws on the visual limits of early displays.
It would be wrong to call the music simple because it was limited. Many composers made tunes that remain familiar decades later, using only a few notes at a time. Historians note that the sound of a game is often a better guide to the hardware inside than a spec sheet would be, because each chip left a kind of fingerprint.
The Present
Modern games generally use recorded or orchestral music and often respond to what the player is doing, shifting layers of sound as a scene changes. That approach has roots in the earlier practice of switching between short loops, even though the technology is far more capable. Understanding the old chips helps explain why game music developed its own conventions and why it is treated today as a form of composition in its own right.