Exhibit / play it
Chip Synth
Game music was always written for a particular machine, and the machine decided what it could sound like. Play the same few notes through five generations of game sound and hear the limits change.
How to use the synth
Sound starts off. Press Turn sound on when you are ready; the volume starts low and every note goes through a limiter, so nothing can suddenly get loud. Pick a generation, then play the keys with a mouse or finger, or with your computer keyboard: the home row from A to K plays the white keys, and W, E, T, Y and U play the black ones. You can also tab to a key and press Enter or Space.
The grid below is an eight-step sequencer. Each column is a step, each row a note, and the bottom row is the noise drum. Switch cells on, press Play, and change generation while it loops. With a keyboard, the arrow keys move between cells. Nothing is recorded and nothing leaves your browser.
Sound
Sound is off. Nothing plays until you turn it on.
Generation
Keyboard
Sequencer
A sound is a shape
A speaker makes sound by moving back and forth. How often it moves each second is the pitch: the A above middle C moves 440 times a second, and every octave up doubles that. The shape of the movement is the tone. A smooth sine wave sounds pure and soft. A square wave, which jumps between two positions, sounds buzzy and hollow, because a sharp corner is made of many higher tones stacked together.
Every generation of game hardware made its sound a different way, and you can hear each method in the music people wrote for it.
Five generations
Square-wave chips. The earliest home computers and many arcade boards used a small chip with three square-wave voices like the ones here. Each voice was a counter that flipped a wire on and off. The chip could not play any pitch you liked: it divided its own clock by a whole number, so most notes came out a little sharp or flat. Volume came in sixteen fixed steps, and a fourth voice made noise for drums. If you want a chord with only three voices, you flick one voice between notes very fast, which is where the bubbling arpeggios of early game music come from.
The 8-bit console. A typical 8-bit console had two pulse voices, a stepped triangle for bass and a noise voice. A pulse wave is a square wave whose “on” part can be made thinner. Thin pulses sound reedy and nasal; the full square sounds round. The triangle was built from sixteen coarse steps, which gives the bass a faint buzz. Four voices, and no more: composers became expert at making that feel like a band.
Four-operator FM. In the 16-bit years, many machines used frequency modulation. One sine wave, the modulator, bends the pitch of another, the carrier, so quickly that you hear a new, richer tone instead of a wobble. Make the modulator fade faster than the carrier and each note starts bright and mellows, like a struck bell or a plucked bass. Four such operators per voice made brass, bells and slap bass from almost no memory.
The sample era. Some computers of the late 1980s, and the sound cards of the 1990s, could play back short recordings, called samples, faster or slower to change the pitch. Memory was scarce, so samples were tiny, stored at low rates and in 8 bits. That gives a gritty, slightly crunchy tone. Our sample is not a recording of anything: we synthesise a plucked string, then crush it the same way.
The modern soft synth. Today the chip is software, with as many voices, waves and effects as you like. The skill is choosing restraint. Our patch is two slightly detuned saw waves through a soft filter, the kind of calm pad you hear in many games now.
Why some chip notes are slightly out of tune
An old sound chip made a note by counting ticks of its own clock and flipping the output every so many ticks. To play a note, the program gave the chip a whole number, the period. Because the period must be a whole number, only some pitches are possible. High notes suffer most, because there the gap between one whole number and the next is a big jump in pitch. When you play a key in the two chip generations, the line under the keyboard shows the exact pitch and the pitch the chip actually plays.
We use made-up clock speeds in the same range as real machines, so the errors are real errors of this kind, but not a copy of any one chip.
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Play the history
Cabinets where the sound is part of the game: rhythm, beat and timing.