Why 8-bit?

“8-bit” is the size of the numbers the processor handled: 0–255. Sound and image were made by small dedicated chips with very few options — and every limit became a style.

Bits, bytes and hex

A bit is 0 or 1. Eight bits make a byte: 256 combinations, 0 to 255 — the “8” in 8-bit. Click the bits:

Programmers wrote bytes in hexadecimal (base 16): each group of 4 bits becomes one symbol, 0–9 then a–f (10–15). So a byte is always 2 symbols: ff = 255, 80 = 128. Many chip settings fitted in 4 bits — a single hex digit: 16 volume levels, the C64’s 16 colours, 16 noise speeds. Chipgrid uses base 36, which starts like hex and goes on to z = 35 (see the Manual).

A short history

1977	Atari 2600 — its TIA chip has 2 voices and a famously out-of-tune scale.
1982	ZX Spectrum — a 1-bit “beeper”: the processor clicks the speaker on and off itself
1982	Commodore 64 — the SID chip (Bob Yannes): 3 voices, 4 waveforms and a real analogue filter.
1983	Famicom (NES in 1985) — the 2A03: 2 pulses, triangle, noise and a sample channel. This tool emulates it.
1985–86	Koji Kondo’s Super Mario Bros. and Zelda, Hirokazu Tanaka’s Metroid; on the C64, Rob Hubbard and Martin Galway.
1987	Soundtracker on the Amiga: music written as rows of notes — the “tracker”. The demoscene grows around these machines.
1989	Game Boy — 2 pulses, a tiny wavetable, noise. 160×144 pixels, 4 shades of green.
1998–2000	Nanoloop and LSDJ turn the Game Boy into an instrument: chiptune leaves the games.
2006–12	Blip Festival, New York: chiptune on stage. Later Anamanaguchi, Chipzel…
2015	PICO-8: a “fantasy console” with 8-bit limits on purpose.

The techniques, by ear

arp	An arpeggio: a chord with one voice, one note per frame.
duty	Timbre by pulse width (duty): 12.5%, 25%, 50%.
kick	A tone with a fast pitch drop becomes a drum.
noise	Noise: hats, snare, metal — the shift register at different speeds.
echo	No reverb chip? A fake echo: the melody again, quieter, 3 ticks late, on the second voice.
laser	Pitch slides: the sound effects of every shoot-’em-up.
steal	Channel juggling: the kick interrupts the bass on the same voice.

1 · Four voices, no more

The NES chip had 2 pulse channels, 1 triangle and 1 noise. Melody, harmony, bass and drums: four roles, four voices. Here P and G share the two pulses, B owns the triangle, N owns the noise. A fifth note steals a channel — watch the meters flash STEAL.

2 · The pulse and its duty

Same pitch, three widths: 12.5%, 25%, 50%. The narrower the pulse, the more high harmonics: thin and nasal. 50% is the square: only odd harmonics, hollow.

3 · The triangle, in 16 steps

A 4-bit counter going 15→0→15: a staircase. It can’t change volume — just on or off.

4 · Noise from a shift register

15 bits in a row. Each clock: XOR two bits, shift everything right, put the result on the left. The last bit is the output. Mode 0 repeats after 32,767 steps (hiss); mode 1 after 93 (a metallic tone). The clock speed is the “pitch”.

5 · Volume in 16 steps

4 bits of volume = 16 levels. A fade-out is a staircase you can almost hear step by step.

6 · Arpeggios

No voice left for a chord? Play its notes one after another, once per video frame (50/s in Europe). The ear fuses them into a shimmering chord.

7 · The picture

Low resolution (NES: 256×240; this screen: 160×120), a tiny palette, 8×8 sprites. Tricks: mirroring sprites to halve memory, dithering (a fixed checker pattern) to fake colours that don’t exist, palette cycling (change the colours, not the pixels), raster bars, hardware scrolling and parallax (layers at different speeds) to fake depth. All of these can be coded in the grid too: see the Visuals examples.

Going further

FamiTracker / Dn-FamiTracker (NES), LSDJ (Game Boy), GoatTracker (C64), Furnace (all chips), Orca (the grid language this tool borrows from), PICO-8.