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20 lines
962 B
Markdown
20 lines
962 B
Markdown
# ZX Spectrum beeper
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rather than having a dedicated sound synthesizer, early ZX Spectrum models had one piezo beeper, controlled by Z80 CPU and ULA chip. its capabilities should be on par with an IBM PC speaker... right?
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not really - very soon talented programmers found out ways to output much more than one square wave channel. a lot of ZX beeper routines do exist, but Furnace only supports two engines:
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- a Follin/SFX-like engine with 6 channels of narrow pulse wave and click drums.
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- QuadTone: PWM-driven engine with 4ch of pulse wave with freely variable duty cycles and 1-bit PCM drums.
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## effects
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- **`12xx`**: set pulse width.
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- **`17xx`**: trigger overlay drum.
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- `xx` is the sample number.
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- overlay drums are 1-bit and always play at 55930Hz (NTSC) or 55420Hz (PAL).
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- the maximum length is 2048!
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## info
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this chip uses the [Beeper](../4-instrument/beeper.md) or [Pokémon Mini/QuadTone](../4-instrument/pokemini.md) instrument editor.
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