29 lines
1.3 KiB
Markdown
29 lines
1.3 KiB
Markdown
# Atari Lynx instrument editor
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Atari Lynx instrument editor consists of these macros:
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- **Volume**: volume sequence
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- **Arpeggio**: pitch in half-steps
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- **Duty/Int**: bit pattern for LFSR taps and integration
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- **Panning (left)**: output level for left channel
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- **Panning (right)**: output level for right channel
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- **Pitch**: fine pitch
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- **Phase Reset**: trigger restart of waveform
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## Audio generation description
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Atari Lynx generates sound using a 12-bit linear feedback shift register with configurable tap. Nine separate bits can be enabled to be the source of feedback: 0, 1, 2, 3, 4, 5, 7, 10 and 11. To generate _any_ sound at least one bit _must_ be enabled.
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### Square wave
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The LFSR is shifted at the rate define by sound pitch and generates square wave by setting channel output value to +volume or -volume, depending on the bit shifted in.
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### Triangle wave
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Alternatively when "int" bit is set sound wave is generated by adding or subtracting volume from output effectively producing triangle wave.
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#### How triangle wave works?
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Hint: To obtain triangle set bits "int" and "11" in "Duty/Int" sequence and set volume to about 22.
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By enabling 11th tap bit the value shifted in is negated after 11 bit is shifted in hence the volume is added for 11 cycles and then subtracted for 11 cycles.
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