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Update C64 instrument info
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doc/4-instrument/c64.md
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@ -5,15 +5,13 @@ the C64 instrument editor consists of two tabs: "C64" to control various paramet
## C64
- **Waveform**: allows selecting a waveform.
- more than one waveform can be selected at once. in that case logical AND mix of waves will occur.
- more than one waveform can be selected at once. in that case logical AND mix of waves should occur, bit actually a weird bit mixing occurs (due to the hardware flaws; 6581 and 8580 models handle those "combined waves" differently).
- noise is an exception. it cannot be used with any of the other waveforms.
- **Attack**: determines the rising time for the sound. the bigger the value, the slower the attack. (0 to 15).
- **Decay**: determines the diminishing time for the sound. the higher the value, the longer the decay (0 to 15).
- **Sustain**: sets the volume level at which the sound stops decaying and holds steady (0 to 15).
- **Release**: determines the rate at which the sound fades out after note off. the higher the value, the longer the release (0 to 15).
- **Duty**: specifies the width of a pulse wave (0 to 4095).
- **Ring Modulation**: when enabled, the channel's output will be multiplied with the previous channel's.
- **Oscillator Sync**: enables oscillator hard sync. as the previous channel's oscillator finishes a cycle, it resets the period of the channel's oscillator, forcing the latter to have the same base frequency. this can produce a harmonically rich sound, the timbre of which can be altered by varying the synchronized oscillator's frequency.
@ -26,9 +24,8 @@ the C64 instrument editor consists of two tabs: "C64" to control various paramet
- **high**: a high-pass filter. higher cutoff values result in a less "bassy" sound.
- **band**: a band-pass filter. cutoff determines which part of the sound is heard (from bass to treble).
- **ch3off**: mutes channel 3 when enabled. not sure why is this part of the chip's design, but it is.
- Different filter modes can be selected simultaneously, e.g. low+high. The resulting sound would be as if input was passed through lowpass filter and then highpass filter (or vice versa, you get the idea).
- **Volume Macro is Cutoff Macro**: turns the volume macro in the Macros tab into a filter cutoff macro.
- volume control is global (affects entire chip output), hence the option.
- **Absolute Cutoff Macro**: when enabled, the cutoff macro will go from 0 to 2047, and it will be absolute (in other words, control the cutoff directly rather than being relative).
- **Absolute Duty Macro**: when enabled, the duty macro will go from 0 to 4095.
- **Don't test before new note**: this option disables the one-tick hard reset and test bit before a new note.
@ -37,12 +34,21 @@ the C64 instrument editor consists of two tabs: "C64" to control various paramet
- **Volume**: volume sequence.
- warning: volume sequence is global! this means it controls the chip's volume and therefore affects all channels.
- this macro becomes **Cutoff** when the **Volume Macro is Cutoff Macro** option is enabled in the C64 tab.
- **Arpeggio**: pitch sequence.
- **Duty**: pulse width sequence.
- **Waveform**: select the waveform used by instrument.
- **Pitch**: fine pitch.
- **Cutoff**: filter cutoff.
- **Filter mode**: select the filter mode.
- **Resonance**: filter resonance sequence.
- **Special**: ring and oscillator sync selector.
- **Test/Gate**: when on, the test bit is set, which mutes the channel.
- **Special**: ring and oscillator sync selector, as well as:
- **gate bit**:
- set (1) = key on, if previous state was 0 it triggers envelope start/restart, if previous state was 1 does nothing
- reset (0) = key off, if previous state was 1 it triggers envelope release, if previous state was 0 does nothing
- **test bit**:
- set (1) = channel immediately muted (if the channel is a source of ring mod and/or hard sync those stop working until you reset the bit)
- reset (0) = unmute channel, restore ring mod/hard sync functionality described above
- **Attack**: sets envelope attack speed. If you modify attack speed when envelope is in attack phase it immediately changes.
- **Decay**: sets envelope decay speed. If you modify decay speed when envelope is in decay phase it immediately changes.
- **Sustain**: sets envelope sustain level. If you modify sustain level when envelope is in sustain phase it immediately changes, although you can only go down (e.g. 9->8 and 8->8 works, but if you go 8->9 channel immediately mutes itself).
- **Release**: sets envelope release speed. If you modify release speed when envelope is in release phase it immediately changes.