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2.6 KiB
2.6 KiB
5E01
a fantasy sound chip created by Euly, based on the Ricoh 2A03, with some improvements:
- a 37.5% duty cycle,
- 32 noise pitches instead of 16, and
- triangle channel becomes a wave channel, with four available waveforms: triangle, saw, sine and square.
effects
11xx
: write to delta modulation counter. range is00
to7F
.- this may be used to attenuate the triangle and noise channels; at
7F
, they will be at about 57% volume. - will not work if a sample is playing.
- this may be used to attenuate the triangle and noise channels; at
12xx
: set duty cycle/noise mode/waveform of channel.- may be
0
to3
for the pulse channels:0
: 12.5%1
: 25%2
: 37.5%3
: 50%
- may be
0
or1
for the noise channel:0
: long (15-bit LFSR, 32767-step)1
: short (9-bit LFSR, 93-step)
- may be
0
to3
for the wave channel:0
: triangle1
: saw2
: square3
: sine
- may be
13xy
: setup sweep up.x
is the time.y
is the shift.- set to
0
to disable it.
14xy
: setup sweep down.x
is the time.y
is the shift.- set to
0
to disable it.
15xx
: set envelope mode.0
: envelope + length counter. volume represents envelope duration.1
: length counter. volume represents output volume.2
: looping envelope. volume represents envelope duration.3
: constant volume. default value. volume represents output volume.- pulse and noise channels only.
- you may need to apply a phase reset (using the macro) to make the envelope effective.
16xx
: set length counter.- see NES for more information.
- this will trigger phase reset.
17xx
: set frame counter mode.0
: 4-step.1
: 5-step.
18xx
: set PCM channel mode.00
: PCM (software).01
: DPCM (hardware).- when in DPCM mode, samples will sound muffled (due to its nature), availables pitches are limited, and loop point is ignored.
19xx
: set triangle linear counter.00
to7F
set the counter.80
and higher halt it.
20xx
: set DPCM frequency.- only works in DPCM mode.
info
this chip uses the NES instrument editor.
chip config
the following options are available in the Chip Manager window:
- Clock rate: sets the rate at which the chip will run.
- DPCM channel mode: allows you to set which mode to use for the DPCM channel.
- DPCM: the default mode, playing 1-bit DPCM samples as supported by the hardware.
- PCM: this mode provides crispier samples by writing the delta counter directly. uses a lot of CPU time in console.