documentation updates

add Supervision and OPL4 to 7-systems and 4-instrument
improve wording in C64 and SNES description

doc/4-instrument/README.md

@@ -52,6 +52,7 @@ the following instrument types are available:
 - [MSM5232](msm5232.md) - for use with MSM5232 PSG sound source.
 - [MSM6258](msm6258.md) - for use with MSM6258 sample chip.
 - [MSM6295](msm6295.md) - for use with MSM6295 sample chip.
+- [MultiPCM/OPL4 PCM](multipcm.md) - for use with OPL4's sample part.
 - [Namco 163](n163.md) - for use with Namco 163.
 - [Namco WSG](wsg.md) - for use with Namco WSG wavetable chips, including C15 and C30.
 - [NES](nes.md) - for use with NES.
@@ -79,6 +80,7 @@ the following instrument types are available:
 - [VIC](vic.md) - for use with VIC-20 sound chip.
 - [Virtual Boy](virtual-boy.md) - for use with Virtual Boy.
 - [VRC6](vrc6.md) - for use with VRC6's PSG sound source.
+- [Watara Supervision](watarasv.md) - for use with Watara Supervision.
 - [WonderSwan](wonderswan.md) - for use with WonderSwan's wavetable synthesizer.
 - [YMZ280B](ymz280b.md) - for use with YMZ280B sample chip.
 

doc/7-systems/README.md

@@ -114,9 +114,10 @@ this is the full list of chips that Furnace supports.
 - [VIC](vic20.md)
 - [Virtual Boy](virtual-boy.md)
 - [VRC6](vrc6.md)
+- [Watara Supervision](watarasv.md)
 - [WonderSwan](wonderswan.md)
 - [X1-010](x1-010.md)
-- [Y8950, YM3526, YM3812 and YMF262 (OPL)](opl.md)
+- [Y8950, YM3526, YM3812, YMF262 and YMF278 (OPL)](opl.md)
 - [ESFM](esfm.md)
 - [VRC7 and YM2413 (OPLL)](opll.md)
 - [YM2414 (OPZ)](opz.md)

doc/7-systems/c64.md

@@ -6,7 +6,8 @@ very popular in Europe and mostly due to the demoscene, which stretched the mach
 
 two versions of aforementioned chip exist: 6581 (original chip) and 8580 (improved version with working waveform mixing and somewhat more consistent filter curves).
 
-the 6581 version has a hardware bug that causes a loud click whenever a global volume register is updated. these clicks can be used to produce a crude, virtual fourth 4-bit PCM channel. Furnace supports this with the "Commodore 64 (SID 6581) with software PCM" system. the later 8580 revision fixed this problem, making such PCM nearly inaudible; while other PCM playback methods have been invented, Furnace doesn't support them at the moment.
+the 6581 has a hardware quirk which produces a DC output with its intensity being regulated by the global volume register. this register can be abused to produce a crude, virtual fourth 4-bit PCM channel.
+Furnace supports this with the "Commodore 64 (SID 6581) with software PCM" system. the later 8580 chip fixed this problem, making such PCM nearly inaudible; while other PCM playback methods have been invented, Furnace does not support them at the moment.
 
 ## effects
 

doc/7-systems/opl.md

@@ -85,7 +85,9 @@ afterwards everyone moved to Windows and software mixed PCM streaming...
 
 ## info
 
-these chips use the [FM (OPL)](../4-instrument/fm-opl.md) instrument editor. Y8950 ADPCM uses [Generic Sample](../4-instrument/sample.md) and [ADPCM-B](../4-instrument/adpcm-b.md) instrument editors.
+these chips use the [FM (OPL)](../4-instrument/fm-opl.md) instrument editor.
+Y8950 ADPCM uses [Generic Sample](../4-instrument/sample.md) and [ADPCM-B](../4-instrument/adpcm-b.md) instrument editors.
+OPL4 PCM uses the [MultiPCM](../4-instrument/multipcm.md) instrument editor.
 
 when two channels are joined for 4-op mode, the channel bar will show `4OP` on a bracket tying them together.
 
@@ -102,4 +104,4 @@ additionally, in OPL3:
 
 additionally, in OPL4:
 
-- **RAM Size**: sets the RAM size for sample storage
+- **RAM Size**: sets the RAM size for sample storage.

doc/7-systems/snes.md

@@ -98,7 +98,8 @@ the following options are available in the Chip Manager window:
 - **Dec/Hex**: toggles decimal or hexadecimal mode for the filter settings text entry box to the right.
   - SnesLab provides [echo filter explanations and examples](https://sneslab.net/wiki/FIR_Filter#Uses). their example filter strings can be pasted directly into the filter settings text entry box if set to Hex mode.
 - **Disable Gaussian interpolation**: removes sample interpolation, resulting in crisper but aliased sound. not accurate to hardware.
-- **Anti-click**: reduces clicking by use of hardware volume envelopes.
+- **Anti-click**: reduces clicks in the output by using hardware envelopes to smooth them out.
+  - make sure your samples start on center, or else you will still hear clicks.
 
 ## ADSR
 

doc/7-systems/watarasv.md

@@ -1,19 +1,21 @@
 # Watara Supervision
 
-a failed competitor of Game Boy, straight from Taiwan. released in 1992, it had a tilting screen, $50 price tag, very fast 4 MHz 6502-like CPU, framebuffer graphics and sound capabilities similia to Game Boy.
+a failed competitor of Game Boy, straight from Taiwan. released in 1992, it had a tilting screen, $50 price tag, very fast 4 MHz 6502-like CPU, framebuffer graphics and sound capabilities similar to Game Boy.
+
+these are 2 pulse wave channels (same as on GB), barely working PCM channel and noise channel, also not unlike Game Boy. no hardware envelopes or zombie mode, though.
 
-these are 2 pulse wave channels (same as on GB), barely working PCM channel and noise channel, also not unlike Game Boy. no hardware envelopes or zombie mode, though
 ## effects
 
 - `12xx`: **set duty cycle/noise mode.**
-  - range is `0` to `3 ` for pulses and `0` to `1` for noise.
+  - range is `0` to `3` for pulse and `0` to `1` for noise.
+
 ## info
 
 this chip uses the [Watara Supervision](../4-instrument/watarasv.md) and [Generic Sample](../4-instrument/sample.md) instrument editors.
 
 ### sample info
 
-sample channel is 4-bit DMA channel with 4 frequencies assigned to sample octaves (C2, C3, C4, C5; C, C#, D, D# in furnace respectively). max sample size is 4 kilobytes (8192 samples).
+sample channel is a 4-bit DMA channel with 4 frequencies assigned to sample octaves (C2, C3, C4, C5; C, C#, D, D# in Furnace respectively). max sample size is 4 kilobytes (8192 samples).
 
 ## chip config