A little more work on docs.

doc/2-interface/components.md

@@ -21,8 +21,7 @@ the following keyboard shortcuts work while on a text field:
 
 these work similar to text fields, but you may only input numbers.
 
-they also usually have `+` and `-` buttons which allow you to increase/decrease the value when clicked (and rapidly do so when holding).
-additionally, Ctrl-clicking these buttons may increase/decrease the value by a coarse amount.
+they often have `+` and `-` buttons which allow you to increase/decrease the value when clicked (and rapidly do so when holding). additionally, Ctrl-clicking these buttons may increase/decrease the value by a coarse amount.
 
 ## sliders
 
@@ -33,6 +32,18 @@ using the scroll wheel while holding Ctrl will change the slider's value by smal
 right-clicking or Ctrl-clicking on a slider (Command-click on macOS) will turn it into a number input field, allowing you to input precise values.
 once you click away it will become a slider again.
 
+## color selectors
+
+this will appear as a small colored square (swatch) anywhere a color may be selected. they may also have numeric entry to the left.
+
+left-click the swatch to pop up a large color panel.
+- click directly within the large square to select saturation and value, and to the rainbow bar on its right to select hue.
+- further to the right there may be "Current" and "Original" swatches. click the "Original" swatch to revert to that color.
+- below that are numeric entry boxes for RGBA (red, green, blue, alpha/opacity) and HSVA (hue, saturation, value, alpha/opacity) formats. click and drag on a number to raise or lower it. double-click to edit it as text. right-click to choose whether numbers are entered as integers between 0 and 255 or decimals between 0.0 and 1.0.
+- below that is a directly editable web-style hexadecimal RGBA color value in a standard text box.
+
+right-click the swatch or its numeric entry boxes to select the color format and numbers in use.
+
 ## windows
 
 ![window](window.png)

doc/4-instrument/psg.md

@@ -9,6 +9,7 @@ the instrument editor for Sega PSG, SMS, and other TI SN76489 derivatives consis
   - `1`: long noise; preset frequencies.
   - `2`: short noise; use channel 3 for frequency.
   - `3`: long noise; use channel 3 for frequency.
+  -  for more info on these, see the [chip documentation](../7-systems/sms.md#info).
 - **Panning**: output for left and right channels.
   - only on Game Gear!
 - **Pitch**: fine pitch.

doc/7-systems/README.md

@@ -89,6 +89,7 @@ this is the full list of chips that Furnace supports.
 - [MultiPCM](multipcm.md)
 - [Namco 163](n163.md)
 - [Namco C140](c140.md)
+- [Namco C219](c219.md)
 - [Namco WSG/C15/C30](namco.md)
 - [Nintendo DS](nds.md)
 - [HuC6280](pce.md)

doc/7-systems/sms.md

@@ -2,8 +2,6 @@
 
 the SN76489 is a relatively simple sound chip made by Texas Instruments. a derivative of it is used in the Sega Master System and Sega Genesis. it has three square wave channels and one noise channel.
 
-the noise channel's default mode uses only 3 preset frequencies. to use the full range of pitches, one can enable a mode which matches the frequency of square wave channel 3. in addition, periodic noise mode can be enabled to create a "thin pulse" tone that sounds four octaves lower than the square wave channels.
-
 the original iteration of the SN76489 used in the TI-99/4A computer, the SN94624, runs at a clock speed of 447 kHz and can only produce square waves as low as approximately 110 Hz, or note A2. later versions of the chip (such as the one in the Master System and Genesis) add an internal divide-by-8 stage and generally run at higher system clock rates to achieve a matching or similar frequency range.
 
 ## SN7 versions
@@ -24,7 +22,7 @@ SN7 was extremely popular due to low cost. therefore, it was cloned and copied t
 
 - `20xy`: **set noise mode.**
   - `x` controls whether to inherit frequency from channel 3.
-    - `0`: use one of 3 preset frequencies (C: A-2; C#: A-3; D: A-4).
+    - `0`: use one of 3 preset frequencies (see info below).
     - `1`: use frequency of channel 3.
   - `y` controls whether to select noise or thin pulse.
     - `0`: thin pulse.
@@ -34,6 +32,8 @@ SN7 was extremely popular due to low cost. therefore, it was cloned and copied t
 
 this chip uses the [SN76489/Sega PSG](../4-instrument/psg.md) instrument editor.
 
+the noise channel's default mode uses only 3 preset frequencies. to use the full range of pitches, one can enable a mode in which the noise channel matches the frequency of square wave channel 3. in addition, periodic noise mode can be enabled to create a "thin pulse" tone that sounds four octaves lower than the square wave channels. for convenience in entering notes, a tracked note of C corresponds to a played note of A or A# in octave 2, C# is octave 3, and D is octave 4.
+
 noise mode macro values:
 - **0**: same as effect `2000`. thin pulse, 3 preset frequencies.
 - **1**: same as effect `2001`. noise, 3 preset frequencies.

doc/9-guides/tuning-samples.md

@@ -13,4 +13,6 @@ for this example, we'll use a sample of a note played at E and recorded at 22050
 - now, using the "Preview sample" button should play the note at C. entering an E in the pattern will now play it at or near E.
 - if the sample still sounds out of tune, adjust "Hz" or "Fine" to bring it in line.
 
-if notes seem "capped" – for example, playing anything over D-6 sounds like a D-6 – those notes exceed the maximum sample playback rate for the chip. the only solution is to use "Resample" to change the sample to a lower rate.
+to find the frequency of a note, open the [tuner](../8-advanced/tuner.md) (window > visualizers > tuner). when sound is played, the tuner will continually update to show the note closest to it. this corresponds to the highest peak shown in the [spectrum analyzer](../8-advanced/spectrum.md) (window > visualizers > spectrum).
+
+if notes seem "capped" – for example, playing anything over D-6 sounds like a D-6 – those notes exceed the maximum sample playback rate for the chip. the only solution is to use "Resample" to change the sample to a lower rate. similarly, if samples sound fine in the editor but out of tune when used in the track, there may be limitations on available playback rates. check the [chip's documentation](../7-systems/README.md) for details.