diff --git a/doc/2-interface/README.md b/doc/2-interface/README.md
index 7d4300adf..5ad0cd036 100644
--- a/doc/2-interface/README.md
+++ b/doc/2-interface/README.md
@@ -35,6 +35,8 @@ the default layout of Furnace is depicted below.
 - [oscilloscope](../8-advanced/osc.md)
 - [oscilloscope (per channel)](../8-advanced/chanosc.md)
 - [oscilloscope (X-Y)](../8-advanced/xyosc.md)
+- [tuner](../8-advanced/tuner.md)
+- [spectrum](../8-advanced/spectrum.md)
 - [clock](../8-advanced/clock.md)
 - [grooves](../8-advanced/grooves.md)
 - [log viewer](../8-advanced/log-viewer.md)
@@ -45,4 +47,6 @@ the default layout of Furnace is depicted below.
 ## other topics
 
 - [piano/input pad](../8-advanced/piano.md)
+- [reference music player](../8-advanced/refPlayer.md)
+- [multi-ins setup](../8-advanced/multi-ins.md)
 - [settings](settings.md)
diff --git a/doc/8-advanced/README.md b/doc/8-advanced/README.md
index 759737e0e..e4641bbbd 100644
--- a/doc/8-advanced/README.md
+++ b/doc/8-advanced/README.md
@@ -19,6 +19,8 @@ as listed in the "Window" menu:
   - [oscilloscope](../8-advanced/osc.md)
   - [oscilloscope (per-channel)](../8-advanced/chanosc.md)
   - [oscilloscope (X-Y)](../8-advanced/xyosc.md)
+  - [tuner](../8-advanced/tuner.md)
+  - [spectrum](../8-advanced/spectrum.md)
   - volume meter
 - tempo
   - [clock](../8-advanced/clock.md)
@@ -29,6 +31,8 @@ as listed in the "Window" menu:
   - [statistics](../8-advanced/stats.md)
   - [memory composition](../8-advanced/memory-composition.md)
 - [piano/input pad](../8-advanced/piano.md)
+- [reference music player](../8-advanced/refPlayer.md)
+- [multi-ins setup](../8-advanced/multi-ins.md)
 
 other:
 
diff --git a/doc/8-advanced/mixer.md b/doc/8-advanced/mixer.md
index 55beca2a1..03883e6ad 100644
--- a/doc/8-advanced/mixer.md
+++ b/doc/8-advanced/mixer.md
@@ -4,9 +4,9 @@ the "Mixer" dialog provides options for overall sound mixing.
 
 ## "Mixer" tab
 
-![mixer dialog on mixer tab](mixer-mixer.png)
+![mixer dialog on mixer tab](mixer-mixer.png) <!--new image(s) needed!-->
 
-"Master Volume" controls the overall mix.
+**Master Volume** controls the overall mix.
 
 each chip has several options:
 - **Invert**: flips the output wave.
@@ -14,6 +14,15 @@ each chip has several options:
 - **Panning**: left-right sound control.
 - **Front/Rear**: front-read sound control. only useful for setups with four or more speakers.
 
+### Mixer-specific settings <!--in settings-->
+- **Mixer layout**: how the mixer is shown.
+  - **Horizontal**: arranges the "chips"<!--reword!--> horizontally, with vertical volume sliders.
+  - **Vertical**: arranges the "chips"<!--ditto--> vertically, with horizontal volume sliders.
+- **Mixer style**:
+  - **No volume meters**: does not show per-chip volume meters.
+  - **Volume meters separate**: shows per-chip volume meters below or to the right (depending on the layout) of the volume slider.
+  - **Volume meters in volume sliders**: shows per-chip volume meters inside the volume sliders.
+
 ## "Patchbay" tab
 
 ![mixer dialog on patchbay tab](mixer-patchbay.png)
diff --git a/doc/8-advanced/refPlayer.md b/doc/8-advanced/refPlayer.md
new file mode 100644
index 000000000..6677a3d8a
--- /dev/null
+++ b/doc/8-advanced/refPlayer.md
@@ -0,0 +1,6 @@
+# reference music player
+
+the Music Player window is a small audio player that can synchronize with the tracker playback.
+<!--IMAGE
+![reference music player window]()-->
+<!--TODO: the rest-->
diff --git a/doc/8-advanced/spectrum.md b/doc/8-advanced/spectrum.md
new file mode 100644
index 000000000..8a315d8dd
--- /dev/null
+++ b/doc/8-advanced/spectrum.md
@@ -0,0 +1,23 @@
+# spectrum
+
+the Spectrum window shows the frequency spectrum of the audio output.
+
+<!--IMAGE
+![spectrum window]()-->
+
+<!--somehow make this info work-->
+the X scale is in Hertz, and the Y scale is in decibels.
+
+clicking the threeline <!--REPLACE--> button in the top left corner open its configuration.
+- **Mono**: whether to mix all the output for a single graph.
+- **Bins**: number of bins for the FFT calculation.
+---
+- **X Zoom**: how much to zoom the X axis.
+- **X Offset**: how much to move the X axis.
+---
+- **Y Offset**: how much to move the Y axis down.
+---
+- **Show X Grid**: whether to show the X axis grid lines.
+- **Show Y Grid**: whether to show the Y axis grid lines.
+- **Show X Scale**: whether to show the X axis scale.
+- **Show Y Scale**: whether to show the Y axis scale.
\ No newline at end of file
diff --git a/doc/8-advanced/tuner.md b/doc/8-advanced/tuner.md
new file mode 100644
index 000000000..233a09dd0
--- /dev/null
+++ b/doc/8-advanced/tuner.md
@@ -0,0 +1,6 @@
+# tuner
+
+the Tuner window shows the approximate frequency and note of the audio output.
+
+<!-- IMAGE
+![tuner window]()-->