Add Toolbar page

Core.md

@@ -19,7 +19,7 @@ After a driver is selected, a particular **device** can be chosen for the driver
 If the device has more than 8 inputs or outputs, you can select the desired range of outputs, offset by a factor of 8.
 
 The **sample rate** is the number of audio samples per second for the audio device to process.
-Note that this rate is different than Rack's internal sample rate set from the toolbar at the top of the screen, which determines the number of samples per second for virtual Rack modules to process.
+Note that this rate is different than Rack's internal sample rate set from the [toolbar](Toolbar.md), which determines the number of samples per second for virtual Rack modules to process.
 If set to different rates, sample rate conversion will occur, resulting in slightly higher CPU usage, slightly less audio fidelity, and slightly more latency.
 
 The **block size** sets the number of samples to store in the audio buffer before releasing to the audio device.

TOC.md

@@ -5,6 +5,7 @@
 - [Quick Start](QuickStart.md)
 - [Installing](Installing.md)
 - [FAQ](FAQ.md)
+- [Toolbar](Toolbar.md)
 - [Core](Core.md)
 - [Bridge](Bridge.md)
 

Toolbar.md

@@ -0,0 +1,16 @@
+# Toolbar
+
+### Power meter
+
+When power meters are enabled, Rack measures the amount of time spent processing each module in *mS* (microsamples).
+In many ways, this is analogous to the limit imposed by hardware modular synthesizers in *mA* (milliamperes).
+
+The total amount of time spent processing all modules must equal **1000 mS**.
+To achieve this, the [Audio](Core.md#audio) module from [Core](Core.md) uses your audio device's high-precision clock to regulate Rack's processing loop, so it idles for some amount of mS until this total is met.
+If the Audio idle time falls to an average of 0 mS over its block size, an audio stutter will occur.
+This can be caused by other modules consuming lots of mS.
+
+### Internal sample rate
+
+Rack advances the state of each module by the duration specified by Rack's internal sample rate.
+A higher sample rate decreases the timestep, resulting in more accurate analog circuit modeling at the expensive of more mS consumed by all modules.