PageUp and PageDown are the volume knob

The cabinets had no volume control - they ran at unity and left level to an
external amplifier - so a player without that hardware had nowhere to turn
it down but environ.ini and a restart. PageUp and PageDown now step the
master volume by 0.05 while you play, from silent to double, and whatever
you leave it on is written to volume.cfg beside the exe and used from then
on. The environ.ini figure decides where a machine that has never been
touched starts out; the keys are the knob, and a knob stays where it was
left.

Page keys because they produce no typed character, so they cannot collide
with the character-keyed commands the engine already answers to, nothing
else in RP binds them, and they are on every keyboard including tenkeyless.

They are polled rather than read off the key-message path, which is worth
recording because the message path looked like the obvious home for them
and was tried first. RP's keyboard pump only takes WM_KEYUP, WM_SYSKEYUP
and WM_CHAR off the front of the queue, and the front end runs message
loops of its own, so key messages get raced for and lost: six deliberate,
well-spaced presses arrived as two. Fine for the abort chord, useless for
something you tap repeatedly to find a level. Reading key state directly
costs nothing and cannot be dropped. That losses figure is a pre-existing
property of the input path, not something this change introduced, and is
worth knowing before anything else gets bound there.

Builds clean, runs, and does not fire unprompted. The step function itself
is proven - it was driven end to end through the message path before the
switch, stepping the right way, clamping, and persisting. What I could not
test from here is the polling trigger, because Windows would not hand the
game foreground and injecting keys without it would have sprayed them
across whatever else was open.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

MUNGA_L4/L4AUDRND.cpp

@@ -6,6 +6,16 @@
 #include "..\munga\notation.h"
 #include "openal/alc.h"
 
+#include <stdio.h>
+
+//
+// Master volume limits, shared by the startup load and the PgUp/PgDn step.
+// The file sits beside the exe with the other runtime state.
+//
+static const char  kAudioVolumeFile[] = "volume.cfg";
+static const float kAudioVolumeStep   = 0.05f;
+static const float kAudioVolumeMax    = 2.0f;
+
 //
 //#############################################################################
 // L4AudioRenderer
@@ -406,14 +416,33 @@ void
 			{
 				float value = (float)atof(setting);
 
-				if (value >= 0.0f && value <= 4.0f)
+				if (value >= 0.0f && value <= kAudioVolumeMax)
 				{
 					master_volume = value;
-					Tell("Audio master volume set to " << master_volume << "\n");
 				}
 			}
 
+			//
+			// Whatever the player last set with the volume keys wins over the
+			// environ.ini figure: the keys are the amplifier knob, and a knob
+			// stays where it was left.  environ.ini sets where it starts on a
+			// machine that has never been touched.
+			//
+			if (FILE *cfg = fopen(kAudioVolumeFile, "rt"))
+			{
+				float value = -1.0f;
+
+				if (fscanf(cfg, "%f", &value) == 1
+					&& value >= 0.0f && value <= kAudioVolumeMax)
+				{
+					master_volume = value;
+				}
+				fclose(cfg);
+			}
+
+			gRPMasterVolume = master_volume;
 			alListenerf(AL_GAIN, master_volume);
+			Tell("Audio master volume " << (int)(master_volume * 100.0f + 0.5f) << "%\n");
 		}
 
 		//
@@ -1299,6 +1328,51 @@ Logical
 	return resources_available;
 }
 
+//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Master volume ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// The pod ran at unity and left volume to an external amplifier, so the game
+// never had a level control.  Standing in for that amplifier means the player
+// needs to reach it while playing, not only through environ.ini -- hence the
+// PgUp/PgDn binding in L4Application::KeyCommandMessageHandler.
+//
+// Page keys specifically: they produce no typed character, so they cannot
+// collide with any of the engine's character-keyed commands the way '+'/'-'
+// would, they are bound to nothing in any RP layout, and they exist on
+// tenkeyless keyboards.
+//
+float gRPMasterVolume = 1.0f;
+
+void
+	RPAudioMasterVolumeStep(int direction)
+{
+	gRPMasterVolume += (direction > 0) ? kAudioVolumeStep : -kAudioVolumeStep;
+
+	if (gRPMasterVolume < 0.0f)				gRPMasterVolume = 0.0f;
+	if (gRPMasterVolume > kAudioVolumeMax)	gRPMasterVolume = kAudioVolumeMax;
+
+	//
+	// Snap to the step grid so repeated presses cannot drift on float error and
+	// land somewhere that never reads back as a round number.
+	//
+	gRPMasterVolume =
+		(float)((int)(gRPMasterVolume / kAudioVolumeStep + 0.5f)) * kAudioVolumeStep;
+
+	alListenerf(AL_GAIN, gRPMasterVolume);
+
+	//
+	// Persist immediately.  A pod operator setting the level expects it to still
+	// be there after the cabinet is power-cycled, and there is no settings UI to
+	// hang it off.
+	//
+	if (FILE *cfg = fopen(kAudioVolumeFile, "wt"))
+	{
+		fprintf(cfg, "%.2f\n", gRPMasterVolume);
+		fclose(cfg);
+	}
+
+	Tell("Audio master volume " << (int)(gRPMasterVolume * 100.0f + 0.5f) << "%\n");
+}
+
 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ OpenAL source pool ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Sources are expensive to create and destroy and are a HARD per-context