diff --git a/state.h b/state.h
new file mode 100644
index 0000000..0c61d80
--- /dev/null
+++ b/state.h
@@ -0,0 +1,24 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "vco.h"
+
+typedef struct {
+	float		clock_bpm;
+	float		vco_freq;
+	vco_mode_t	vco_mode;
+	float		vco_volume;
+	bool		quant_enabled;
+	float		filter_freq;
+	float		filter_resonance;
+	float		env1_attack;
+	float		env1_release;
+	float		env2_attack;
+	float		env2_release;
+	float		reverb_amount;
+	bool		amen_enabled;
+} state_t;
+
+extern state_t state;
+
diff --git a/vco.c b/vco.c
new file mode 100644
index 0000000..1235a89
--- /dev/null
+++ b/vco.c
@@ -0,0 +1,4 @@
+float phase = 0.0f;
+
+float vco(void);
+
diff --git a/vco.h b/vco.h
new file mode 100644
index 0000000..1670bcc
--- /dev/null
+++ b/vco.h
@@ -0,0 +1,11 @@
+#pragma once
+
+typedef enum {
+	VCO_SINE	= 0,
+	VCO_SQUARE	= 1,
+	VCO_TRIANGLE	= 2,
+	VCO_SAW		= 3,
+} vco_mode_t;
+
+float vco(void);
+