diff --git a/Storage/Disk/DiskDrive.cpp b/Storage/Disk/DiskDrive.cpp
index eff5a2303..29c49d67c 100644
--- a/Storage/Disk/DiskDrive.cpp
+++ b/Storage/Disk/DiskDrive.cpp
@@ -7,3 +7,14 @@
 //
 
 #include "DiskDrive.hpp"
+
+using namespace Storage;
+
+DiskDrive::DiskDrive(unsigned int clock_rate, unsigned int revolutions_per_minute) :
+	_clock_rate(clock_rate),
+	_revolutions_per_minute(revolutions_per_minute) {}
+
+void DiskDrive::set_expected_bit_length(Time bit_length)
+{
+	_bit_length = bit_length;
+}
diff --git a/Storage/Disk/DiskDrive.hpp b/Storage/Disk/DiskDrive.hpp
index b95f5945b..de4b6a551 100644
--- a/Storage/Disk/DiskDrive.hpp
+++ b/Storage/Disk/DiskDrive.hpp
@@ -10,12 +10,15 @@
 #define DiskDrive_hpp
 
 #include "Disk.hpp"
+#include "DigitalPhaseLockedLoop.hpp"
 
 namespace Storage {
 
-class DiskDrive {
+class DiskDrive: public DigitalPhaseLockedLoop::Delegate {
 	public:
-		DiskDrive(unsigned int clock_rate);
+		DiskDrive(unsigned int clock_rate, unsigned int revolutions_per_minute);
+
+		void set_expected_bit_length(Time bit_length);
 
 		void set_disk(std::shared_ptr<Disk> disk);
 		bool has_disk();
@@ -26,8 +29,17 @@ class DiskDrive {
 		void step(int direction);
 		void set_motor_on(bool motor_on);
 
+		// to satisfy DigitalPhaseLockedLoop::Delegate
+		void digital_phase_locked_loop_output_bit(int value);
+
 	protected:
-		virtual void process_input_event(Track::Event event) = 0;
+		virtual void process_input_bit(int value, unsigned int cycles_since_index_hole) = 0;
+		virtual void process_index_hole() = 0;
+
+	private:
+		Time _bit_length;
+		unsigned int _clock_rate;
+		unsigned int _revolutions_per_minute;
 };
 
 }