diff --git a/Storage/Disk/DiskDrive.cpp b/Storage/Disk/DiskDrive.cpp
index 9c255b988..14f1ae681 100644
--- a/Storage/Disk/DiskDrive.cpp
+++ b/Storage/Disk/DiskDrive.cpp
@@ -49,11 +49,28 @@ bool DiskDrive::get_is_track_zero()
 void DiskDrive::step(int direction)
 {
 	_head_position = std::max(_head_position + direction, 0);
+
+	// TODO: add fractional part to _time_into_track
+
+	// TODO: probably a better implementation of the empty track?
+//	Time offset;
+//	if(_track)
+//	{
+//		Time time_found = _track->seek_to(_time_into_track);
+//		offset = _time_into_track - time_found;
+//	}
+//	else
+//	{
+//		offset = _time_into_track;
+//	}
+
+	// TODO: apply offset
 	set_track();
 }
 
 void DiskDrive::set_track()
 {
+	// TODO: accept and apply offset
 	_track = _disk->get_track_at_position((unsigned int)_head_position);
 	reset_timer();
 	get_next_event();
diff --git a/Storage/Storage.hpp b/Storage/Storage.hpp
index 34f952f8e..7ef85b3a0 100644
--- a/Storage/Storage.hpp
+++ b/Storage/Storage.hpp
@@ -53,6 +53,14 @@ struct Time {
 		return result;
 	}
 
+	inline Time operator-(Time &other)
+	{
+		Time result;
+		result.clock_rate = NumberTheory::least_common_multiple(clock_rate, other.clock_rate);
+		result.length = length * (result.clock_rate / clock_rate) - other.length * (result.clock_rate / other.clock_rate);
+		return result;
+	}
+
 	inline void set_zero()
 	{
 		length = 0;