diff --git a/Configuration.h b/Configuration.h
index 87077cd..66ac2f1 100644
--- a/Configuration.h
+++ b/Configuration.h
@@ -58,5 +58,8 @@ Licence: GPL
 #define START_FEED_RATE 200
 #define GCODE_LENGTH 100 // Maximum lenght of internally-generated G Code string
 
+// Movement stuff
+
+#define RING_LENGTH 10
 
 #endif
diff --git a/Move.h b/Move.h
index 80dd925..f789247 100644
--- a/Move.h
+++ b/Move.h
@@ -53,6 +53,64 @@ class DDA
     volatile boolean active;
 };
 
+//*********************************************************************************************
+
+/*
+
+  To call the RingBuffer functions the sequences are:
+  
+  Get:
+  
+    if(ringBuffer->getLock())
+    {
+      if(ringBuffer->Empty())
+      {
+        ringBuffer->releaseLock();
+        // Nothing there - go and do something else...
+      }
+      d = Get();
+      ringBuffer->releaseLock();
+      // Do something with d and don't do another Get until you have finished with d...
+    }
+  
+  Add:
+  
+    if(ringBuffer->getLock())
+    {
+      if(ringBuffer->Full())
+      {
+        ringBuffer->releaseLock();
+        // No room - come back later...
+      }
+      ringBuffer->Add(...);
+      ringBuffer->releaseLock();
+    }
+  
+  
+
+*/
+
+class DDARingBuffer
+{
+  public:
+   DDARingBuffer(Move* m, Platform* p);
+   void Add(float currentPosition[], float targetPosition[], float& u, float& v);
+   DDA* Get();
+   boolean Empty();
+   boolean Full();
+   boolean getLock();
+   void releaseLock();
+   
+  private:
+   Platform* platform;
+   DDA* ring[RING_LENGTH];
+   volatile char addPointer;
+   volatile char getPointer;
+   volatile boolean locked;
+};
+
+//**************************************************************************************************
+
 class Move
 {   
   public:
@@ -81,6 +139,8 @@ class Move
     float extruderStepDistances[(1<<(DRIVES-AXES))]; // NB - limits us to 5 extruders
 };
 
+//********************************************************************************************************
+
 inline boolean DDA::Active()
 {
   return active;
@@ -91,6 +151,70 @@ inline boolean DDA::VelocitiesAltered()
   return velocitiesAltered;
 }
 
+//*****************************************************************************************************
+
+inline boolean DDARingBuffer::getLock()
+{
+  if(locked)
+    return false;
+  locked = true;
+  return true;
+}
+
+inline void DDARingBuffer::releaseLock()
+{
+  if(!locked)
+    platform->Message(HOST_MESSAGE, "Attempt to unlock already unlocked ring buffer.\n");
+  locked = false;
+  return;
+}
+
+inline void DDARingBuffer::Add(float currentPosition[], float targetPosition[], float& u, float& v)
+{    
+  if(Full())
+  {
+    platform->Message(HOST_MESSAGE, "Attempt to overfill ring buffer.\n");
+    return;
+  }
+
+  ring[addPointer]->Init(currentPosition, targetPosition, u, v);
+  addPointer++;
+  if(addPointer >= RING_LENGTH)
+    addPointer = 0;
+}
+
+inline DDA* DDARingBuffer::Get()
+{
+  if(Empty())
+  {
+    platform->Message(HOST_MESSAGE, "Attempt to use empty ring buffer.\n");
+    return ring[getPointer]; // Safer than NULL
+  }
+  DDA* d = ring[getPointer];
+  getPointer++;
+  if(getPointer >= RING_LENGTH)
+    getPointer = 0;
+  return d;
+}
+
+inline boolean DDARingBuffer::Empty()
+{
+  return getPointer == addPointer;
+}
+
+// Leave a gap of 2 as the last Get result may still be being processed
+
+inline boolean DDARingBuffer::Full()
+{
+  if(getPointer == 0)
+    return addPointer == RING_LENGTH - 2;
+  if(getPointer == 1)
+    return addPointer == RING_LENGTH - 1;    
+  return addPointer == getPointer - 2;
+}
+
+//**********************************************************************************************
+
 inline void Move::Interrupt()
 {
   dda->Step(true);
diff --git a/Move.ino b/Move.ino
index 29f6caf..be967a6 100644
--- a/Move.ino
+++ b/Move.ino
@@ -414,3 +414,16 @@ void DDA::Step(boolean noTest)
   if(!active && noTest)           //???
     platform->SetInterrupt(-1);
 }
+
+//****************************************************************************************************
+
+DDARingBuffer::DDARingBuffer(Move* m, Platform* p)
+{
+  platform = p;
+  for(addPointer = 0; addPointer < RING_LENGTH; addPointer++)
+   ring[addPointer] = new DDA(m, p);
+  addPointer = 0;
+  getPointer = 0;
+  locked = false; 
+}
+
diff --git a/RepRapFirmware.ino b/RepRapFirmware.ino
index a823f77..ee045c8 100644
--- a/RepRapFirmware.ino
+++ b/RepRapFirmware.ino
@@ -100,6 +100,10 @@ void RepRap::Spin()
   heat->Spin();
 }
 
+// This function is never normally called.  It is a test to time
+// the interrupt function.  To activate it, uncomment the line that calls
+// this in Platform.ino.
+
 void RepRap::InterruptTime()
 {
   char buffer[50];
@@ -125,6 +129,9 @@ void RepRap::InterruptTime()
 
 // Utilities and storage not part of any class
 
+
+// Float to a string.
+
 static long precision[] = {0,10,100,1000,10000,100000,1000000,10000000,100000000};
 
 char* ftoa(char *a, const float& f, int prec)