diff --git a/config.default.h b/config.default.h
index e8a20e9..00987eb 100644
--- a/config.default.h
+++ b/config.default.h
@@ -44,6 +44,19 @@
 #define	MOTHERBOARD
 
 
+/** \def KINEMATICS
+
+  This defines the type of kinematics your printer uses. That's essential!
+
+  Valid values (see dda_kinematics.h):
+
+  KINEMATICS_STRAIGHT   Motors move axis directions directly. This is the
+                        traditional type, found in many printers, including
+                        Mendel, Prusa i3, Mendel90, Ormerod, Mantis.
+*/
+#define KINEMATICS KINEMATICS_STRAIGHT
+
+
 /** \def STEPS_PER_M
 	steps per meter ( = steps per mm * 1000 )
 
diff --git a/dda.c b/dda.c
index 70cd176..9e149f4 100644
--- a/dda.c
+++ b/dda.c
@@ -13,6 +13,7 @@
 
 #include	"dda_maths.h"
 #include "preprocessor_math.h"
+#include "dda_kinematics.h"
 #include	"dda_lookahead.h"
 #include	"timer.h"
 #include	"serial.h"
@@ -191,12 +192,10 @@ void dda_create(DDA *dda, TARGET *target) {
     dda->id = idcnt++;
   #endif
 
+  code_axes_to_stepper_axes(&startpoint, target, delta_um, steps);
   for (i = X; i < E; i++) {
     int32_t delta_steps;
 
-    delta_um[i] = (uint32_t)abs32(target->axis[i] - startpoint.axis[i]);
-
-    steps[i] = um_to_steps(target->axis[i], i);
     delta_steps = steps[i] - startpoint_steps.axis[i];
     dda->delta[i] = (uint32_t)abs32(delta_steps);
     startpoint_steps.axis[i] = steps[i];
@@ -217,8 +216,8 @@ void dda_create(DDA *dda, TARGET *target) {
     int32_t delta_steps;
 
     delta_um[E] = (uint32_t)abs32(target->axis[E] - startpoint.axis[E]);
-
     steps[E] = um_to_steps(target->axis[E], E);
+
     delta_steps = steps[E] - startpoint_steps.axis[E];
     dda->delta[E] = (uint32_t)abs32(delta_steps);
     startpoint_steps.axis[E] = steps[E];
diff --git a/dda_kinematics.c b/dda_kinematics.c
new file mode 100644
index 0000000..ebaf8eb
--- /dev/null
+++ b/dda_kinematics.c
@@ -0,0 +1,20 @@
+#include "dda_kinematics.h"
+
+/** \file G-code axis system to stepper motor axis system conversion.
+*/
+
+#include <stdlib.h>
+
+#include "dda_maths.h"
+
+
+void
+carthesian_to_carthesian(TARGET *startpoint, TARGET *target,
+                         axes_uint32_t delta_um, axes_int32_t steps) {
+  enum axis_e i;
+
+  for (i = X; i < E; i++) {
+    delta_um[i] = (uint32_t)labs(target->axis[i] - startpoint->axis[i]);
+    steps[i] = um_to_steps(target->axis[i], i);
+  }
+}
diff --git a/dda_kinematics.h b/dda_kinematics.h
new file mode 100644
index 0000000..96345e3
--- /dev/null
+++ b/dda_kinematics.h
@@ -0,0 +1,41 @@
+#ifndef _DDA_KINEMATICS_H
+#define _DDA_KINEMATICS_H
+
+#include <stdint.h>
+
+#include "dda.h"
+
+#define KINEMATICS_STRAIGHT 1
+//#define KINEMATICS_COREXY 2
+//#define KINEMATICS_SCARA 3
+
+#include "config_wrapper.h"
+
+
+void carthesian_to_carthesian(TARGET *startpoint, TARGET *target,
+                              axes_uint32_t delta_um, axes_int32_t steps);
+
+//void carthesian_to_corexy(TARGET *startpoint, TARGET *target,
+//                          axes_uint32_t delta_um, axes_int32_t steps);
+
+//void carthesian_to_scara(TARGET *startpoint, TARGET *target,
+//                         axes_uint32_t delta_um, axes_int32_t steps);
+
+static void code_axes_to_stepper_axes(TARGET *, TARGET *, axes_uint32_t,
+                                      axes_int32_t)
+                                      __attribute__ ((always_inline));
+inline void code_axes_to_stepper_axes(TARGET *startpoint, TARGET *target,
+                                      axes_uint32_t delta_um,
+                                      axes_int32_t steps) {
+  #if KINEMATICS == KINEMATICS_STRAIGHT
+    carthesian_to_carthesian(startpoint, target, delta_um, steps);
+//  #elif KINEMATICS == KINEMATICS_COREXY
+//    carthesian_to_corexy(startpoint, target, delta_um, steps);
+//  #elif KINEMATICS == KINEMATICS_SCARA
+//    return carthesian_to_scara(startpoint, target, delta_um, steps);
+  #else
+    #error KINEMATICS not defined or unknown, edit your config.h.
+  #endif
+}
+
+#endif /* _DDA_KINEMATICS_H */