diff --git a/conf/Makefile.lpc21 b/conf/Makefile.lpc21
index 10490baae7..0a0fe26907 100644
--- a/conf/Makefile.lpc21
+++ b/conf/Makefile.lpc21
@@ -26,6 +26,7 @@
 # This is the common Makefile for the arm7-target.
 #
 
+# this should not be needed
 #SRC_ARCH = lpc21
 
 # Define programs and commands.
diff --git a/conf/Makefile.sim b/conf/Makefile.sim
index 1f56471e5b..a5eaf9e4d8 100644
--- a/conf/Makefile.sim
+++ b/conf/Makefile.sim
@@ -1,5 +1,5 @@
 # Hey Emacs, this is a -*- makefile -*-
-# 
+#
 #   $Id$
 #   Copyright (C) 2006 Pascal Brisset, Antoine Drouin
 #
@@ -18,14 +18,15 @@
 # You should have received a copy of the GNU General Public License
 # along with paparazzi; see the file COPYING.  If not, write to
 # the Free Software Foundation, 59 Temple Place - Suite 330,
-# Boston, MA 02111-1307, USA.  
-# 
+# Boston, MA 02111-1307, USA.
+#
 
 #
 # This is the common Makefile for the sim target.
 #
 
-SRC_ARCH = sim
+# this should not be needed
+#SRC_ARCH = sim
 
 ifneq ($(SIM_TYPE),JSBSIM)
 CC = gcc
@@ -145,8 +146,8 @@ $(OBJDIR)/.depend:
 	@echo DEPEND $@
 	$(Q)$(CC) -MM -MG $(CFLAGS) $($(TARGET).srcs) | sed 's|\([^\.]*\.o\)|$(OBJDIR)/\1|' > $@
 
-ifneq ($(MAKECMDGOALS),clean) 
-ifneq ($(MAKECMDGOALS),erase) 
+ifneq ($(MAKECMDGOALS),clean)
+ifneq ($(MAKECMDGOALS),erase)
 -include $(OBJDIR)/.depend
 endif
 endif
diff --git a/sw/airborne/sim/adc_hw.c b/sw/airborne/arch/sim/adc_hw.c
similarity index 100%
rename from sw/airborne/sim/adc_hw.c
rename to sw/airborne/arch/sim/adc_hw.c
diff --git a/sw/airborne/sim/adc_hw.h b/sw/airborne/arch/sim/adc_hw.h
similarity index 100%
rename from sw/airborne/sim/adc_hw.h
rename to sw/airborne/arch/sim/adc_hw.h
diff --git a/sw/airborne/sim/baro_MS5534A.h b/sw/airborne/arch/sim/baro_MS5534A.h
similarity index 100%
rename from sw/airborne/sim/baro_MS5534A.h
rename to sw/airborne/arch/sim/baro_MS5534A.h
diff --git a/sw/airborne/sim/gpio.h b/sw/airborne/arch/sim/gpio.h
similarity index 100%
rename from sw/airborne/sim/gpio.h
rename to sw/airborne/arch/sim/gpio.h
diff --git a/sw/airborne/sim/gps_hw.c b/sw/airborne/arch/sim/gps_hw.c
similarity index 100%
rename from sw/airborne/sim/gps_hw.c
rename to sw/airborne/arch/sim/gps_hw.c
diff --git a/sw/airborne/sim/gps_hw.h b/sw/airborne/arch/sim/gps_hw.h
similarity index 100%
rename from sw/airborne/sim/gps_hw.h
rename to sw/airborne/arch/sim/gps_hw.h
diff --git a/sw/airborne/sim/i2c_hw.c b/sw/airborne/arch/sim/i2c_hw.c
similarity index 100%
rename from sw/airborne/sim/i2c_hw.c
rename to sw/airborne/arch/sim/i2c_hw.c
diff --git a/sw/airborne/sim/i2c_hw.h b/sw/airborne/arch/sim/i2c_hw.h
similarity index 100%
rename from sw/airborne/sim/i2c_hw.h
rename to sw/airborne/arch/sim/i2c_hw.h
diff --git a/sw/airborne/sim/init_hw.h b/sw/airborne/arch/sim/init_hw.h
similarity index 100%
rename from sw/airborne/sim/init_hw.h
rename to sw/airborne/arch/sim/init_hw.h
diff --git a/sw/airborne/sim/interrupt_hw.h b/sw/airborne/arch/sim/interrupt_hw.h
similarity index 100%
rename from sw/airborne/sim/interrupt_hw.h
rename to sw/airborne/arch/sim/interrupt_hw.h
diff --git a/sw/airborne/sim/ivy_transport.c b/sw/airborne/arch/sim/ivy_transport.c
similarity index 100%
rename from sw/airborne/sim/ivy_transport.c
rename to sw/airborne/arch/sim/ivy_transport.c
diff --git a/sw/airborne/sim/ivy_transport.h b/sw/airborne/arch/sim/ivy_transport.h
similarity index 100%
rename from sw/airborne/sim/ivy_transport.h
rename to sw/airborne/arch/sim/ivy_transport.h
diff --git a/sw/airborne/sim/jsbsim_gps.c b/sw/airborne/arch/sim/jsbsim_gps.c
similarity index 100%
rename from sw/airborne/sim/jsbsim_gps.c
rename to sw/airborne/arch/sim/jsbsim_gps.c
diff --git a/sw/airborne/sim/jsbsim_hw.c b/sw/airborne/arch/sim/jsbsim_hw.c
similarity index 100%
rename from sw/airborne/sim/jsbsim_hw.c
rename to sw/airborne/arch/sim/jsbsim_hw.c
diff --git a/sw/airborne/sim/jsbsim_hw.h b/sw/airborne/arch/sim/jsbsim_hw.h
similarity index 100%
rename from sw/airborne/sim/jsbsim_hw.h
rename to sw/airborne/arch/sim/jsbsim_hw.h
diff --git a/sw/airborne/sim/jsbsim_ir.c b/sw/airborne/arch/sim/jsbsim_ir.c
similarity index 100%
rename from sw/airborne/sim/jsbsim_ir.c
rename to sw/airborne/arch/sim/jsbsim_ir.c
diff --git a/sw/airborne/sim/jsbsim_transport.c b/sw/airborne/arch/sim/jsbsim_transport.c
similarity index 100%
rename from sw/airborne/sim/jsbsim_transport.c
rename to sw/airborne/arch/sim/jsbsim_transport.c
diff --git a/sw/airborne/sim/led_hw.c b/sw/airborne/arch/sim/led_hw.c
similarity index 100%
rename from sw/airborne/sim/led_hw.c
rename to sw/airborne/arch/sim/led_hw.c
diff --git a/sw/airborne/sim/led_hw.h b/sw/airborne/arch/sim/led_hw.h
similarity index 100%
rename from sw/airborne/sim/led_hw.h
rename to sw/airborne/arch/sim/led_hw.h
diff --git a/sw/airborne/sim/max1167_hw.c b/sw/airborne/arch/sim/max1167_hw.c
similarity index 100%
rename from sw/airborne/sim/max1167_hw.c
rename to sw/airborne/arch/sim/max1167_hw.c
diff --git a/sw/airborne/sim/max1167_hw.h b/sw/airborne/arch/sim/max1167_hw.h
similarity index 100%
rename from sw/airborne/sim/max1167_hw.h
rename to sw/airborne/arch/sim/max1167_hw.h
diff --git a/sw/airborne/sim/micromag_hw.c b/sw/airborne/arch/sim/micromag_hw.c
similarity index 100%
rename from sw/airborne/sim/micromag_hw.c
rename to sw/airborne/arch/sim/micromag_hw.c
diff --git a/sw/airborne/sim/micromag_hw.h b/sw/airborne/arch/sim/micromag_hw.h
similarity index 100%
rename from sw/airborne/sim/micromag_hw.h
rename to sw/airborne/arch/sim/micromag_hw.h
diff --git a/sw/airborne/sim/ppm_hw.c b/sw/airborne/arch/sim/ppm_hw.c
similarity index 100%
rename from sw/airborne/sim/ppm_hw.c
rename to sw/airborne/arch/sim/ppm_hw.c
diff --git a/sw/airborne/sim/ppm_hw.h b/sw/airborne/arch/sim/ppm_hw.h
similarity index 100%
rename from sw/airborne/sim/ppm_hw.h
rename to sw/airborne/arch/sim/ppm_hw.h
diff --git a/sw/airborne/sim/scp1000_hw.c b/sw/airborne/arch/sim/scp1000_hw.c
similarity index 100%
rename from sw/airborne/sim/scp1000_hw.c
rename to sw/airborne/arch/sim/scp1000_hw.c
diff --git a/sw/airborne/sim/scp1000_hw.h b/sw/airborne/arch/sim/scp1000_hw.h
similarity index 100%
rename from sw/airborne/sim/scp1000_hw.h
rename to sw/airborne/arch/sim/scp1000_hw.h
diff --git a/sw/airborne/sim/servos_nil.h b/sw/airborne/arch/sim/servos_nil.h
similarity index 100%
rename from sw/airborne/sim/servos_nil.h
rename to sw/airborne/arch/sim/servos_nil.h
diff --git a/sw/airborne/sim/sim_adc_generic.c b/sw/airborne/arch/sim/sim_adc_generic.c
similarity index 100%
rename from sw/airborne/sim/sim_adc_generic.c
rename to sw/airborne/arch/sim/sim_adc_generic.c
diff --git a/sw/airborne/sim/sim_ap.c b/sw/airborne/arch/sim/sim_ap.c
similarity index 100%
rename from sw/airborne/sim/sim_ap.c
rename to sw/airborne/arch/sim/sim_ap.c
diff --git a/sw/airborne/sim/sim_baro.c b/sw/airborne/arch/sim/sim_baro.c
similarity index 100%
rename from sw/airborne/sim/sim_baro.c
rename to sw/airborne/arch/sim/sim_baro.c
diff --git a/sw/airborne/sim/sim_gps.c b/sw/airborne/arch/sim/sim_gps.c
similarity index 100%
rename from sw/airborne/sim/sim_gps.c
rename to sw/airborne/arch/sim/sim_gps.c
diff --git a/sw/airborne/sim/sim_ir.c b/sw/airborne/arch/sim/sim_ir.c
similarity index 100%
rename from sw/airborne/sim/sim_ir.c
rename to sw/airborne/arch/sim/sim_ir.c
diff --git a/sw/airborne/sim/sim_jsbsim.c b/sw/airborne/arch/sim/sim_jsbsim.c
similarity index 100%
rename from sw/airborne/sim/sim_jsbsim.c
rename to sw/airborne/arch/sim/sim_jsbsim.c
diff --git a/sw/airborne/sim/sim_uart.c b/sw/airborne/arch/sim/sim_uart.c
similarity index 100%
rename from sw/airborne/sim/sim_uart.c
rename to sw/airborne/arch/sim/sim_uart.c
diff --git a/sw/airborne/sim/sim_uart.h b/sw/airborne/arch/sim/sim_uart.h
similarity index 100%
rename from sw/airborne/sim/sim_uart.h
rename to sw/airborne/arch/sim/sim_uart.h
diff --git a/sw/airborne/sim/sim_uart_hw.c b/sw/airborne/arch/sim/sim_uart_hw.c
similarity index 100%
rename from sw/airborne/sim/sim_uart_hw.c
rename to sw/airborne/arch/sim/sim_uart_hw.c
diff --git a/sw/airborne/sim/spi_hw.c b/sw/airborne/arch/sim/spi_hw.c
similarity index 100%
rename from sw/airborne/sim/spi_hw.c
rename to sw/airborne/arch/sim/spi_hw.c
diff --git a/sw/airborne/sim/spi_hw.h b/sw/airborne/arch/sim/spi_hw.h
similarity index 100%
rename from sw/airborne/sim/spi_hw.h
rename to sw/airborne/arch/sim/spi_hw.h
diff --git a/sw/airborne/sim/sys_time_hw.h b/sw/airborne/arch/sim/sys_time_hw.h
similarity index 100%
rename from sw/airborne/sim/sys_time_hw.h
rename to sw/airborne/arch/sim/sys_time_hw.h
diff --git a/sw/airborne/sim/uart_hw.h b/sw/airborne/arch/sim/uart_hw.h
similarity index 100%
rename from sw/airborne/sim/uart_hw.h
rename to sw/airborne/arch/sim/uart_hw.h