diff --git a/configure/os/CONFIG.Common.darwin-fat b/configure/os/CONFIG.Common.darwin-fat
new file mode 100644
index 000000000..29724eebf
--- /dev/null
+++ b/configure/os/CONFIG.Common.darwin-fat
@@ -0,0 +1,22 @@
+# CONFIG.Common.darwin-fat
+#
+# $Id$
+# This file is maintained by the build community.
+#
+# Definitions for darwin-fat target builds
+# Sites may override these definitions in CONFIG_SITE.Common.darwin-fat
+#-------------------------------------------------------
+
+#
+# Set architecture-specific information
+#
+ARCH_CLASS = fat
+
+#
+# Universal binary support
+#
+OP_SYS_CFLAGS += -isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc
+OP_SYS_LDFLAGS += -Wl,-syslibroot,/Developer/SDKs/MacOSX10.4u.sdk -arch i386 -arch ppc
+
+# Include definitions common to all Darwin targets
+include $(CONFIG)/os/CONFIG.darwinCommon.darwinCommon
diff --git a/configure/os/CONFIG.Common.darwin-ppc b/configure/os/CONFIG.Common.darwin-ppc
index 3ce4c604f..7ac7c8a01 100644
--- a/configure/os/CONFIG.Common.darwin-ppc
+++ b/configure/os/CONFIG.Common.darwin-ppc
@@ -7,52 +7,10 @@
 # Sites may override these definitions in CONFIG_SITE.Common.darwin-ppc
 #-------------------------------------------------------
 
-# Include definitions common to all Unix targets
-include $(CONFIG)/os/CONFIG.Common.UnixCommon
-
 #
-# Set OS-specific information
+# Architecture-specific information
 #
-OS_CLASS = Darwin
 ARCH_CLASS = ppc
 
-#
-# Special flags for Darwin
-#   No common blocks (as required when using shared libraries)
-#
-OP_SYS_CFLAGS += -fno-common
-
-#
-# Don't try to use precompiled headers when converting sequencer files
-#
-CPPSNCFLAGS += -no-cpp-precomp
-
-#
-# Darwin os definition
-#
-OP_SYS_CPPFLAGS += -Ddarwin
-
-#
-# The following two definitions enable the use of DarwinPorts packages.
-
-#
-OP_SYS_INCLUDES += -I/opt/local/include
-# dir/firstword/wildcard used to avoid warning -L: directory name (...) does not exist
-OP_SYS_LDFLAGS +=  $(addprefix -L,$(dir $(firstword $(wildcard /opt/local/lib/*))))
-
-#
-# The following two definitions enable the use of Fink packages.
-#
-OP_SYS_INCLUDES += -I/sw/include
-# dir/firstword/wildcard used to avoid warning -L: directory name (...) does not exist
-OP_SYS_LDFLAGS +=  $(addprefix -L,$(dir $(firstword $(wildcard /sw/lib/*))))
-
-#
-# Libraries for command-line editing.
-#
-LDLIBS_READLINE = -lreadline
-
-#
-# Command-line input support
-#
-COMMANDLINE_LIBRARY=READLINE
+# Include definitions common to all Darwin targets
+include $(CONFIG)/os/CONFIG.darwinCommon.darwinCommon
diff --git a/configure/os/CONFIG.Common.darwin-x86 b/configure/os/CONFIG.Common.darwin-x86
new file mode 100644
index 000000000..e34dce1dd
--- /dev/null
+++ b/configure/os/CONFIG.Common.darwin-x86
@@ -0,0 +1,16 @@
+# CONFIG.Common.darwin-x86
+#
+# $Id$
+# This file is maintained by the build community.
+#
+# Definitions for darwin-x86 target builds
+# Sites may override these definitions in CONFIG_SITE.Common.darwin-x86
+#-------------------------------------------------------
+
+#
+# Architecture-specific information
+#
+ARCH_CLASS = x86
+
+# Include definitions common to all Darwin targets
+include $(CONFIG)/os/CONFIG.darwinCommon.darwinCommon
diff --git a/configure/os/CONFIG.darwin-fat.Common b/configure/os/CONFIG.darwin-fat.Common
new file mode 100644
index 000000000..184cd1b29
--- /dev/null
+++ b/configure/os/CONFIG.darwin-fat.Common
@@ -0,0 +1,11 @@
+# CONFIG.darwin-fat.Common
+#
+# $Id$
+# This file is maintained by the build community.
+#
+# Definitions for darwin-fat host builds
+# Sites may override these definitions in CONFIG_SITE.darwin-fat.Common
+#-------------------------------------------------------
+
+#Include definitions common to unix hosts
+include $(CONFIG)/os/CONFIG.UnixCommon.Common
diff --git a/configure/os/CONFIG.darwin-x86.Common b/configure/os/CONFIG.darwin-x86.Common
new file mode 100644
index 000000000..6d2ac9c36
--- /dev/null
+++ b/configure/os/CONFIG.darwin-x86.Common
@@ -0,0 +1,11 @@
+# CONFIG.darwin-x86.Common
+#
+# $Id$
+# This file is maintained by the build community.
+#
+# Definitions for darwin-x86 host builds
+# Sites may override these definitions in CONFIG_SITE.darwin-x86.Common
+#-------------------------------------------------------
+
+#Include definitions common to unix hosts
+include $(CONFIG)/os/CONFIG.UnixCommon.Common
diff --git a/configure/os/CONFIG.darwinCommon.darwinCommon b/configure/os/CONFIG.darwinCommon.darwinCommon
new file mode 100644
index 000000000..15e056a23
--- /dev/null
+++ b/configure/os/CONFIG.darwinCommon.darwinCommon
@@ -0,0 +1,101 @@
+# CONFIG.Common.darwinCommon
+#
+# $Id$
+# This file is maintained by the build community.
+#
+# Definitions for darwin target builds
+# Sites may override these definitions in CONFIG_SITE.Common.darwin-<arch>
+#-------------------------------------------------------
+
+# Include definitions common to all Unix targets
+include $(CONFIG)/os/CONFIG.Common.UnixCommon
+
+#
+# Set OS-specific information
+#
+OS_CLASS = Darwin
+
+#
+# Special flags for Darwin
+#   No common blocks (as required when using shared libraries)
+#
+OP_SYS_CFLAGS += -fno-common
+
+#
+# Don't try to use precompiled headers when converting sequencer files
+#
+CPPSNCFLAGS += -no-cpp-precomp
+
+#
+# Darwin os definition
+#
+OP_SYS_CPPFLAGS += -Ddarwin
+
+#
+# Always compile in debugging symbol table information
+#
+OPT_CFLAGS_YES += -g
+OPT_CXXFLAGS_YES += -g
+
+#
+# The following two definitions enable the use of DarwinPorts packages.
+#
+OP_SYS_INCLUDES += -I/opt/local/include
+# dir/firstword/wildcard used to avoid warning -L: directory name (...) does not exist
+OP_SYS_LDFLAGS +=  $(addprefix -L,$(dir $(firstword $(wildcard /opt/local/lib/*))))
+
+#
+# The following two definitions enable the use of Fink packages.
+#
+OP_SYS_INCLUDES += -I/sw/include
+# dir/firstword/wildcard used to avoid warning -L: directory name (...) does not exist
+OP_SYS_LDFLAGS +=  $(addprefix -L,$(dir $(firstword $(wildcard /sw/lib/*))))
+
+#
+# Libraries for command-line editing.
+#
+LDLIBS_READLINE = -lreadline
+
+#
+# Command-line input support
+#
+COMMANDLINE_LIBRARY=READLINE
+
+# Include common gnu compiler definitions
+include $(CONFIG)/CONFIG.gnuCommon
+
+GNU_DIR = /usr
+
+CC = $(GNU_BIN)/cc
+CCC = $(GNU_BIN)/c++
+
+#
+# Darwin shared libraries
+#
+SHRLIB_VERSION = $(EPICS_VERSION).$(EPICS_REVISION).$(EPICS_MODIFICATION)
+SHRLIB_LDFLAGS = -dynamiclib -flat_namespace -undefined suppress \
+       -install_name $(firstword $(SHRLIB_SEARCH_FULLPATHDIRS))/$@ \
+       -compatibility_version $(EPICS_VERSION).$(EPICS_REVISION) \
+       -current_version $(SHRLIB_VERSION)
+SHRLIB_SUFFIX = .$(SHRLIB_VERSION).dylib
+
+LOADABLE_SHRLIB_LDFLAGS = -bundle -flat_namespace -undefined suppress
+
+#
+# Position-independent code is the default on Darwin.
+#
+CODE_CFLAGS = 
+CODE_CXXFLAGS = 
+
+#
+# Add support for Objective-C source
+#
+vpath %.m $(USR_VPATH) $(ALL_SRC_DIRS)
+%.o: %.m
+	$(COMPILE.c) -c $<
+
+#
+# Pedantic produces way too many unnecessary messages
+#
+CONFORM_CFLAGS_STRICT=-ansi
+CONFORM_CXXFLAGS_STRICT=-ansi
diff --git a/configure/os/CONFIG_SITE.darwin-ppc.Common b/configure/os/CONFIG_SITE.darwin-ppc.Common
index 84d9f7b23..732d753fb 100644
--- a/configure/os/CONFIG_SITE.darwin-ppc.Common
+++ b/configure/os/CONFIG_SITE.darwin-ppc.Common
@@ -6,4 +6,4 @@
 # Site override definitions for darwin-ppc host builds
 #-------------------------------------------------------
 
-# CROSS_COMPILER_TARGET_ARCHS = RTEMS-uC5282
+CROSS_COMPILER_TARGET_ARCHS = RTEMS-uC5282 RTEMS-mvme5500  RTEMS-mvme2100