diff --git a/cumulus/src/plugins/alpha/core2chip/core2chip.py b/cumulus/src/plugins/alpha/core2chip/core2chip.py
index 5196923c..ee4f1e3f 100644
--- a/cumulus/src/plugins/alpha/core2chip/core2chip.py
+++ b/cumulus/src/plugins/alpha/core2chip/core2chip.py
@@ -275,9 +275,15 @@ class IoPad ( object ):
                                               , self.nets[0].coreNet.getName()
                                               , self.padInstanceName ))
             if self.coreToChip.getPadInfo(self.direction) is None:
-                print( WarningMessage( 'IoPad.addNet(): No simple pad in direction {} for "{}", fallback to bi-directional.' \
-                                       .format(netDirectionToStr(self.direction),ioNet.padInstanceName)) )
-                self.direction = IoPad.BIDIR
+                if     (self.direction == IoPad.OUT) \
+                   and (self.coreToChip.getPadInfo(IoPad.TRI_OUT) is not None):
+                    print( WarningMessage( 'IoPad.addNet(): No simple pad in direction {} for "{}", fallback to output tristate.' \
+                                           .format(netDirectionToStr(self.direction),ioNet.padInstanceName)) )
+                    self.direction = IoPad.TRI_OUT
+                else:
+                    print( WarningMessage( 'IoPad.addNet(): No simple pad in direction {} for "{}", fallback to bi-directional.' \
+                                           .format(netDirectionToStr(self.direction),ioNet.padInstanceName)) )
+                    self.direction = IoPad.BIDIR
         elif len(self.nets) == 2:
             if self.direction != IoPad.BIDIR:
                 self.direction = IoPad.TRI_OUT
@@ -321,6 +327,16 @@ class IoPad ( object ):
                 connexions.append( ( self.nets[0].chipIntNet      , padInfo.outputNet ) )
                 connexions.append( ( self.coreToChip.newDummyNet(), padInfo.inputNet  ) )
             connexions.append( ( self.nets[1].chipIntNet, padInfo.enableNet  ) )
+        elif (self.direction == IoPad.TRI_OUT) and (len(self.nets) < 2):
+            self.nets[0].setFlags( IoNet.DoExtNet )
+            self.nets[0].buildNets()
+            if len(self.nets) < 2:
+                enableNet = self.coreToChip.newEnableForNet( self.nets[0] )
+                self.nets.append( self.coreToChip.getIoNet( enableNet ) )
+            self.nets[1].buildNets()
+            connexions.append( ( self.nets[0].chipExtNet, padInfo.padNet    ) )
+            connexions.append( ( self.nets[0].chipIntNet, padInfo.inputNet  ) )
+            connexions.append( ( self.nets[1].chipIntNet, padInfo.enableNet ) )
         else:
             for ioNet in self.nets:
                 if not ioNet.isEnable():
diff --git a/cumulus/src/plugins/alpha/core2chip/libresocio.py b/cumulus/src/plugins/alpha/core2chip/libresocio.py
index 5b5af98c..119b2357 100644
--- a/cumulus/src/plugins/alpha/core2chip/libresocio.py
+++ b/cumulus/src/plugins/alpha/core2chip/libresocio.py
@@ -53,11 +53,13 @@ class CoreToChip ( BaseCoreToChip ):
         with CfgCache() as cfg:
             cfg.chip.useAbstractPads = None
             if not cfg.chip.useAbstractPads:
-                self.ioPadNames = { 'bidir':'IOPadInOut'
-                                  , 'vdd'  :'IOPadVdd'
-                                  , 'vss'  :'IOPadVss'
-                                  , 'iovdd':'IOPadIOVdd'
-                                  , 'iovss':'IOPadIOVss'
+                self.ioPadNames = { 'in'      :'IOPadIn'
+                                  , 'tri_out' :'IOPadOut'
+                                  , 'bidir'   :'IOPadInOut'
+                                  , 'vdd'     :'IOPadVdd'
+                                  , 'vss'     :'IOPadVss'
+                                  , 'iovdd'   :'IOPadIOVdd'
+                                  , 'iovss'   :'IOPadIOVss'
                                   }
         BaseCoreToChip.__init__ ( self, core )
         self.ringNetNames = { 'iovdd' : None
@@ -65,7 +67,13 @@ class CoreToChip ( BaseCoreToChip ):
                             , 'vdd'   : None
                             , 'vss'   : None
                             }
-        self.ioPadInfos   = [ BaseCoreToChip.IoPadInfo( IoPad.BIDIR
+        self.ioPadInfos   = [ BaseCoreToChip.IoPadInfo( IoPad.IN
+                                                      , self.ioPadNames['in']
+                                                      , 'pad', ['s'] )
+                            , BaseCoreToChip.IoPadInfo( IoPad.TRI_OUT
+                                                      , self.ioPadNames['tri_out']
+                                                      , 'pad', ['d', 'de'] )
+                            , BaseCoreToChip.IoPadInfo( IoPad.BIDIR
                                                       , self.ioPadNames['bidir']
                                                       , 'pad', ['s', 'd', 'de'] )
                             ]