--- nand.py-
+++ nand.py
@@ -34,15 +34,19 @@
 			other.conn = self
 
 	def set(self, v):
+		v = bool_v(v)
 		if v == self.v:
 			return
 		self.v = v
 		self.dbgout( str_v(v) )
-		if 'O' in self.direc and self.conn:
+		if self.has('O') and self.conn:
 			self.conn.set(v)
-		if 'I' in self.direc and self.parent and hasattr(self.parent, 'update'):
+		if self.has('I') and self.parent and hasattr(self.parent, 'update'):
 			self.enque(self.parent.update)
 
+	def has(self, direc): # direc 'I' or 'O'
+		return direc in self.direc
+
 class Foo(Obj):
 	def __init__(self, parent, latency=None):
 		Obj.__init__(self, parent, 'foo', latency)
@@ -75,6 +79,40 @@
 		v = not ( self.inp_a.v and self.inp_b.v )
 		self.enque( self.out.set, (v,) )
 
+class Joint(Obj):
+	def __init__(self, parent, name='jt', latency=None):
+		Obj.__init__(self, parent, name, latency)
+		self.pins = []
+
+	def connect(self, other_pin):
+		direc = { 'I': 'O', 'O': 'I' }.get(other_pin.direc, 'IO')
+		pin = self.new_pin(direc)
+		pin.connect(other_pin)
+
+	def new_pin(self, direc='IO'):
+		i = len(self.pins)
+		name = 'pin{}_{}'.format(i, direc)
+		pin = Pin(self, name, direc)
+		self.pins.append(pin)
+		return pin
+
+	def update(self):
+		ivs = [ pin.v for pin in self.pins if pin.has('I') ]
+		f = lambda r, v: r if v == None else ( v if r == None else r or v ) # OR
+		v = reduce(f, ivs, None)
+		for pin in self.pins:
+			if pin.has('O'):
+				pin.set(v)
+
+class Lamp(Obj):
+	def __init__(self, parent, name='lamp', latency=None):
+		Obj.__init__(self, parent, name, latency)
+		Pin(self, 'inp', 'I')
+
+	def update(self):
+		msg = str_v( self.inp.v )
+		self.enque( self.dbgout, (msg, True) )
+
 class Sched:
 	def __init__(self):
 		self.que = []
@@ -109,6 +147,9 @@
 def str_v(v):
 	return { True: 'H', False: 'L', None: 'Hi-Z' }.get(v, '?')
 
+def bool_v(v):
+	return {'H': True, 'L': False, 'Hi-Z': None }.get(v, v)
+
 def dbgout(s, always=False):
 	if always or '-v' in sys.argv:
 		print '{} {}'.format( sched.now, s )
@@ -128,14 +169,24 @@
 
 	o.foo.out.connect( o.slow.foo.inp )
 	o.slow.foo.out.connect( o.slow_12.foo.inp )
-	sched.enque( 200, o.foo.out.set, (True,) )
+	sched.enque( 200, o.foo.out.set, ('H',) )
 
 	NAND(o)
-	sched.enque( 300, o.nand.inp_a.set, (False,) )
-	sched.enque( 300, o.nand.inp_b.set, (False,) )
-	sched.enque( 320, o.nand.inp_a.set, (True,) )
-	sched.enque( 340, o.nand.inp_b.set, (True,) )
-	sched.enque( 360, o.nand.inp_a.set, (False,) )
+	sched.enque( 300, o.nand.inp_a.set, ('L',) )
+	sched.enque( 300, o.nand.inp_b.set, ('L',) )
+	sched.enque( 320, o.nand.inp_a.set, ('H',) )
+	sched.enque( 340, o.nand.inp_b.set, ('H',) )
+	sched.enque( 360, o.nand.inp_a.set, ('L',) )
+
+	test1 = Obj(o, 'test1')
+	NAND(test1)
+	Joint(test1)
+	Lamp(test1)
+	o.test1.jt.connect( o.test1.nand.out )
+	o.test1.jt.connect( o.test1.nand.inp_a )
+	o.test1.jt.new_pin('O').connect( o.test1.lamp.inp )
+	sched.enque( 400, o.test1.nand.inp_b.set, ('H',) )
+	sched.enque( 500, o.test1.nand.inp_b.set, ('L',) )
 
 	sched.main_loop()