diff --git a/Makefile.in b/Makefile.in
index 6e4c96ab3..04422581b 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -106,7 +106,7 @@ eval_tree.o expr_synth.o functor.o lexor.o lexor_keyword.o link_const.o \
 load_module.o netlist.o netmisc.o net_assign.o \
 net_design.o net_event.o net_expr.o net_force.o net_func.o \
 net_link.o net_modulo.o net_nex_input.o net_nex_output.o \
-net_proc.o net_scope.o net_udp.o pad_to_width.o \
+net_proc.o net_scope.o net_tran.o net_udp.o pad_to_width.o \
 parse.o parse_misc.o pform.o pform_disciplines.o pform_dump.o pform_types.o \
 set_width.o symbol_search.o sync.o sys_funcs.o \
 verinum.o verireal.o target.o targets.o \
diff --git a/design_dump.cc b/design_dump.cc
index 3c00083a8..1d408ffd8 100644
--- a/design_dump.cc
+++ b/design_dump.cc
@@ -611,6 +611,17 @@ void NetTaskDef::dump(ostream&o, unsigned ind) const
       o << setw(ind) << "" << "endtask" << endl;
 }
 
+void NetTran::dump_node(ostream&o, unsigned ind) const
+{
+      const char*r = resistive_? "r" : "";
+      const char*ifx = enable_==0? "" : enable_>0? "if1" : "if0";
+
+      o << setw(ind) << "" << r << "tran" << ifx << " " << name() << endl;
+
+      dump_node_pins(o, ind+4);
+      dump_obj_attr(o, ind+4);
+}
+
 void NetUDP::dump_node(ostream&o, unsigned ind) const
 {
       o << setw(ind) << "" << "UDP (" << udp_name() << "): ";
diff --git a/elaborate.cc b/elaborate.cc
index abc12b2ca..d4ca9b9df 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -419,7 +419,7 @@ void PGBuiltin::elaborate(Design*des, NetScope*scope) const
       }
 
 	/* Allocate all the netlist nodes for the gates. */
-      NetLogic**cur = new NetLogic*[count];
+      NetNode**cur = new NetNode*[count];
       assert(cur);
 
 	/* Calculate the gate delays from the delay expressions
@@ -659,6 +659,67 @@ void PGBuiltin::elaborate(Design*des, NetScope*scope) const
 		      cur[idx] = new NetLogic(scope, inm, pin_count(),
 					      NetLogic::XOR, instance_width);
 		  break;
+		case TRAN:
+		  if (pin_count() != 2) {
+			cerr << get_fileline() << ": error: Pin count for "
+			     << "tran device." << endl;
+			des->errors += 1;
+			return;
+		  } else {
+			cur[idx] = new NetTran(scope, inm, false, 0);
+		  }
+		  break;
+		case RTRAN:
+		  if (pin_count() != 2) {
+			cerr << get_fileline() << ": error: Pin count for "
+			     << "rtran device." << endl;
+			des->errors += 1;
+			return;
+		  } else {
+			cur[idx] = new NetTran(scope, inm, true, 0);
+			return;
+		  }
+		  break;
+		case TRANIF0:
+		  if (pin_count() != 3) {
+			cerr << get_fileline() << ": error: Pin count for "
+			     << "tranif0 device." << endl;
+			des->errors += 1;
+			return;
+		  } else {
+			cur[idx] = new NetTran(scope, inm, false, -1);
+		  }
+		  break;
+		case RTRANIF0:
+		  if (pin_count() != 3) {
+			cerr << get_fileline() << ": error: Pin count for "
+			     << "rtranif0 device." << endl;
+			des->errors += 1;
+			return;
+		  } else {
+			cur[idx] = new NetTran(scope, inm, true, -1);
+		  }
+		  break;
+		case TRANIF1:
+		  if (pin_count() != 3) {
+			cerr << get_fileline() << ": error: Pin count for "
+			     << "tranif1 device." << endl;
+			des->errors += 1;
+			return;
+		  } else {
+			cur[idx] = new NetTran(scope, inm, false, 1);
+		  }
+		  break;
+		case RTRANIF1:
+		  if (pin_count() != 3) {
+			cerr << get_fileline() << ": error: Pin count for "
+			     << "rtranif1 device." << endl;
+			des->errors += 1;
+			return;
+		  } else {
+			cur[idx] = new NetTran(scope, inm, true, 1);
+		  }
+		  break;
 		default:
 		  cerr << get_fileline() << ": internal error: unhandled "
 			"gate type." << endl;
@@ -670,13 +731,18 @@ void PGBuiltin::elaborate(Design*des, NetScope*scope) const
 		  cur[idx]->attribute(attrib_list[adx].key,
 				      attrib_list[adx].val);
 
-	    cur[idx]->rise_time(rise_time);
-	    cur[idx]->fall_time(fall_time);
-	    cur[idx]->decay_time(decay_time);
+	      /* The logic devices have some uniform processing. Then
+	         all may have output delays and output drive strength. */
+	    if (NetLogic*log = dynamic_cast<NetLogic*> (cur[idx])) {
+		  log->rise_time(rise_time);
+		  log->fall_time(fall_time);
+		  log->decay_time(decay_time);
 
-	    cur[idx]->pin(0).drive0(drive_type(strength0()));
-	    cur[idx]->pin(0).drive1(drive_type(strength1()));
+		  log->pin(0).drive0(drive_type(strength0()));
+		  log->pin(0).drive1(drive_type(strength1()));
+	    }
 
+	    cur[idx]->set_line(*this);
 	    des->add_node(cur[idx]);
       }
 
diff --git a/emit.cc b/emit.cc
index c52190684..079a41c84 100644
--- a/emit.cc
+++ b/emit.cc
@@ -165,6 +165,11 @@ bool NetUserFunc::emit_node(struct target_t*tgt) const
       return tgt->net_function(this);
 }
 
+bool NetTran::emit_node(struct target_t*tgt) const
+{
+      return tgt->tran(this);
+}
+
 bool NetBUFZ::emit_node(struct target_t*tgt) const
 {
       return tgt->bufz(this);
diff --git a/net_tran.cc b/net_tran.cc
new file mode 100644
index 000000000..60be74ad2
--- /dev/null
+++ b/net_tran.cc
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2008 Stephen Williams (steve@icarus.com)
+ *
+ *    This source code is free software; you can redistribute it
+ *    and/or modify it in source code form under the terms of the GNU
+ *    General Public License as published by the Free Software
+ *    Foundation; either version 2 of the License, or (at your option)
+ *    any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+# include "config.h"
+
+# include <iostream>
+
+# include  <typeinfo>
+# include  <cstdlib>
+# include  "compiler.h"
+# include  "netlist.h"
+# include  "netmisc.h"
+# include  "ivl_assert.h"
+
+NetTran::NetTran(NetScope*scope, perm_string n, bool resistive, int enable)
+: NetNode(scope, n, enable? 3 : 2)
+{
+      pin(0).set_dir(Link::PASSIVE); pin(0).set_name(perm_string::literal("A"), 0);
+      pin(1).set_dir(Link::PASSIVE); pin(1).set_name(perm_string::literal("B"), 0);
+      if (enable) {
+	    pin(2).set_dir(Link::INPUT);
+	    pin(2).set_name(perm_string::literal("E"), 0);
+      }
+}
+
+NetTran::~NetTran()
+{
+}
diff --git a/netlist.h b/netlist.h
index 691311301..da6bb196a 100644
--- a/netlist.h
+++ b/netlist.h
@@ -1359,6 +1359,20 @@ class NetSysFunc  : public NetNode {
       const struct sfunc_return_type*def_;
 };
 
+class NetTran  : public NetNode {
+
+    public:
+      NetTran(NetScope*scope, perm_string n, bool resistive, int enable);
+      ~NetTran();
+
+      virtual void dump_node(ostream&, unsigned ind) const;
+      virtual bool emit_node(struct target_t*) const;
+
+    private:
+      bool resistive_;
+      bool enable_;
+};
+
 /* =========
  * There are cases where expressions need to be represented. The
  * NetExpr class is the root of a hierarchy that serves that purpose.
diff --git a/t-dll.cc b/t-dll.cc
index c7c383342..4288f7477 100644
--- a/t-dll.cc
+++ b/t-dll.cc
@@ -1008,6 +1008,13 @@ void dll_target::logic(const NetLogic*net)
       scope_add_logic(scope, obj);
 }
 
+bool dll_target::tran(const NetTran*net)
+{
+      cerr << net->get_fileline() << ": sorry: "
+	   << "trans devices not supported." << endl;
+      return false;
+}
+
 bool dll_target::sign_extend(const NetSignExtend*net)
 {
       struct ivl_lpm_s*obj = new struct ivl_lpm_s;
diff --git a/t-dll.h b/t-dll.h
index 76b2443f5..ae0ce2986 100644
--- a/t-dll.h
+++ b/t-dll.h
@@ -67,6 +67,7 @@ struct dll_target  : public target_t, public expr_scan_t {
       bool bufz(const NetBUFZ*);
       void event(const NetEvent*);
       void logic(const NetLogic*);
+      bool tran(const NetTran*);
       bool ureduce(const NetUReduce*);
       void net_case_cmp(const NetCaseCmp*);
       void udp(const NetUDP*);
diff --git a/target.cc b/target.cc
index 379a91754..e474c7cf7 100644
--- a/target.cc
+++ b/target.cc
@@ -61,6 +61,13 @@ void target_t::logic(const NetLogic*)
 	    "Unhandled logic gate" << endl;
 }
 
+bool target_t::tran(const NetTran*)
+{
+      cerr << "target (" << typeid(*this).name() << "): "
+	   << "TRAN devices not supported." << endl;
+      return false;
+}
+
 bool target_t::bufz(const NetBUFZ*)
 {
       cerr << "target (" << typeid(*this).name() <<  "): "
diff --git a/target.h b/target.h
index c68ffc2f0..d002a9797 100644
--- a/target.h
+++ b/target.h
@@ -86,6 +86,7 @@ struct target_t {
 
 	/* Output a gate (called for each gate) */
       virtual void logic(const NetLogic*);
+      virtual bool tran(const NetTran*);
       virtual bool ureduce(const NetUReduce*); /* unary reduction operator */
       virtual bool bufz(const NetBUFZ*);
       virtual void udp(const NetUDP*);