diff --git a/vvp/README.txt b/vvp/README.txt
index 0281df84c..bba6d9c5e 100644
--- a/vvp/README.txt
+++ b/vvp/README.txt
@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
  *
- *  $Id: README.txt,v 1.74 2005/11/25 17:55:26 steve Exp $
+ *  $Id: README.txt,v 1.75 2006/01/02 05:32:06 steve Exp $
  */
 
 VVP SIMULATION ENGINE
@@ -128,7 +128,8 @@ label is required for functors.
 
 The general syntax of a functor is:
 
-	<label> .functor <type> [ (<delay>) ], symbol_list ;
+	<label> .functor <type>, symbol_list ;
+	<label> .functor <type> [<drive0> <drive1>], symbol_list ;
 
 The symbol list is 4 names of labels of other functors. These connect
 inputs of the functor of the statement to the output of other
@@ -309,7 +310,7 @@ that arrive through them, while .net nodes reduce strength values to
 information really is possible.
 
 The <label> is required and is used to locate the net object that is
-represents. This label does not map to a functor, so only references
+vrepresents. This label does not map to a functor, so only references
 that know they want to access .nets are able to locate the symbol. In
 particular, this includes behavioral %load and %wait instructions. The
 references to net and reg objects are done through the .net label
@@ -320,6 +321,23 @@ The .alias statements do not create new nodes, but instead create net
 names that are aliases of an existing node. This handles special cases
 where a net has different names, possibly in different scopes.
 
+DELAY STATEMENTS:
+
+Delay nodes are structural net delay nodes that carry and manage
+propagation delays. Delay nodes can have fixed delays or variable
+delays. Fixed delay nodes have only the input that is to be
+delayed. The delay amount is given on the node line. Variable delay
+nodes have three extra inputs to receive the rise, fall and decay
+times that are used for delay.
+
+	.delay ( <rise>, <fall>, <decay> ) <input> ;
+	.delay <input>, <rise>, <fall>, <decay> ;
+
+The first form above takes three constant numbers as the initial
+delay, and takes a single input. The second form takes 4 net inputs,
+with the first being the value to delay, and the remaining to be the
+delay values to use.
+
 MEMORY STATEMENTS:
 
 Memories are arrays of words, each word a vvp_vector4_t vector of the
diff --git a/vvp/compile.cc b/vvp/compile.cc
index 09398e859..534c7a088 100644
--- a/vvp/compile.cc
+++ b/vvp/compile.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: compile.cc,v 1.215 2005/11/26 17:16:05 steve Exp $"
+#ident "$Id: compile.cc,v 1.216 2006/01/02 05:32:06 steve Exp $"
 #endif
 
 # include  "arith.h"
@@ -1025,6 +1025,35 @@ void compile_cmp_gt(char*label, long wid, bool signed_flag,
       make_arith(arith, label, argc, argv);
 }
 
+
+void compile_delay(char*label, vvp_delay_t*delay, struct symb_s arg)
+{
+      vvp_net_t*net = new vvp_net_t;
+      vvp_fun_delay*obj = new vvp_fun_delay(net, BIT4_X, *delay);
+      net->fun = obj;
+
+      delete delay;
+
+      input_connect(net, 0, arg.text);
+
+      define_functor_symbol(label, net);
+      free(label);
+}
+
+void compile_delay(char*label, unsigned argc, struct symb_s*argv)
+{
+      vvp_delay_t stub (0, 0, 0);
+      vvp_net_t*net = new vvp_net_t;
+      vvp_fun_delay*obj = new vvp_fun_delay(net, BIT4_X, stub);
+      net->fun = obj;
+
+      inputs_connect(net, argc, argv);
+      free(argv);
+
+      define_functor_symbol(label, net);
+      free(label);
+}
+
 /*
  * Extend nodes.
  */
@@ -1482,6 +1511,9 @@ void compile_param_string(char*label, char*name, char*str, char*value)
 
 /*
  * $Log: compile.cc,v $
+ * Revision 1.216  2006/01/02 05:32:06  steve
+ *  Require explicit delay node from source.
+ *
  * Revision 1.215  2005/11/26 17:16:05  steve
  *  Force instruction that can be indexed.
  *
diff --git a/vvp/compile.h b/vvp/compile.h
index 97195b4e7..d9c630b20 100644
--- a/vvp/compile.h
+++ b/vvp/compile.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: compile.h,v 1.77 2005/11/25 17:55:26 steve Exp $"
+#ident "$Id: compile.h,v 1.78 2006/01/02 05:32:07 steve Exp $"
 #endif
 
 # include  <stdio.h>
@@ -90,8 +90,7 @@ extern void compile_vpi_time_precision(long pre);
  * to existing functors to manage the linking.
  */
 extern void compile_functor(char*label, char*type, unsigned width,
-			    vvp_delay_t*delay, unsigned ostr0,
-			    unsigned ostr1,
+			    unsigned ostr0, unsigned ostr1,
 			    unsigned argc, struct symb_s*argv);
 
 
@@ -108,6 +107,12 @@ extern void compile_concat(char*label, unsigned w0, unsigned w1,
 			   unsigned w2, unsigned w3,
 			   unsigned argc, struct symb_s*argv);
 
+/*
+ * Compile delay nodes of various form.
+ */
+extern void compile_delay(char*label, vvp_delay_t*del, struct symb_s input);
+extern void compile_delay(char*label, unsigned argc, struct symb_s*argv);
+
 /*
  * This is called by the parser to create a part select node.
  * See the PART SELECT STATEMENT section in the README.txt
@@ -337,6 +342,9 @@ extern void compile_alias_real(char*label, char*name,
 
 /*
  * $Log: compile.h,v $
+ * Revision 1.78  2006/01/02 05:32:07  steve
+ *  Require explicit delay node from source.
+ *
  * Revision 1.77  2005/11/25 17:55:26  steve
  *  Put vec8 and vec4 nets into seperate net classes.
  *
diff --git a/vvp/delay.cc b/vvp/delay.cc
index 9f6cf2ce2..f6c9972b7 100644
--- a/vvp/delay.cc
+++ b/vvp/delay.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: delay.cc,v 1.11 2005/11/10 13:27:16 steve Exp $"
+#ident "$Id: delay.cc,v 1.12 2006/01/02 05:32:07 steve Exp $"
 #endif
 
 #include "delay.h"
@@ -25,6 +25,15 @@
 #include <iostream>
 #include <assert.h>
 
+void vvp_delay_t::calculate_min_delay_()
+{
+      min_delay_ = rise_;
+      if (fall_ < min_delay_)
+	    min_delay_ = fall_;
+      if (decay_ < min_delay_)
+	    min_delay_ = decay_;
+}
+
 vvp_delay_t::vvp_delay_t(vvp_time64_t rise, vvp_time64_t fall)
 {
       rise_ = rise;
@@ -39,11 +48,7 @@ vvp_delay_t::vvp_delay_t(vvp_time64_t rise, vvp_time64_t fall, vvp_time64_t deca
       fall_ = fall;
       decay_= decay;
 
-      min_delay_ = rise_;
-      if (fall_ < min_delay_)
-	    min_delay_ = fall_;
-      if (decay_ < min_delay_)
-	    min_delay_ = decay_;
+      calculate_min_delay_();
 }
 
 vvp_delay_t::~vvp_delay_t()
@@ -96,12 +101,38 @@ vvp_time64_t vvp_delay_t::get_min_delay() const
       return min_delay_;
 }
 
+void vvp_delay_t::set_rise(vvp_time64_t val)
+{
+      rise_ = val;
+      if (val < min_delay_)
+	    min_delay_ = val;
+      else
+	    calculate_min_delay_();
+}
+
+void vvp_delay_t::set_fall(vvp_time64_t val)
+{
+      fall_ = val;
+      if (val < min_delay_)
+	    min_delay_ = val;
+      else
+	    calculate_min_delay_();
+}
+
+void vvp_delay_t::set_decay(vvp_time64_t val)
+{
+      decay_ = val;
+      if (val < min_delay_)
+	    min_delay_ = val;
+      else
+	    calculate_min_delay_();
+}
+
 vvp_fun_delay::vvp_fun_delay(vvp_net_t*n, vvp_bit4_t init, const vvp_delay_t&d)
 : net_(n), delay_(d), cur_vec4_(1)
 {
       cur_vec4_.set_bit(0, init);
-      flag_real_ = false;
-      flag_vec4_ = false;
+      run_run_ptr_ = 0;
 }
 
 vvp_fun_delay::~vvp_fun_delay()
@@ -117,6 +148,26 @@ vvp_fun_delay::~vvp_fun_delay()
  */
 void vvp_fun_delay::recv_vec4(vvp_net_ptr_t port, const vvp_vector4_t&bit)
 {
+      if (port.port() > 0) {
+	      // Get the integer value of the bit vector, or 0 if
+	      // there are X or Z bits.
+	    unsigned long val = 0;
+	    vector4_to_value(bit, val);
+
+	    switch (port.port()) {
+		case 1:
+		  delay_.set_rise(val);
+		  return;
+		case 2:
+		  delay_.set_fall(val);
+		  return;
+		case 3:
+		  delay_.set_decay(val);
+		  return;
+	    }
+	    return;
+      }
+
       if (cur_vec4_.eeq(bit))
 	    return;
 
@@ -142,8 +193,27 @@ void vvp_fun_delay::recv_vec4(vvp_net_ptr_t port, const vvp_vector4_t&bit)
       if (use_delay == 0) {
 	    vvp_send_vec4(net_->out, cur_vec4_);
       } else {
-	    flag_vec4_ = true;
-	    flag_real_ = false;
+	    run_run_ptr_ = &vvp_fun_delay::run_run_vec4_;
+	    schedule_generic(this, use_delay, false);
+      }
+}
+
+void vvp_fun_delay::recv_vec8(vvp_net_ptr_t port, vvp_vector8_t bit)
+{
+      assert(port.port() == 0);
+
+      if (cur_vec8_.eeq(bit))
+	    return;
+
+	/* XXXX FIXME: For now, just use the minimum delay. */
+      vvp_time64_t use_delay;
+      use_delay = delay_.get_min_delay();
+
+      cur_vec8_ = bit;
+      if (use_delay == 0) {
+	    vvp_send_vec8(net_->out, cur_vec8_);
+      } else {
+	    run_run_ptr_ = &vvp_fun_delay::run_run_vec8_;
 	    schedule_generic(this, use_delay, false);
       }
 }
@@ -160,26 +230,37 @@ void vvp_fun_delay::recv_real(vvp_net_ptr_t port, double bit)
       if (use_delay == 0) {
 	    vvp_send_real(net_->out, cur_real_);
       } else {
-	    flag_vec4_ = false;
-	    flag_real_ = true;
+	    run_run_ptr_ = &vvp_fun_delay::run_run_real_;
 	    schedule_generic(this, use_delay, false);
       }
 }
 
 void vvp_fun_delay::run_run()
 {
-      if (flag_vec4_) {
-	    vvp_send_vec4(net_->out, cur_vec4_);
-	    flag_vec4_ = false;
-      }
-      if (flag_real_) {
-	    vvp_send_real(net_->out, cur_real_);
-	    flag_real_ = false;
-      }
+      (this->*run_run_ptr_)();
 }
 
+void vvp_fun_delay::run_run_vec4_()
+{
+      vvp_send_vec4(net_->out, cur_vec4_);
+}
+
+void vvp_fun_delay::run_run_vec8_()
+{
+      vvp_send_vec8(net_->out, cur_vec8_);
+}
+
+void vvp_fun_delay::run_run_real_()
+{
+      vvp_send_real(net_->out, cur_real_);
+}
+
+
 /*
  * $Log: delay.cc,v $
+ * Revision 1.12  2006/01/02 05:32:07  steve
+ *  Require explicit delay node from source.
+ *
  * Revision 1.11  2005/11/10 13:27:16  steve
  *  Handle very wide % and / operations using expanded vector2 support.
  *
diff --git a/vvp/delay.h b/vvp/delay.h
index cacf09dba..1ccb7d07f 100644
--- a/vvp/delay.h
+++ b/vvp/delay.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: delay.h,v 1.9 2005/07/06 04:29:25 steve Exp $"
+#ident "$Id: delay.h,v 1.10 2006/01/02 05:32:07 steve Exp $"
 #endif
 
 /*
@@ -43,9 +43,15 @@ class vvp_delay_t {
       vvp_time64_t get_delay(vvp_bit4_t from, vvp_bit4_t to);
       vvp_time64_t get_min_delay() const;
 
+      void set_rise(vvp_time64_t val);
+      void set_fall(vvp_time64_t val);
+      void set_decay(vvp_time64_t val);
+
     private:
       vvp_time64_t rise_, fall_, decay_;
       vvp_time64_t min_delay_;
+
+      void calculate_min_delay_();
 };
 
 /* vvp_fun_delay
@@ -68,23 +74,33 @@ class vvp_fun_delay  : public vvp_net_fun_t, private vvp_gen_event_s {
       ~vvp_fun_delay();
 
       void recv_vec4(vvp_net_ptr_t port, const vvp_vector4_t&bit);
+      void recv_vec8(vvp_net_ptr_t port, vvp_vector8_t bit);
       void recv_real(vvp_net_ptr_t port, double bit);
 	//void recv_long(vvp_net_ptr_t port, long bit);
 
     private:
       virtual void run_run();
 
+
+      void run_run_vec4_();
+      void run_run_vec8_();
+      void run_run_real_();
+
     private:
       vvp_net_t*net_;
       vvp_delay_t delay_;
 
-      bool flag_vec4_, flag_real_;
+      void (vvp_fun_delay::*run_run_ptr_)();
       vvp_vector4_t cur_vec4_;
+      vvp_vector8_t cur_vec8_;
       double cur_real_;
 };
 
 /*
  * $Log: delay.h,v $
+ * Revision 1.10  2006/01/02 05:32:07  steve
+ *  Require explicit delay node from source.
+ *
  * Revision 1.9  2005/07/06 04:29:25  steve
  *  Implement real valued signals and arith nodes.
  *
diff --git a/vvp/lexor.lex b/vvp/lexor.lex
index 5b18080ad..07b6dc873 100644
--- a/vvp/lexor.lex
+++ b/vvp/lexor.lex
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: lexor.lex,v 1.57 2005/11/25 17:55:26 steve Exp $"
+#ident "$Id: lexor.lex,v 1.58 2006/01/02 05:32:07 steve Exp $"
 #endif
 
 # include  "parse_misc.h"
@@ -103,6 +103,7 @@
 ".cmp/gt"   { return K_CMP_GT; }
 ".cmp/gt.s" { return K_CMP_GT_S; }
 ".concat"   { return K_CONCAT; }
+".delay"    { return K_DELAY; }
 ".dff"      { return K_DFF; }
 ".event"    { return K_EVENT; }
 ".event/or" { return K_EVENT_OR; }
@@ -204,6 +205,9 @@ int yywrap()
 
 /*
  * $Log: lexor.lex,v $
+ * Revision 1.58  2006/01/02 05:32:07  steve
+ *  Require explicit delay node from source.
+ *
  * Revision 1.57  2005/11/25 17:55:26  steve
  *  Put vec8 and vec4 nets into seperate net classes.
  *
diff --git a/vvp/logic.cc b/vvp/logic.cc
index 3fe96a2a4..6caeadba6 100644
--- a/vvp/logic.cc
+++ b/vvp/logic.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: logic.cc,v 1.35 2005/09/19 22:47:28 steve Exp $"
+#ident "$Id: logic.cc,v 1.36 2006/01/02 05:32:07 steve Exp $"
 #endif
 
 # include  "logic.h"
@@ -473,7 +473,7 @@ void vvp_fun_xor::run_run()
  */
 
 void compile_functor(char*label, char*type, unsigned width,
-		     vvp_delay_t*delay, unsigned ostr0, unsigned ostr1,
+		     unsigned ostr0, unsigned ostr1,
 		     unsigned argc, struct symb_s*argv)
 {
       vvp_net_fun_t* obj = 0;
@@ -566,29 +566,19 @@ void compile_functor(char*label, char*type, unsigned width,
 	/* If both the strengths are the default strong drive, then
 	   there is no need for a specialized driver. Attach the label
 	   to this node and we are finished. */
-      if (strength_aware || ostr0 == 6 && ostr1 == 6 && delay == 0) {
+      if (strength_aware || ostr0 == 6 && ostr1 == 6) {
 	    define_functor_symbol(label, net);
 	    free(label);
 	    return;
       }
 
       vvp_net_t*net_drv = new vvp_net_t;
-      vvp_net_fun_t*obj_drv;
-
-      if (ostr0 == 6 && ostr1 == 6 && delay != 0) {
-	    obj_drv = new vvp_fun_delay(net_drv, BIT4_X, *delay);
-      } else {
-	    obj_drv = new vvp_fun_drive(BIT4_X, ostr0, ostr1);
-      }
-
+      vvp_net_fun_t*obj_drv = new vvp_fun_drive(BIT4_X, ostr0, ostr1);
       net_drv->fun = obj_drv;
 
 	/* Point the gate to the drive node. */
       net->out = vvp_net_ptr_t(net_drv, 0);
 
-      if (delay)
-	    delete delay;
-
       define_functor_symbol(label, net_drv);
       free(label);
 }
@@ -596,6 +586,9 @@ void compile_functor(char*label, char*type, unsigned width,
 
 /*
  * $Log: logic.cc,v $
+ * Revision 1.36  2006/01/02 05:32:07  steve
+ *  Require explicit delay node from source.
+ *
  * Revision 1.35  2005/09/19 22:47:28  steve
  *  Prevent some excess scheduling of logic propagation events.
  *
diff --git a/vvp/parse.y b/vvp/parse.y
index 96bf63275..8a30495cc 100644
--- a/vvp/parse.y
+++ b/vvp/parse.y
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: parse.y,v 1.79 2005/11/25 17:55:26 steve Exp $"
+#ident "$Id: parse.y,v 1.80 2006/01/02 05:32:07 steve Exp $"
 #endif
 
 # include  "parse_misc.h"
@@ -61,7 +61,7 @@ extern FILE*yyin;
 %token K_ARITH_SUB K_ARITH_SUB_R K_ARITH_SUM
 %token K_CMP_EEQ K_CMP_EQ K_CMP_NEE K_CMP_NE
 %token K_CMP_GE K_CMP_GE_S K_CMP_GT K_CMP_GT_S
-%token K_CONCAT K_DFF
+%token K_CONCAT K_DELAY K_DFF
 %token K_EVENT K_EVENT_OR K_EXTEND_S K_FUNCTOR K_NET K_NET_S K_NET_R
 %token K_NET8 K_NET8_S
 %token K_PARAM K_PART K_PART_PV
@@ -91,7 +91,7 @@ extern FILE*yyin;
 
 %type <argv> argument_opt argument_list
 %type <vpi>  argument
-%type <cdelay> delay
+%type <cdelay> delay delay_opt
 
 %%
 
@@ -131,15 +131,15 @@ statement
      label and a type name, and may have operands. The functor may
      also have a delay specification and output strengths. */
 
-	: T_LABEL K_FUNCTOR T_SYMBOL T_NUMBER delay ',' symbols ';'
-		{ compile_functor($1, $3, $4, $5, 6, 6, $7.cnt, $7.vect); }
+	: T_LABEL K_FUNCTOR T_SYMBOL T_NUMBER ',' symbols ';'
+		{ compile_functor($1, $3, $4, 6, 6, $6.cnt, $6.vect); }
 
-	| T_LABEL K_FUNCTOR T_SYMBOL T_NUMBER delay
+	| T_LABEL K_FUNCTOR T_SYMBOL T_NUMBER
 	          '[' T_NUMBER T_NUMBER ']' ',' symbols ';'
-		{ unsigned str0 = $7;
-		  unsigned str1 = $8;
-		  compile_functor($1, $3, $4, $5, str0, str1,
-				  $11.cnt, $11.vect);
+		{ unsigned str0 = $6;
+		  unsigned str1 = $7;
+		  compile_functor($1, $3, $4, str0, str1,
+				  $10.cnt, $10.vect);
 		}
 
 
@@ -153,7 +153,7 @@ statement
 	| T_LABEL K_UDP_C T_STRING ',' T_NUMBER ',' udp_table ';'
 		{ compile_udp_def(0, $1, $3, $5, 0, $7); }
 
-	| T_LABEL K_UDP T_SYMBOL delay ',' symbols ';'
+	| T_LABEL K_UDP T_SYMBOL delay_opt ',' symbols ';'
 		{ compile_udp_functor($1, $3, $4, $6.cnt, $6.vect); }
 
 
@@ -285,6 +285,17 @@ statement
 		  compile_cmp_gt($1, $3, true, obj.cnt, obj.vect);
 		}
 
+  /* Delay nodes take a set of numbers or a set of inputs. The delay
+     node takes two form, one with an array of constants and a single
+     input, and another with an array of inputs. */
+
+        | T_LABEL K_DELAY delay symbol ';'
+                { compile_delay($1, $3, $4); }
+        | T_LABEL K_DELAY  symbols ';'
+                { struct symbv_s obj = $3;
+		  compile_delay($1, obj.cnt, obj.vect);
+		}
+
   /* DFF nodes have an output and take exactly 4 inputs. */
 
         | T_LABEL K_DFF symbol ',' symbol ',' symbol ',' symbol ';'
@@ -692,10 +703,10 @@ signed_t_number
 	| '-' T_NUMBER { $$ = -$2; }
 	;
 
+delay_opt : delay { $$=$1; } | /* empty */ { $$=0; } ;
+
 delay
-	: /* empty */
-		{ $$ = 0; }
-	| '(' T_NUMBER ')'
+	: '(' T_NUMBER ')'
 		{ $$ = new vvp_delay_t($2, $2); }
 	| '(' T_NUMBER ',' T_NUMBER ')'
 		{ $$ = new vvp_delay_t($2, $4); }
@@ -722,6 +733,9 @@ int compile_design(const char*path)
 
 /*
  * $Log: parse.y,v $
+ * Revision 1.80  2006/01/02 05:32:07  steve
+ *  Require explicit delay node from source.
+ *
  * Revision 1.79  2005/11/25 17:55:26  steve
  *  Put vec8 and vec4 nets into seperate net classes.
  *