diff --git a/vvp/schedule.cc b/vvp/schedule.cc
index 61723d017..38834d645 100644
--- a/vvp/schedule.cc
+++ b/vvp/schedule.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: schedule.cc,v 1.42 2006/08/06 18:17:00 steve Exp $"
+#ident "$Id: schedule.cc,v 1.43 2006/09/29 01:24:34 steve Exp $"
 #endif
 
 # include  "schedule.h"
@@ -61,6 +61,7 @@ struct event_time_s {
 
       struct event_s*active;
       struct event_s*nbassign;
+      struct event_s*rwsync;
       struct event_s*rosync;
 
       struct event_time_s*next;
@@ -266,7 +267,7 @@ static void signals_revert(void)
  * itself, and the structure is placed in the right place in the
  * queue.
  */
-typedef enum event_queue_e { SEQ_ACTIVE, SEQ_NBASSIGN, SEQ_ROSYNC } event_queue_t;
+typedef enum event_queue_e { SEQ_ACTIVE, SEQ_NBASSIGN, SEQ_RWSYNC, SEQ_ROSYNC } event_queue_t;
 
 static void schedule_event_(struct event_s*cur, vvp_time64_t delay,
 			    event_queue_t select_queue)
@@ -281,6 +282,7 @@ static void schedule_event_(struct event_s*cur, vvp_time64_t delay,
 	    ctim = new struct event_time_s;
 	    ctim->active = 0;
 	    ctim->nbassign = 0;
+	    ctim->rwsync = 0;
 	    ctim->rosync = 0;
 	    ctim->delay = delay;
 	    ctim->next  = 0;
@@ -293,6 +295,7 @@ static void schedule_event_(struct event_s*cur, vvp_time64_t delay,
 	    struct event_time_s*tmp = new struct event_time_s;
 	    tmp->active = 0;
 	    tmp->nbassign = 0;
+	    tmp->rwsync = 0;
 	    tmp->rosync = 0;
 	    tmp->delay = delay;
 	    tmp->next = ctim;
@@ -313,6 +316,7 @@ static void schedule_event_(struct event_s*cur, vvp_time64_t delay,
 		  struct event_time_s*tmp = new struct event_time_s;
 		  tmp->active = 0;
 		  tmp->nbassign = 0;
+		  tmp->rwsync = 0;
 		  tmp->rosync = 0;
 		  tmp->delay = delay;
 		  tmp->next  = prev->next;
@@ -328,6 +332,7 @@ static void schedule_event_(struct event_s*cur, vvp_time64_t delay,
 		  struct event_time_s*tmp = new struct event_time_s;
 		  tmp->active = 0;
 		  tmp->nbassign = 0;
+		  tmp->rwsync = 0;
 		  tmp->rosync = 0;
 		  tmp->delay = delay - ctim->delay;
 		  tmp->next = 0;
@@ -367,6 +372,18 @@ static void schedule_event_(struct event_s*cur, vvp_time64_t delay,
 	    }
 	    break;
 
+	  case SEQ_RWSYNC:
+	    if (ctim->rwsync == 0) {
+		  ctim->rwsync = cur;
+
+	    } else {
+		    /* Put the cur event on the end of the active list. */
+		  cur->next = ctim->rwsync->next;
+		  ctim->rwsync->next = cur;
+		  ctim->rwsync = cur;
+	    }
+	    break;
+
 	  case SEQ_ROSYNC:
 	    if (ctim->rosync == 0) {
 		  ctim->rosync = cur;
@@ -502,14 +519,16 @@ void schedule_set_vector(vvp_net_ptr_t ptr, double bit)
       schedule_event_(cur, 0, SEQ_ACTIVE);
 }
 
-void schedule_generic(vvp_gen_event_t obj, vvp_time64_t delay, bool sync_flag)
+void schedule_generic(vvp_gen_event_t obj, vvp_time64_t delay,
+		      bool sync_flag, bool ro_flag)
 {
       struct generic_event_s*cur = new generic_event_s;
 
       cur->obj = obj;
       cur->val = 0;
 
-      schedule_event_(cur, delay, sync_flag? SEQ_ROSYNC : SEQ_ACTIVE);
+      schedule_event_(cur, delay,
+		      sync_flag? (ro_flag?SEQ_ROSYNC:SEQ_RWSYNC) : SEQ_ACTIVE);
 }
 
 static vvp_time64_t schedule_time;
@@ -566,10 +585,15 @@ void schedule_simulate(void)
 		  ctim->nbassign = 0;
 
 		  if (ctim->active == 0) {
-			sched_list = ctim->next;
-			synch_list = ctim->rosync;
-			delete ctim;
-			continue;
+			ctim->active = ctim->rwsync;
+			ctim->rwsync = 0;
+
+			if (ctim->active == 0) {
+			      sched_list = ctim->next;
+			      synch_list = ctim->rosync;
+			      delete ctim;
+			      continue;
+			}
 		  }
 	    }
 
@@ -608,6 +632,9 @@ void schedule_simulate(void)
 
 /*
  * $Log: schedule.cc,v $
+ * Revision 1.43  2006/09/29 01:24:34  steve
+ *  rwsync callback fixes from Ben Staveley (with modifications.)
+ *
  * Revision 1.42  2006/08/06 18:17:00  steve
  *  Fix typo in initialize of new event_time cell.
  *
diff --git a/vvp/schedule.h b/vvp/schedule.h
index d31a85f71..7f5a808be 100644
--- a/vvp/schedule.h
+++ b/vvp/schedule.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: schedule.h,v 1.27 2006/02/02 02:44:00 steve Exp $"
+#ident "$Id: schedule.h,v 1.28 2006/09/29 01:24:34 steve Exp $"
 #endif
 
 # include  "vthread.h"
@@ -77,12 +77,20 @@ extern void schedule_set_vector(vvp_net_ptr_t ptr, double val);
  * up to the user to allocate/free the vvp_get_event_s object. The
  * object is never referenced by the scheduler after the run method is
  * called.
+ *
+ * The sync_flag is true if this is intended to be a sync event. These
+ * are placed in the stratified event queue after nb assignes. If the
+ * ro_flag is true as well, then it is a Read-only sync event, with
+ * all that means.
+ *
+ * If the sync_flag is false, then the event is ACTIVE, and the
+ * ro_flag is ignored.
  */
 
 typedef struct vvp_gen_event_s *vvp_gen_event_t;
 
 extern void schedule_generic(vvp_gen_event_t obj, vvp_time64_t delay,
-			     bool sync_flag);
+			     bool sync_flag, bool ro_flag =true);
 
 struct vvp_gen_event_s
 {
@@ -134,6 +142,9 @@ extern unsigned long count_event_pool;
 
 /*
  * $Log: schedule.h,v $
+ * Revision 1.28  2006/09/29 01:24:34  steve
+ *  rwsync callback fixes from Ben Staveley (with modifications.)
+ *
  * Revision 1.27  2006/02/02 02:44:00  steve
  *  Allow part selects of memory words in l-values.
  *
diff --git a/vvp/vpi_callback.cc b/vvp/vpi_callback.cc
index a2af6942b..46a250ffd 100644
--- a/vvp/vpi_callback.cc
+++ b/vvp/vpi_callback.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: vpi_callback.cc,v 1.43 2006/03/05 05:45:58 steve Exp $"
+#ident "$Id: vpi_callback.cc,v 1.44 2006/09/29 01:24:34 steve Exp $"
 #endif
 
 /*
@@ -212,16 +212,16 @@ static struct __vpiCallback* make_sync(p_cb_data data, bool readonly_flag)
 
       switch (obj->cb_time.type) {
 	  case vpiSuppressTime:
-	    schedule_generic(cb, 0, readonly_flag);
+	    schedule_generic(cb, 0, true, readonly_flag);
 	    break;
 
 	  case vpiSimTime:
 	      { vvp_time64_t tv = vpip_timestruct_to_time(&obj->cb_time);
 		vvp_time64_t tn = schedule_simtime();
 		if (tv < tn) {
-		      schedule_generic(cb, 0, readonly_flag);
+		      schedule_generic(cb, 0, true, readonly_flag);
 		} else {
-		      schedule_generic(cb, tv - tn, readonly_flag);
+		      schedule_generic(cb, tv - tn, true, readonly_flag);
 		}
 		break;
 	      }
@@ -576,6 +576,9 @@ void vvp_fun_signal_real::get_value(struct t_vpi_value*vp)
 
 /*
  * $Log: vpi_callback.cc,v $
+ * Revision 1.44  2006/09/29 01:24:34  steve
+ *  rwsync callback fixes from Ben Staveley (with modifications.)
+ *
  * Revision 1.43  2006/03/05 05:45:58  steve
  *  Add support for memory value change callbacks.
  *