diff --git a/t-dll-expr.cc b/t-dll-expr.cc
index b88d0ee6d..1e4efd32e 100644
--- a/t-dll-expr.cc
+++ b/t-dll-expr.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT) & !defined(macintosh)
-#ident "$Id: t-dll-expr.cc,v 1.22 2002/01/28 00:52:41 steve Exp $"
+#ident "$Id: t-dll-expr.cc,v 1.23 2002/04/14 02:56:19 steve Exp $"
 #endif
 
 # include "config.h"
@@ -362,13 +362,17 @@ void dll_target::expr_unary(const NetEUnary*net)
 
       expr_ = (ivl_expr_t)calloc(1, sizeof(struct ivl_expr_s));
       expr_->type_ = IVL_EX_UNARY;
-      expr_->width_= net->expr_width();
+      expr_->width_ = net->expr_width();
+      expr_->signed_ = net->has_sign()? 1 : 0;
       expr_->u_.unary_.op_ = net->op();
       expr_->u_.unary_.sub_ = sub;
 }
 
 /*
  * $Log: t-dll-expr.cc,v $
+ * Revision 1.23  2002/04/14 02:56:19  steve
+ *  Support signed expressions through to VPI.
+ *
  * Revision 1.22  2002/01/28 00:52:41  steve
  *  Add support for bit select of parameters.
  *  This leads to a NetESelect node and the
diff --git a/tgt-vvp/vvp_process.c b/tgt-vvp/vvp_process.c
index 12f1019c0..052aa2595 100644
--- a/tgt-vvp/vvp_process.c
+++ b/tgt-vvp/vvp_process.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: vvp_process.c,v 1.52 2002/01/11 05:23:05 steve Exp $"
+#ident "$Id: vvp_process.c,v 1.53 2002/04/14 02:56:19 steve Exp $"
 #endif
 
 # include  "vvp_priv.h"
@@ -895,7 +895,8 @@ static int show_system_task_call(ivl_statement_t net)
 		  break;
 	    }
 	    assert(veci < vecs);
-	    fprintf(vvp_out, ", T<%u,%u>", vec[veci].base, vec[veci].wid);
+	    fprintf(vvp_out, ", T<%u,%u,%s>", vec[veci].base,
+		    vec[veci].wid, ivl_expr_signed(expr)? "s" : "u");
 	    veci++;
       }
       
@@ -1102,6 +1103,9 @@ int draw_func_definition(ivl_scope_t scope)
 
 /*
  * $Log: vvp_process.c,v $
+ * Revision 1.53  2002/04/14 02:56:19  steve
+ *  Support signed expressions through to VPI.
+ *
  * Revision 1.52  2002/01/11 05:23:05  steve
  *  Handle certain special cases of stime.
  *
diff --git a/vvp/compile.cc b/vvp/compile.cc
index f45a9bba7..2b003e8ae 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
  */
 #if !defined(WINNT)
-#ident "$Id: compile.cc,v 1.122 2002/03/18 00:19:34 steve Exp $"
+#ident "$Id: compile.cc,v 1.123 2002/04/14 02:56:19 steve Exp $"
 #endif
 
 # include  "arith.h"
@@ -354,10 +354,31 @@ bool vpi_handle_resolv_list_s::resolve(bool mes)
 	    // check for thread vector  T<base,wid>
 	    unsigned base, wid;
 	    unsigned n;
+	    char ss[32];
 	    if (2 <= sscanf(label, "T<%u,%u>%n", &base, &wid, &n) 
 		&& n == strlen(label)) {
-		  val.ptr = vpip_make_vthr_vector(base, wid);
+		  val.ptr = vpip_make_vthr_vector(base, wid, false);
 		  sym_set_value(sym_vpi, label, val);
+
+	    } else if (3 <= sscanf(label, "T<%u,%u,%[su]>%n", &base,
+				   &wid, ss, &n) 
+		       && n == strlen(label)) {
+
+		  bool signed_flag = false;
+		  for (char*fp = ss ;  *fp ;  fp += 1) switch (*fp) {
+		      case 's':
+			signed_flag = true;
+			break;
+		      case 'u':
+			signed_flag = false;
+			break;
+		      default:
+			break;
+		  }
+
+		  val.ptr = vpip_make_vthr_vector(base, wid, signed_flag);
+		  sym_set_value(sym_vpi, label, val);
+
 	    }
       }
 
@@ -1387,6 +1408,9 @@ vvp_ipoint_t debug_lookup_functor(const char*name)
 
 /*
  * $Log: compile.cc,v $
+ * Revision 1.123  2002/04/14 02:56:19  steve
+ *  Support signed expressions through to VPI.
+ *
  * Revision 1.122  2002/03/18 00:19:34  steve
  *  Add the .ufunc statement.
  *
diff --git a/vvp/vpi_priv.h b/vvp/vpi_priv.h
index 8a256a979..101688174 100644
--- a/vvp/vpi_priv.h
+++ b/vvp/vpi_priv.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: vpi_priv.h,v 1.28 2002/02/03 01:01:51 steve Exp $"
+#ident "$Id: vpi_priv.h,v 1.29 2002/04/14 02:56:19 steve Exp $"
 #endif
 
 # include  "vpi_user.h"
@@ -195,7 +195,7 @@ vpiHandle vpip_make_dec_const(int value);
  *  thread. 
  */
 
-vpiHandle vpip_make_vthr_vector(unsigned base, unsigned wid);
+vpiHandle vpip_make_vthr_vector(unsigned base, unsigned wid, bool signed_flag);
 
 /*
  * This function is called before any compilation to load VPI
@@ -268,6 +268,9 @@ extern unsigned vpip_bits_to_dec_str(const unsigned char *bits,
 
 /*
  * $Log: vpi_priv.h,v $
+ * Revision 1.29  2002/04/14 02:56:19  steve
+ *  Support signed expressions through to VPI.
+ *
  * Revision 1.28  2002/02/03 01:01:51  steve
  *  Use Larrys bits-to-decimal-string code.
  *
diff --git a/vvp/vpi_vthr_vector.cc b/vvp/vpi_vthr_vector.cc
index 28cb07c18..852de0a92 100644
--- a/vvp/vpi_vthr_vector.cc
+++ b/vvp/vpi_vthr_vector.cc
@@ -18,7 +18,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: vpi_vthr_vector.cc,v 1.5 2002/01/10 01:54:04 steve Exp $"
+#ident "$Id: vpi_vthr_vector.cc,v 1.6 2002/04/14 02:56:19 steve Exp $"
 #endif
 
 /*
@@ -39,6 +39,7 @@ struct __vpiVThrVec {
       struct __vpiHandle base;
       unsigned short bas;
       unsigned short wid;
+      unsigned signed_flag : 1;
       char *name;
 };
 
@@ -85,7 +86,7 @@ static int vthr_vec_get(int code, vpiHandle ref)
       switch (code) {
 
 	  case vpiSigned:
-	    return 0;
+	    return rfp->signed_flag;
 
 	  case vpiSize:
 	    return rfp->wid;
@@ -115,51 +116,11 @@ static char buf[4096];
 
 static void vthr_vec_DecStrVal(struct __vpiVThrVec*rfp, s_vpi_value*vp)
 {
-      unsigned long val = 0;
-      unsigned count_x = 0, count_z = 0;
+      unsigned char*bits = new unsigned char[rfp->wid];
+      for (unsigned idx = 0 ;  idx < rfp->wid ;  idx += 1)
+	    bits[idx] = get_bit(rfp, idx);
 
-      for (unsigned idx = 0 ;  idx < rfp->wid ;  idx += 1) {
-	    val *= 2;
-	    switch (get_bit(rfp, rfp->wid-idx-1)) {
-		case 0:
-		  break;
-		case 1:
-		  val += 1;
-		  break;
-		case 2:
-		  count_x += 1;
-		  break;
-		case 3:
-		  count_z += 1;
-		  break;
-	    }
-      }
-
-      if (count_x == rfp->wid) {
-	    buf[0] = 'x';
-	    buf[1] = 0;
-	    return;
-      }
-
-      if (count_x > 0) {
-	    buf[0] = 'X';
-	    buf[1] = 0;
-	    return;
-      }
-
-      if (count_z == rfp->wid) {
-	    buf[0] = 'z';
-	    buf[1] = 0;
-	    return;
-      }
-
-      if (count_z > 0) {
-	    buf[0] = 'Z';
-	    buf[1] = 0;
-	    return;
-      }
-
-      sprintf(buf, "%lu", val);
+      vpip_bits_to_dec_str(bits, rfp->wid, buf, sizeof buf, rfp->signed_flag);
 }
 
 static void vthr_vec_StringVal(struct __vpiVThrVec*rfp, s_vpi_value*vp)
@@ -370,13 +331,14 @@ static const struct __vpirt vpip_vthr_const_rt = {
  * Construct a vpiReg object. Give the object specified dimensions,
  * and point to the specified functor for the lsb.
  */
-vpiHandle vpip_make_vthr_vector(unsigned base, unsigned wid)
+vpiHandle vpip_make_vthr_vector(unsigned base, unsigned wid, bool signed_flag)
 {
       struct __vpiVThrVec*obj = (struct __vpiVThrVec*)
 	    malloc(sizeof(struct __vpiVThrVec));
       obj->base.vpi_type = &vpip_vthr_const_rt;
       obj->bas = base;
       obj->wid = wid;
+      obj->signed_flag = signed_flag? 1 : 0;
       obj->name = "T<>";
 
       return &obj->base;
@@ -385,6 +347,9 @@ vpiHandle vpip_make_vthr_vector(unsigned base, unsigned wid)
 
 /*
  * $Log: vpi_vthr_vector.cc,v $
+ * Revision 1.6  2002/04/14 02:56:19  steve
+ *  Support signed expressions through to VPI.
+ *
  * Revision 1.5  2002/01/10 01:54:04  steve
  *  odd width thread vectors as strings.
  *