diff --git a/vvp/codes.h b/vvp/codes.h
index 87e9612b5..74e88bf2a 100644
--- a/vvp/codes.h
+++ b/vvp/codes.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: codes.h,v 1.56 2003/01/26 18:16:22 steve Exp $"
+#ident "$Id: codes.h,v 1.57 2003/02/06 17:41:47 steve Exp $"
 #endif
 
 
@@ -104,6 +104,7 @@ extern bool of_SET_X0(vthread_t thr, vvp_code_t code);
 extern bool of_SHIFTL_I0(vthread_t thr, vvp_code_t code);
 extern bool of_SHIFTR_I0(vthread_t thr, vvp_code_t code);
 extern bool of_SUB(vthread_t thr, vvp_code_t code);
+extern bool of_SUB_WR(vthread_t thr, vvp_code_t code);
 extern bool of_SUBI(vthread_t thr, vvp_code_t code);
 extern bool of_VPI_CALL(vthread_t thr, vvp_code_t code);
 extern bool of_WAIT(vthread_t thr, vvp_code_t code);
@@ -168,6 +169,9 @@ extern vvp_code_t codespace_index(vvp_cpoint_t ptr);
 
 /*
  * $Log: codes.h,v $
+ * Revision 1.57  2003/02/06 17:41:47  steve
+ *  Add the %sub/wr instruction.
+ *
  * Revision 1.56  2003/01/26 18:16:22  steve
  *  Add %cvt/ir and %cvt/ri instructions, and support
  *  real values passed as arguments to VPI tasks.
diff --git a/vvp/compile.cc b/vvp/compile.cc
index a8d3e6c36..054c87502 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 1.152 2003/02/03 01:09:20 steve Exp $"
+#ident "$Id: compile.cc,v 1.153 2003/02/06 17:41:47 steve Exp $"
 #endif
 
 # include  "arith.h"
@@ -149,6 +149,7 @@ const static struct opcode_table_s opcode_table[] = {
       { "%shiftl/i0", of_SHIFTL_I0, 2, {OA_BIT1,OA_NUMBER,   OA_NONE} },
       { "%shiftr/i0", of_SHIFTR_I0, 2, {OA_BIT1,OA_NUMBER,   OA_NONE} },
       { "%sub",    of_SUB,    3,  {OA_BIT1,     OA_BIT2,     OA_NUMBER} },
+      { "%sub/wr", of_SUB_WR, 2,  {OA_BIT1,     OA_BIT2,     OA_NONE} },
       { "%subi",   of_SUBI,   3,  {OA_BIT1,     OA_BIT2,     OA_NUMBER} },
       { "%wait",   of_WAIT,   1,  {OA_FUNC_PTR, OA_NONE,     OA_NONE} },
       { "%xnor",   of_XNOR,   3,  {OA_BIT1,     OA_BIT2,     OA_NUMBER} },
@@ -1519,6 +1520,9 @@ void compile_net(char*label, char*name, int msb, int lsb, bool signed_flag,
 
 /*
  * $Log: compile.cc,v $
+ * Revision 1.153  2003/02/06 17:41:47  steve
+ *  Add the %sub/wr instruction.
+ *
  * Revision 1.152  2003/02/03 01:09:20  steve
  *  Allow $display of $simtime.
  *
diff --git a/vvp/opcodes.txt b/vvp/opcodes.txt
index 3cb85d8d9..0ea1b1481 100644
--- a/vvp/opcodes.txt
+++ b/vvp/opcodes.txt
@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2001-2003 Stephen Williams (steve@icarus.com)
  *
- *  $Id: opcodes.txt,v 1.47 2003/01/26 18:16:22 steve Exp $
+ *  $Id: opcodes.txt,v 1.48 2003/02/06 17:41:47 steve Exp $
  */
 
 
@@ -33,6 +33,12 @@ See also the %sub instruction.
 
 * %add/wr <bit-l>, <bit-r>
 
+This is the real valued version of hte %add instruction. The arguments
+are word indices of the operands. The right operand is added into the
+left operand.
+
+See also the %sub/wr instruction.
+
 
 * %addi <bit-l>, <imm>, <wid>
 
@@ -548,6 +554,14 @@ the <wid> of the left vector. The result replaces the left vector.
 
 See also the %addi instruction.
 
+
+* %sub/wr <bit-l>, <bit-r>
+
+This instruction operates on real values in word registers. The right
+indexed value is subtracted from the left indexed value, and the
+result placed in the left index.
+
+
 * %vpi_call <name> [, ...]
 
 This instruction makes a call to a system task that was declared using
@@ -598,7 +612,7 @@ and leaves the result in the <dst> vector. xor is this:
 
 
 /*
- * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2001-2003 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
diff --git a/vvp/vthread.cc b/vvp/vthread.cc
index 0dd931cba..6987e9755 100644
--- a/vvp/vthread.cc
+++ b/vvp/vthread.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: vthread.cc,v 1.99 2003/01/27 00:14:37 steve Exp $"
+#ident "$Id: vthread.cc,v 1.100 2003/02/06 17:41:47 steve Exp $"
 #endif
 
 # include  "vthread.h"
@@ -2417,6 +2417,14 @@ bool of_SUB(vthread_t thr, vvp_code_t cp)
       return true;
 }
 
+bool of_SUB_WR(vthread_t thr, vvp_code_t cp)
+{
+      double l = thr->words[cp->bit_idx[0]].w_real;
+      double r = thr->words[cp->bit_idx[1]].w_real;
+      thr->words[cp->bit_idx[0]].w_real = l - r;
+      return true;
+}
+
 bool of_SUBI(vthread_t thr, vvp_code_t cp)
 {
       assert(cp->bit_idx[0] >= 4);
@@ -2608,6 +2616,9 @@ bool of_CALL_UFUNC(vthread_t thr, vvp_code_t cp)
 
 /*
  * $Log: vthread.cc,v $
+ * Revision 1.100  2003/02/06 17:41:47  steve
+ *  Add the %sub/wr instruction.
+ *
  * Revision 1.99  2003/01/27 00:14:37  steve
  *  Support in various contexts the $realtime
  *  system task.