diff --git a/vvp/logic.cc b/vvp/logic.cc
index c42673b4b..617f11215 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 1.24 2005/06/02 16:02:11 steve Exp $"
+#ident "$Id: logic.cc,v 1.25 2005/06/12 00:44:49 steve Exp $"
 #endif
 
 # include  "logic.h"
@@ -260,12 +260,6 @@ void compile_functor(char*label, char*type,
       } else if (strcmp(type, "BUFZ") == 0) {
 	    obj = new vvp_fun_bufz();
 #if 0
-      } else if (strcmp(type, "PMOS") == 0) {
-	    obj = new vvp_pmos_s;
-
-      } else if (strcmp(type, "NMOS") == 0) {
-	    obj= new vvp_nmos_s;
-
       } else if (strcmp(type, "RPMOS") == 0) {
 	    obj = new vvp_rpmos_s;
 
@@ -278,6 +272,12 @@ void compile_functor(char*label, char*type,
       } else if (strcmp(type, "MUXZ") == 0) {
 	    obj = new vvp_fun_muxz();
 
+      } else if (strcmp(type, "NMOS") == 0) {
+	    obj = new vvp_fun_pmos(true);
+
+      } else if (strcmp(type, "PMOS") == 0) {
+	    obj = new vvp_fun_pmos(false);
+
       } else if (strcmp(type, "EEQ") == 0) {
 	    obj = new table_functor_s(ft_EEQ);
 
@@ -346,6 +346,9 @@ void compile_functor(char*label, char*type,
 
 /*
  * $Log: logic.cc,v $
+ * Revision 1.25  2005/06/12 00:44:49  steve
+ *  Implement nmos and pmos devices.
+ *
  * Revision 1.24  2005/06/02 16:02:11  steve
  *  Add support for notif0/1 gates.
  *  Make delay nodes support inertial delay.
diff --git a/vvp/npmos.cc b/vvp/npmos.cc
index 2b170d9fe..3169098e9 100644
--- a/vvp/npmos.cc
+++ b/vvp/npmos.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2005 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
@@ -17,119 +17,85 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: npmos.cc,v 1.10 2005/04/28 04:59:53 steve Exp $"
+#ident "$Id: npmos.cc,v 1.11 2005/06/12 00:44:49 steve Exp $"
 #endif
 
 # include  "npmos.h"
-# include  "schedule.h"
 
-void vvp_pmos_s::set(vvp_ipoint_t ptr, bool push, unsigned v, unsigned s)
+vvp_fun_pmos::vvp_fun_pmos(bool enable_invert)
 {
-#if 0
-      put(ptr, v);
+      inv_en_ = enable_invert;
+}
 
-      unsigned pp = ipoint_port(ptr);
-      if (pp == 0) {
-
-	    /* from IEEE 1384-1995 Table 7-8 */
-	    static const unsigned char rmos_table[8]
-		  = { 0, 1, 1, 2, 2, 3, 5, 5 };
-	    /* just reduce SUPPLY to STRONG */
-	    static const unsigned char mos_table[8]
-		  = { 0, 1, 2, 3, 4, 5, 6, 6 };
-
-	    const unsigned char *table = res ? rmos_table : mos_table;
-
-	    unsigned vals = s & 0x88;
-	    unsigned s1 = table[s & 0x7];
-	    unsigned s2 = table[(s & 0x70) >> 4];
-
-	    istr =  vals | s1 | (s2 << 4);
+void vvp_fun_pmos::recv_vec4(vvp_net_ptr_t ptr, vvp_vector4_t bit)
+{
+	/* Data input is processed throught eh recv_vec8 method,
+	   because the strength most be preserved. */
+      if (ptr.port() == 0) {
+	    vvp_vector8_t tmp = bit;
+	    recv_vec8(ptr, tmp);
+	    return;
       }
 
-      unsigned in0 = ival & 0x03;
-      unsigned in1 = (ival >> 2) & 0x03;
+      if (ptr.port() != 1)
+	    return;
 
-      unsigned char outH = 0x88 | ((istr & 7)<<4) | (0);
-      unsigned char outL = 0x00 | ((istr & 7)<<0) | (0);
-      unsigned char outX = 0x80 | (istr & 7) | (istr & 0x70);
+      en_ = inv_en_? ~bit : bit;
+      generate_output_(ptr);
+}
 
-      in1 ^= pol;
+void vvp_fun_pmos::recv_vec8(vvp_net_ptr_t ptr, vvp_vector8_t bit)
+{
+      if (ptr.port() == 1) {
+	    recv_vec4(ptr, reduce4(bit));
+	    return;
+      }
 
-      unsigned char val;
-      unsigned char str;
+      if (ptr.port() != 0)
+	    return;
 
-      if (in1 == 0) {
-	    // gate on; output follows input
-	    val = in0;
-	    str = istr;
-      } else if (in0 == 3) {
-	    val = 3;
-	    str = HiZ;
-      } else if (in1 == 2 || in1 == 3) {
-	    // gate X or Z; output is undefined
-	    val = 2;
-	    switch (in0) {
-		case 0:
-		  str = outL;
+      bit_ = bit;
+      generate_output_(ptr);
+}
+
+void vvp_fun_pmos::generate_output_(vvp_net_ptr_t ptr)
+{
+      vvp_vector8_t out (bit_.size());
+
+      for (unsigned idx = 0 ;  idx < out.size() ;  idx += 1) {
+	    vvp_bit4_t   b_en  = en_.value(idx);
+	    vvp_scalar_t b_bit = bit_.value(idx);
+
+	    switch (b_en) {
+		case BIT4_0:
+		  out.set_bit(idx, b_bit);
 		  break;
-		case 1:
-		  str = outH;
+		case BIT4_1:
+		  out.set_bit(idx, vvp_scalar_t(BIT4_Z,0,0));
 		  break;
 		default:
-		  str = outX;
+		  switch (b_bit.value()) {
+		      case BIT4_0:
+			b_bit = vvp_scalar_t(BIT4_X,b_bit.strength0(),0);
+			break;
+		      case BIT4_1:
+			b_bit = vvp_scalar_t(BIT4_X,0,b_bit.strength1());
+			break;
+		      default:
+			break;
+		  }
+		  out.set_bit(idx, b_bit);
 		  break;
 	    }
-      } else {
-	    // gate off; output is high impedance
-	    val = 3;
-	    str = HiZ;
       }
 
-      put_ostr(val, str, push);
-#else
-      assert(0); // not implemented.
-#endif
+      vvp_send_vec8(ptr.ptr()->out, out);
 }
 
 /*
  * $Log: npmos.cc,v $
- * Revision 1.10  2005/04/28 04:59:53  steve
- *  Remove dead functor code.
- *
- * Revision 1.9  2004/10/04 01:10:59  steve
- *  Clean up spurious trailing white space.
- *
- * Revision 1.8  2002/08/12 01:35:08  steve
- *  conditional ident string using autoconfig.
- *
- * Revision 1.7  2001/12/06 03:31:24  steve
- *  Support functor delays for gates and UDP devices.
- *  (Stephan Boettcher)
- *
- * Revision 1.6  2001/11/07 03:34:42  steve
- *  Use functor pointers where vvp_ipoint_t is unneeded.
- *
- * Revision 1.5  2001/10/31 04:27:47  steve
- *  Rewrite the functor type to have fewer functor modes,
- *  and use objects to manage the different types.
- *  (Stephan Boettcher)
- *
- * Revision 1.4  2001/10/24 03:18:52  steve
- *  npmos outputs have 3bit strengths, not 2.
- *
- * Revision 1.3  2001/10/18 17:30:26  steve
- *  Support rnpmos devices. (Philip Blundell)
- *
- * Revision 1.2  2001/10/11 18:20:51  steve
- *  npmos devices pass strength.
- *
- * Revision 1.1  2001/10/09 02:28:17  steve
- *  Add the PMOS and NMOS functor types.
- *
- * Revision 1.1  2001/05/31 04:12:43  steve
- *  Make the bufif0 and bufif1 gates strength aware,
- *  and accurately propagate strengths of outputs.
+ * Revision 1.11  2005/06/12 00:44:49  steve
+ *  Implement nmos and pmos devices.
  *
  */
 
diff --git a/vvp/npmos.h b/vvp/npmos.h
index 546cbb017..57c3894dc 100644
--- a/vvp/npmos.h
+++ b/vvp/npmos.h
@@ -1,7 +1,7 @@
 #ifndef __npmos_H
 #define __npmos_H
 /*
- * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2005 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
@@ -19,62 +19,53 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: npmos.h,v 1.5 2004/10/04 01:10:59 steve Exp $"
+#ident "$Id: npmos.h,v 1.6 2005/06/12 00:44:49 steve Exp $"
 #endif
 
-# include  "functor.h"
+# include  "vvp_net.h"
 
-class vvp_pmos_s  : public functor_s {
+/*
+ * The vvp_fun_pmos functor is similar to the vvp_fun_bufif. The
+ * principle difference is that it has no drive of its own, instead
+ * taking drive strength from its data input. In other words, it is
+ * not a buffer but a uni-directional switch.
+ *
+ * The truth table for the PMOS device is:
+ *
+ *     Q = D C  (D is port0, C is port1)
+ *     -------
+ *     0 | 0 0
+ *     Z | 0 1
+ *     L | 0 x
+ *     1 | 1 0
+ *     Z | 1 1
+ *     H | 1 x
+ *
+ * This class also implements the NMOS device, which is the same as
+ * the PMOS device, but the Control input inverted. The enable_invert
+ * flag to the costructor activates this invertion.
+ */
+
+class vvp_fun_pmos  : public vvp_net_fun_t {
 
     public:
-      vvp_pmos_s() : istr(StX), pol(0), res(0) {}
-      virtual void set(vvp_ipoint_t i, bool push, unsigned val, unsigned str);
+      explicit vvp_fun_pmos(bool enable_invert);
 
-    protected:
-      unsigned char istr;
-      unsigned pol : 1;
-      unsigned res : 1;
-};
+      void recv_vec4(vvp_net_ptr_t port, vvp_vector4_t bit);
+      void recv_vec8(vvp_net_ptr_t port, vvp_vector8_t bit);
 
-class vvp_nmos_s  : public vvp_pmos_s {
+    private:
+      void generate_output_(vvp_net_ptr_t port);
 
-    public:
-      vvp_nmos_s() { pol = 1; res = 0; }
-};
-
-class vvp_rpmos_s  : public vvp_pmos_s {
-
-    public:
-      vvp_rpmos_s() { pol = 0; res = 1; }
-};
-
-class vvp_rnmos_s  : public vvp_pmos_s {
-
-    public:
-      vvp_rnmos_s() { pol = 1; res = 1; }
+      vvp_vector8_t bit_;
+      vvp_vector4_t en_;
+      bool inv_en_;
 };
 
 /*
  * $Log: npmos.h,v $
- * Revision 1.5  2004/10/04 01:10:59  steve
- *  Clean up spurious trailing white space.
- *
- * Revision 1.4  2002/08/12 01:35:08  steve
- *  conditional ident string using autoconfig.
- *
- * Revision 1.3  2001/10/31 04:27:47  steve
- *  Rewrite the functor type to have fewer functor modes,
- *  and use objects to manage the different types.
- *  (Stephan Boettcher)
- *
- * Revision 1.2  2001/10/18 17:30:26  steve
- *  Support rnpmos devices. (Philip Blundell)
- * Revision 1.1 2001/10/09 02:28:17 steve Add the
- * PMOS and NMOS functor types.
- *
- * Revision 1.1  2001/05/31 04:12:43  steve
- *  Make the bufif0 and bufif1 gates strength aware,
- *  and accurately propagate strengths of outputs.
+ * Revision 1.6  2005/06/12 00:44:49  steve
+ *  Implement nmos and pmos devices.
  *
  */
 #endif
diff --git a/vvp/vvp_net.h b/vvp/vvp_net.h
index 54d3f0e3b..eccb68637 100644
--- a/vvp/vvp_net.h
+++ b/vvp/vvp_net.h
@@ -18,7 +18,7 @@
  *    along with this program; if not, write to the Free Software
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
-#ident "$Id: vvp_net.h,v 1.29 2005/06/02 16:02:11 steve Exp $"
+#ident "$Id: vvp_net.h,v 1.30 2005/06/12 00:44:49 steve Exp $"
 
 # include  "config.h"
 # include  <assert.h>
@@ -211,14 +211,16 @@ extern ostream& operator<< (ostream&, vvp_scalar_t);
  *
  * a vvp_vector8_t object can be created from a vvp_vector4_t and a
  * strength value. The vvp_vector8_t bits have the values of the input
- * vector, all with the strength specified.
+ * vector, all with the strength specified. If no strength is
+ * specified, then the conversion from bit4 to a scalar will use the
+ * Verilog convention default of strong (6).
  */
 class vvp_vector8_t {
 
     public:
       explicit vvp_vector8_t(unsigned size =0);
 	// Make a vvp_vector8_t from a vector4 and a specified strength.
-      explicit vvp_vector8_t(const vvp_vector4_t&that, unsigned str);
+      vvp_vector8_t(const vvp_vector4_t&that, unsigned str =6);
       explicit vvp_vector8_t(const vvp_vector4_t&that,
 			     unsigned str0,
 			     unsigned str1);
@@ -744,6 +746,9 @@ class vvp_wide_fun_t : public vvp_net_fun_t {
 
 /*
  * $Log: vvp_net.h,v $
+ * Revision 1.30  2005/06/12 00:44:49  steve
+ *  Implement nmos and pmos devices.
+ *
  * Revision 1.29  2005/06/02 16:02:11  steve
  *  Add support for notif0/1 gates.
  *  Make delay nodes support inertial delay.