diff --git a/C/load_foreign.c b/C/load_foreign.c
index 7edbe673f..1df99f81f 100644
--- a/C/load_foreign.c
+++ b/C/load_foreign.c
@@ -29,8 +29,8 @@ static char     SccsId[] = "%W% %G%.2";
 #include "Foreign.h"
 
 #if _WIN32 || defined(__CYGWIN__)
-#ifndef YAP_SHLIB_SUFFIX
-#define YAP_SHLIB_SUFFIX ".dll"
+#ifndef SO_EXT
+#define SO_EXT ".dll"
 #endif
 #endif
 
@@ -210,12 +210,12 @@ p_call_shared_object_function( USES_REGS1 ) {
 
 static Int
 p_obj_suffix( USES_REGS1 ) {
-  return Yap_unify(Yap_StringToList(YAP_SHLIB_SUFFIX),ARG1);
+  return Yap_unify(Yap_StringToList(SO_EXT),ARG1);
 }
 
 static Int
 p_open_shared_objects( USES_REGS1 ) {
-#ifdef YAP_SHLIB_SUFFIX
+#ifdef SO_EXT
   return TRUE;
 #else
   return FALSE;
diff --git a/C/pl-yap.c b/C/pl-yap.c
index a83ab13d2..ab8cddfb5 100755
--- a/C/pl-yap.c
+++ b/C/pl-yap.c
@@ -319,7 +319,8 @@ word lookupAtom(const char *s, size_t len)
 
   /* dirty trick to ensure s is null terminated */
   char *st = (char *)s;
-  st[len] = '\0';
+  if (st[len])
+    st[len] = '\0';
   if (len >= strlen(s)) {
     at = YAP_LookupAtom(st);
   } else {
@@ -1300,12 +1301,6 @@ sysError(const char *fm, ...)
 
 #if THREADS
 
-#define COUNT_MUTEX_INITIALIZER(name) \
- { PTHREAD_MUTEX_INITIALIZER, \
-   name, \
-   0L \
- }
-
 static int
 recursive_attr(pthread_mutexattr_t **ap)
 { static int done;
@@ -1360,27 +1355,4 @@ recursiveMutexInit(recursiveMutex *m)
 
 }
 
-counting_mutex _PL_mutexes[] =
-{ COUNT_MUTEX_INITIALIZER("L_MISC"),
-  COUNT_MUTEX_INITIALIZER("L_ALLOC"),
-  COUNT_MUTEX_INITIALIZER("L_ATOM"),
-  COUNT_MUTEX_INITIALIZER("L_FLAG"),
-  COUNT_MUTEX_INITIALIZER("L_FUNCTOR"),
-  COUNT_MUTEX_INITIALIZER("L_RECORD"),
-  COUNT_MUTEX_INITIALIZER("L_THREAD"),
-  COUNT_MUTEX_INITIALIZER("L_PREDICATE"),
-  COUNT_MUTEX_INITIALIZER("L_MODULE"),
-  COUNT_MUTEX_INITIALIZER("L_TABLE"),
-  COUNT_MUTEX_INITIALIZER("L_BREAK"),
-  COUNT_MUTEX_INITIALIZER("L_FILE"),
-  COUNT_MUTEX_INITIALIZER("L_PLFLAG"),
-  COUNT_MUTEX_INITIALIZER("L_OP"),
-  COUNT_MUTEX_INITIALIZER("L_INIT"),
-  COUNT_MUTEX_INITIALIZER("L_TERM"),
-  COUNT_MUTEX_INITIALIZER("L_GC"),
-  COUNT_MUTEX_INITIALIZER("L_AGC"),
-  COUNT_MUTEX_INITIALIZER("L_FOREIGN"),
-  COUNT_MUTEX_INITIALIZER("L_OS")
-};
-
 #endif
diff --git a/C/yap-args.c b/C/yap-args.c
index f6187ffb1..73c94343c 100755
--- a/C/yap-args.c
+++ b/C/yap-args.c
@@ -131,10 +131,10 @@ add_end_dot(char arg[])
 static int
 dump_runtime_variables(void)
 {
-  fprintf(stdout,"CC=\"%s\"\n",YAP_CC);
+  fprintf(stdout,"CC=\"%s\"\n",C_CC);
   fprintf(stdout,"YAP_ROOTDIR=\"%s\"\n",YAP_ROOTDIR);
-  fprintf(stdout,"YAP_LIBS=\"%s\"\n",YAP_LIBS);
-  fprintf(stdout,"YAP_SHLIB_SUFFIX=\"%s\"\n",YAP_SHLIB_SUFFIX);
+  fprintf(stdout,"YAP_LIBS=\"%s\"\n",C_LIBS);
+  fprintf(stdout,"YAP_SHLIB_SUFFIX=\"%s\"\n",SO_EXT);
   fprintf(stdout,"YAP_VERSION=%d\n",YAP_VERSION);
   exit(0);
   return 1;
diff --git a/H/eval.h b/H/eval.h
index 54ca42910..a11d585b9 100644
--- a/H/eval.h
+++ b/H/eval.h
@@ -188,6 +188,7 @@ Yap_Eval(Term t)
   return Yap_InnerEval(t);
 }
 
+#ifdef P
 inline static Term
 Yap_FoundArithError(Term t, Term inp)
 { 
@@ -199,6 +200,7 @@ Yap_FoundArithError(Term t, Term inp)
   }
   return t;
 }
+#endif
 
 
 #define RINT(v)       return(MkIntegerTerm(v))
diff --git a/Makefile.in b/Makefile.in
index fa9031c50..84328c0b6 100755
--- a/Makefile.in
+++ b/Makefile.in
@@ -74,6 +74,7 @@ AWK=@AWK@
 CPP=@CPP@
 DEFS=@DEFS@ -D_YAP_NOT_INSTALLED_=1
 LIBS=@LIBS@
+DLL_LIBS=@LIBS@ @EXTRA_LIBS_FOR_DLLS@
 LDFLAGS=@LDFLAGS@
 LN_S=@LN_S@
 M4=@M4@
@@ -276,8 +277,8 @@ C_SOURCES= \
 	$(srcdir)/OPTYap/or.thread_engine.c \
 	$(srcdir)/OPTYap/or.scheduler.c $(srcdir)/OPTYap/or.cut.c \
 	$(srcdir)/OPTYap/tab.tries.c $(srcdir)/OPTYap/tab.completion.c \
-	$(srcdir)/library/mpi/mpi.c $(srcdir)/library/mpi/mpe.c \
-	$(srcdir)/library/lammpi/yap_mpi.c $(srcdir)/library/lammpi/hash.c $(srcdir)/library/lammpi/prologterms2c.c  \
+	# $(srcdir)/library/mpi/mpi.c $(srcdir)/library/mpi/mpe.c \
+	# $(srcdir)/library/lammpi/yap_mpi.c $(srcdir)/library/lammpi/hash.c $(srcdir)/library/lammpi/prologterms2c.c  \
 	$(srcdir)/C/cut_c.c \
 	$(srcdir)/library/dialect/swi/fli/swi.c \
 	$(srcdir)/library/dialect/swi/fli/blobs.c \
@@ -373,7 +374,7 @@ ENGINE_OBJECTS = \
 	udi.o\
 	unify.o userpreds.o utilpreds.o \
 	yap-args.o write.o \
-	blobs.o swi.o ypstdio.o $(IOLIB_OBJECTS)  @MPI_OBJS@
+	blobs.o swi.o ypstdio.o $(IOLIB_OBJECTS)
 
 LIBTAI_OBJECTS = \
 	tai_add.o tai_now.o tai_pack.o \
@@ -431,12 +432,13 @@ parms.h:	Makefile
 		@echo $(VERSION) | $(AWK) -F. '{ printf("#define YAP_VERSION %d\n", $$1 * 10000 + $$2 * 100 + $$3); }' >> $@%
 		@echo "#define MYDDAS_VERSION	    \"$(MYDDAS_VERSION)\""       >> $@%
 		@echo "#define YAP_ARCH	    \"$(ARCH)\""       >> $@%
-		@echo "#define YAP_LIBS	    \"$(LIBS)\""     >> $@%
+		@echo "#define C_LIBS	    \"$(LIBS)\""     >> $@%
+		@echo "#define C_LIBPLSO	    \"$(DLL_LIBS)\""     >> $@%
 		@echo "#define YAP_YAPLIB	    \"$(YAPLIB)\""   >> $@%
-		@echo "#define YAP_CC	    \"$(CC)\""	       >> $@%
-		@echo "#define YAP_CFLAGS	    \"$(CFLAGS)\"" >> $@%
-		@echo "#define YAP_LDFLAGS    \"$(LDFLAGS)\""    >> $@%
-		@echo "#define YAP_SHLIB_SUFFIX    \".\" \"$(SO)\""    >> $@%
+		@echo "#define C_CC	    \"$(CC)\""	       >> $@%
+		@echo "#define C_CFLAGS	    \"$(CFLAGS)\"" >> $@%
+		@echo "#define C_LDFLAGS    \"$(LDFLAGS)\""    >> $@%
+		@echo "#define SO_EXT    \".\" \"$(SO)\""    >> $@%
 		@echo "#define YAP_TIMESTAMP \"`date +%s`\"" >> $@%
 		@echo "#define YAP_SVERSION   \"YAP $(VERSION) ($(ARCH)): `date`\"" >> $@%
 		@if cmp -s $@% $@; then rm $@%; else mv $@% $@; fi
@@ -696,7 +698,7 @@ mycb: $(srcdir)/mycb.c
 
 all: startup.yss
 	@ENABLE_GECODE@ @INSTALL_DLLS@ (cd library/gecode; $(MAKE))
-	@INSTALL_DLLS@ (cd library/lammpi; $(MAKE))
+	@INSTALL_MPI@ (cd library/lammpi; $(MAKE))
 	@INSTALL_MATLAB@ (cd library/matlab; $(MAKE))
 	@INSTALL_DLLS@ (cd library/matrix; $(MAKE))
 	@INSTALL_DLLS@ (cd library/random; $(MAKE))
@@ -737,7 +739,7 @@ startup.yss: yap@EXEC_SUFFIX@ $(PL_SOURCES)
 	echo "bootstrap('$(srcdir)/pl/init.yap'). module(user). qsave_program('startup.yss')." |  @PRE_INSTALL_ENV@ ./yap -b $(srcdir)/pl/boot.yap
 
 yap@EXEC_SUFFIX@: $(HEADERS) yap.o @YAPLIB@
-	$(MPI_CC) $(EXECUTABLE_CFLAGS) $(LDFLAGS) -o yap yap.o @YAPLIB@ $(LIBS) @MPI_LIBS@
+	$(MPI_CC) $(EXECUTABLE_CFLAGS) $(LDFLAGS) -o yap yap.o @YAPLIB@ $(LIBS)
 
 yap-win: yap-win@EXEC_SUFFIX@
 
@@ -745,7 +747,7 @@ yapwin: yap-win@EXEC_SUFFIX@
 
 yap-win@EXEC_SUFFIX@: $(PLCONS_OBJECTS) $(HEADERS) @YAPLIB@
 	(cd swi/console; $(MAKE))
-	$(MPI_CC) -municode -DUNICODE -D_UNICODE $(EXECUTABLE_CFLAGS) $(LDFLAGS) -Wl,-subsystem,windows -o yap-win $(PLCONS_OBJECTS) plterm.dll @YAPLIB@ $(LIBS) @MPI_LIBS@
+	$(MPI_CC) -municode -DUNICODE -D_UNICODE $(EXECUTABLE_CFLAGS) $(LDFLAGS) -Wl,-subsystem,windows -o yap-win $(PLCONS_OBJECTS) plterm.dll @YAPLIB@ $(LIBS) @MPILDF@
 
 libYap.a: $(LIB_OBJECTS) 
 	-rm -f libYap.a
@@ -772,7 +774,7 @@ install_unix: startup.yss libYap.a
 	$(INSTALL) $(srcdir)/README $(DESTDIR)$(DOCSDIR)
 	$(INSTALL) $(srcdir)/COPYING $(DESTDIR)$(DOCSDIR)
 	for f in $(PL_SOURCES); do $(INSTALL) $$f $(DESTDIR)$(SHAREDIR)/Yap/pl; done
-	@INSTALL_DLLS@ (cd library/lammpi; $(MAKE) install)
+	@INSTALL_MPI@ (cd library/lammpi; $(MAKE) install)
 	@INSTALL_DLLS@ (cd library/matrix; $(MAKE) install)
 	@INSTALL_DLLS@ (cd library/random; $(MAKE) install)
 	@INSTALL_DLLS@ (cd library/regex; $(MAKE) install)
@@ -915,7 +917,7 @@ depend: $(HEADERS) $(C_SOURCES)
 clean: clean_docs
 	rm -f *.o *~ *.BAK *.a
 	@ENABLE_GECODE@ @INSTALL_DLLS@ (cd library/gecode; $(MAKE) clean)
-	@INSTALL_DLLS@ (cd library/lammpi; $(MAKE) clean)
+	@INSTALL_MPI@ (cd library/lammpi; $(MAKE) clean)
 	@INSTALL_MATLAB@ (cd library/matlab; $(MAKE) clean)
 	@INSTALL_DLLS@ (cd library/matrix; $(MAKE) clean)
 	@INSTALL_DLLS@ (cd library/random; $(MAKE) clean)
diff --git a/config.h.in b/config.h.in
index bf99ba75c..e89340c7d 100755
--- a/config.h.in
+++ b/config.h.in
@@ -198,6 +198,7 @@
 #undef  HAVE_GETHOSTNAME
 #undef  HAVE_GETHRTIME
 #undef  HAVE_GETPAGESIZE
+#undef  HAVE_GETPID
 #undef  HAVE_GETPWNAM
 #undef  HAVE_GETRUSAGE
 #undef  HAVE_GETTIMEOFDAY
diff --git a/configure b/configure
index 4323e75bd..5bdf00987 100755
--- a/configure
+++ b/configure
@@ -671,15 +671,14 @@ EXTRA_INCLUDES_FOR_WIN32
 ENABLE_WINCONSOLE
 STATIC_MODE
 MAX_WORKERS
-LAMOBJS
 JAVALIBS
 JPLLIBS
 JPLCFLAGS
 INSTALLCLP
 INSTALL_COMMAND
-MPI_LIBS
-MPI_OBJS
-LAM_MPI_CC
+MPICF
+MPILDF
+INSTALL_MPI
 YAPMPILIB
 IN_UNIX
 LIBJPL
@@ -735,13 +734,13 @@ CPLINT_SHLIB_LD
 CPLINT_LDFLAGS
 CPLINT_CFLAGS
 CPLINT_LIBS
+MPI_CC
 ENABLE_PRISM
 ENABLE_GECODE
 NVCC
 PYTHON
 REXE
 INSTALL_INFO
-MPI_CC
 AR
 RANLIB
 INSTALL_DATA
@@ -867,7 +866,6 @@ with_readline
 with_matlab
 with_mpi
 with_mpe
-with_lam
 with_heap_space
 with_stack_space
 with_trail_space
@@ -1548,7 +1546,6 @@ Optional Packages:
  --with-matlab=DIR      use MATLAB package in DIR
  --with-mpi=DIR           use LAM/MPI library in DIR
  --with-mpe=DIR           use MPE library in DIR
- --with-lam=DIR           use LAM MPI library in DIR
  --with-heap-space=space  default heap size in Kbytes
  --with-stack-space=space default stack size in Kbytes
  --with-trail-space=space default trail size in Kbytes
@@ -4884,16 +4881,16 @@ fi
 # Check whether --with-mpi was given.
 if test "${with_mpi+set}" = set; then :
   withval=$with_mpi; if test "$withval" = yes; then
-        		yap_cv_lam=yes
+        		yap_cv_mpi=yes
 	elif test "$withval" = no; then
-		yap_cv_lam=no
+		yap_cv_mpi=no
 	else
-		yap_cv_lam=$with_mpi
+		yap_cv_mpi=$with_mpi
 		LDFLAGS="$LDFLAGS -L${yap_cv_mpi}/lib"
 		CPPFLAGS="$CPPFLAGS -I${yap_cv_mpi}/include"
 	fi
 else
-  yap_cv_lam=no
+  yap_cv_mpi=no
 fi
 
 
@@ -4916,23 +4913,6 @@ fi
 
 
 
-# Check whether --with-lam was given.
-if test "${with_lam+set}" = set; then :
-  withval=$with_lam; if test "$withval" = yes; then
-	        yap_cv_lam=yes
-	elif test "$withval" = no; then
-		yap_cv_lam=no
-	else
-		yap_cv_lam=$with_lam
-		LDFLAGS="$LDFLAGS -L${yap_cv_lam}/lib"
-		CPPFLAGS="$CPPFLAGS -I${yap_cv_lam}/include"
-	fi
-else
-  yap_cv_lam=no
-fi
-
-
-
 # Check whether --with-heap-space was given.
 if test "${with_heap_space+set}" = set; then :
   withval=$with_heap_space; if test "$withval" = yes; then
@@ -5201,7 +5181,9 @@ then
        C_PARSER_FLAGS="-O3 -Wall -Wstrict-prototypes -Wmissing-prototypes $CFLAGS"
        CFLAGS="-O3 -fomit-frame-pointer -Wall -Wstrict-prototypes -Wmissing-prototypes $CFLAGS"
        case "`$CC --version < /dev/null`" in
-	  *3.4*) CFLAGS="-fno-gcse -fno-crossjumping $CFLAGS" ;;
+	  *3.4*)
+	    CFLAGS="-fno-gcse -fno-crossjumping $CFLAGS"
+	  ;;
        esac
        case "$target_cpu" in
         i*86*)
@@ -5567,98 +5549,6 @@ else
   AR="$ac_cv_prog_AR"
 fi
 
-if test -n "$ac_tool_prefix"; then
-  # Extract the first word of "${ac_tool_prefix}mpicc", so it can be a program name with args.
-set dummy ${ac_tool_prefix}mpicc; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_MPI_CC+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test -n "$MPI_CC"; then
-  ac_cv_prog_MPI_CC="$MPI_CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
-    ac_cv_prog_MPI_CC="${ac_tool_prefix}mpicc"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-MPI_CC=$ac_cv_prog_MPI_CC
-if test -n "$MPI_CC"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $MPI_CC" >&5
-$as_echo "$MPI_CC" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-
-fi
-if test -z "$ac_cv_prog_MPI_CC"; then
-  ac_ct_MPI_CC=$MPI_CC
-  # Extract the first word of "mpicc", so it can be a program name with args.
-set dummy mpicc; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_ac_ct_MPI_CC+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test -n "$ac_ct_MPI_CC"; then
-  ac_cv_prog_ac_ct_MPI_CC="$ac_ct_MPI_CC" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
-    ac_cv_prog_ac_ct_MPI_CC="mpicc"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-ac_ct_MPI_CC=$ac_cv_prog_ac_ct_MPI_CC
-if test -n "$ac_ct_MPI_CC"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_MPI_CC" >&5
-$as_echo "$ac_ct_MPI_CC" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-  if test "x$ac_ct_MPI_CC" = x; then
-    MPI_CC="${CC}"
-  else
-    case $cross_compiling:$ac_tool_warned in
-yes:)
-{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
-$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
-ac_tool_warned=yes ;;
-esac
-    MPI_CC=$ac_ct_MPI_CC
-  fi
-else
-  MPI_CC="$ac_cv_prog_MPI_CC"
-fi
-
 # Extract the first word of "install-info", so it can be a program name with args.
 set dummy install-info; ac_word=$2
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
@@ -8519,6 +8409,12 @@ fi
 	;;
 esac
 
+if test "$CC" = icc
+then
+  MPI_CC="$CC"
+  yap_cv_mpi=no
+fi
+
 if test "$dynamic_loading" = "yes"
 then
   YAPLIB_CFLAGS="$SHLIB_CFLAGS"
@@ -8634,138 +8530,100 @@ if test "$tabling" = "yes"
   YAP_EXTRAS="$YAP_EXTRAS -DTABLING=1"
 fi
 
-LAMOBJS=""
-MPI_OBJS=
-LAM_MPI_CC=${MPI_CC}
-if  test "$yap_cv_lam" != "no" ; then
-  if test "$yap_cv_lam" != "yes" ; then
-    LAM_MPI_CC="$yap_cv_lam"/bin/mpicc
-    MPI_CC="$yap_cv_lam"/bin/mpicc
-    CPPFLAGS="$CPPFLAGS -I ${yap_cv_lam}/include"
-    LDFLAGS="$LDFLAGS -L${yap_cv_lam}/lib"
-  fi
-  OLD_CC=${CC}
-  CC=${LAM_MPI_CC}
-  ac_fn_c_check_header_mongrel "$LINENO" "mpi.h" "ac_cv_header_mpi_h" "$ac_includes_default"
-if test "x$ac_cv_header_mpi_h" = xyes; then :
-  LAMOBJS=yap_mpi."$SO"
-                 $as_echo "#define HAVE_LIBMPI 1" >>confdefs.h
-
+if test "$yap_cv_mpi" != "no"; then
+    if test "$yap_cv_mpi" != "yes"; then
+      # Extract the first word of "mpicc", so it can be a program name with args.
+set dummy mpicc; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_MPI_CC+:} false; then :
+  $as_echo_n "(cached) " >&6
 else
-  LAMOBJS=""
-                 $as_echo "#define HAVE_LIBMPI 0" >>confdefs.h
+  case $MPI_CC in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_MPI_CC="$MPI_CC" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+as_dummy="$PATH:/sbin:/usr/sbin:/usr/etc:/usr/local/sbin"
+for as_dir in $as_dummy
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_MPI_CC="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
 
+  test -z "$ac_cv_path_MPI_CC" && ac_cv_path_MPI_CC="true"
+  ;;
+esac
+fi
+MPI_CC=$ac_cv_path_MPI_CC
+if test -n "$MPI_CC"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $MPI_CC" >&5
+$as_echo "$MPI_CC" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
 fi
 
 
-  CC=${OLD_CC}
-  elif test "$yap_cv_mpi" != "no"; then
+    else
+      # Extract the first word of "mpicc", so it can be a program name with args.
+set dummy mpicc; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_MPI_CC+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  case $MPI_CC in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_MPI_CC="$MPI_CC" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+as_dummy="$yap_cv_mpi/bin:$PATH:/sbin:/usr/sbin:/usr/etc:/usr/local/sbin"
+for as_dir in $as_dummy
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_MPI_CC="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  test -z "$ac_cv_path_MPI_CC" && ac_cv_path_MPI_CC="true"
+  ;;
+esac
+fi
+MPI_CC=$ac_cv_path_MPI_CC
+if test -n "$MPI_CC"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $MPI_CC" >&5
+$as_echo "$MPI_CC" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+    fi
+    MPILDF=`"$MPI_CC" --showme:link`
+    MPICF=`"$MPI_CC" --showme:compile`
+    LIBS="$LIBS $MPILDF"
+    INSTALL_MPI=""
     OLD_CC=${CC}
     CC=${MPI_CC}
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for MPI_Init in -lmpi" >&5
-$as_echo_n "checking for MPI_Init in -lmpi... " >&6; }
-if ${ac_cv_lib_mpi_MPI_Init+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  ac_check_lib_save_LIBS=$LIBS
-LIBS="-lmpi  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char MPI_Init ();
-int
-main ()
-{
-return MPI_Init ();
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_mpi_MPI_Init=yes
-else
-  ac_cv_lib_mpi_MPI_Init=no
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_mpi_MPI_Init" >&5
-$as_echo "$ac_cv_lib_mpi_MPI_Init" >&6; }
-if test "x$ac_cv_lib_mpi_MPI_Init" = xyes; then :
-  LAMOBJS=yap_mpi."$SO"
-                 $as_echo "#define HAVE_LIBMPI 1" >>confdefs.h
-
-else
-  LAMOBJS=yap_mpi."$SO"
-                 $as_echo "#define HAVE_LIBMPI 0" >>confdefs.h
-
-fi
-
-    if test "$ac_cv_lib_mpi_MPI_Init" = yes
-    then
-	#YAPMPILIB=YapMPI.a
-	MPI_OBJS=mpi.o
-    else
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for MPI_Init in -lmpich" >&5
-$as_echo_n "checking for MPI_Init in -lmpich... " >&6; }
-if ${ac_cv_lib_mpich_MPI_Init+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  ac_check_lib_save_LIBS=$LIBS
-LIBS="-lmpich  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char MPI_Init ();
-int
-main ()
-{
-return MPI_Init ();
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_mpich_MPI_Init=yes
-else
-  ac_cv_lib_mpich_MPI_Init=no
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_mpich_MPI_Init" >&5
-$as_echo "$ac_cv_lib_mpich_MPI_Init" >&6; }
-if test "x$ac_cv_lib_mpich_MPI_Init" = xyes; then :
-  $as_echo "#define HAVE_LIBMPICH 1" >>confdefs.h
-
-else
-  $as_echo "#define HAVE_LIBMPICH 0" >>confdefs.h
-
-fi
-
-      if test "$ac_cv_lib_mpich_MPI_Init" = yes
-      then
-	#YAPMPILIB=YapMPI.a
-	MPI_OBJS=mpi.o
-      else
-	#YAPMPILIB=
-	MPI_CC=${CC}
-      fi
-    fi
     for ac_header in mpi.h
 do :
   ac_fn_c_check_header_mongrel "$LINENO" "mpi.h" "ac_cv_header_mpi_h" "$ac_includes_default"
@@ -8779,7 +8637,6 @@ fi
 done
 
     CC=${OLD_CC}
-    MPI_LIBS=
     if test "$yap_cv_mpe" != "no"
     then
      OLD_CC=${CC}
@@ -8848,7 +8705,8 @@ done
      CC=${OLD_CC}
    fi
 else
-    MPI_CC=${CC}
+  INSTALL_MPI="# "
+  MPI_CC=${CC}
 fi
 
 
@@ -10289,7 +10147,7 @@ _ACEOF
 fi
 done
 
-for ac_func in gethrtime getpagesize
+for ac_func in gethrtime getpagesize getpid
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/configure.in b/configure.in
index 8d731a291..5c634a247 100755
--- a/configure.in
+++ b/configure.in
@@ -376,15 +376,15 @@ AC_ARG_WITH(mpi,
 	[ --with-mpi[=DIR]           use LAM/MPI library in DIR],
 	if test "$withval" = yes; then
         dnl handle UBUNTU systems
-		yap_cv_lam=yes
+		yap_cv_mpi=yes
 	elif test "$withval" = no; then
-		yap_cv_lam=no
+		yap_cv_mpi=no
 	else
-		yap_cv_lam=$with_mpi
+		yap_cv_mpi=$with_mpi
 		LDFLAGS="$LDFLAGS -L${yap_cv_mpi}/lib"
 		CPPFLAGS="$CPPFLAGS -I${yap_cv_mpi}/include"
 	fi,
-	[yap_cv_lam=no])
+	[yap_cv_mpi=no])
 
 
 AC_ARG_WITH(mpe,
@@ -400,19 +400,6 @@ AC_ARG_WITH(mpe,
 	fi,
 	[yap_cv_mpe=no])
 
-AC_ARG_WITH(lam,
-	[ --with-lam[=DIR]           use LAM MPI library in DIR],
-	if test "$withval" = yes; then
-	        yap_cv_lam=yes
-	elif test "$withval" = no; then
-		yap_cv_lam=no
-	else
-		yap_cv_lam=$with_lam
-		LDFLAGS="$LDFLAGS -L${yap_cv_lam}/lib"
-		CPPFLAGS="$CPPFLAGS -I${yap_cv_lam}/include"
-	fi,
-	[yap_cv_lam=no])
-
 AC_ARG_WITH(heap-space,
 	[ --with-heap-space[=space]  default heap size in Kbytes],
 	if test "$withval" = yes; then
@@ -612,7 +599,9 @@ then
        C_PARSER_FLAGS="-O3 -Wall -Wstrict-prototypes -Wmissing-prototypes $CFLAGS"
        CFLAGS="-O3 -fomit-frame-pointer -Wall -Wstrict-prototypes -Wmissing-prototypes $CFLAGS"
        case "`$CC --version < /dev/null`" in	
-	  *3.4*) CFLAGS="-fno-gcse -fno-crossjumping $CFLAGS" ;;
+	  *3.4*) 
+	    CFLAGS="-fno-gcse -fno-crossjumping $CFLAGS" 
+	  ;;
        esac
        case "$target_cpu" in
         i*86*)
@@ -697,7 +686,6 @@ AC_PROG_LN_S
 AC_PROG_INSTALL
 AC_PROG_RANLIB
 AC_CHECK_TOOL(AR,ar,:)
-AC_CHECK_TOOL(MPI_CC,mpicc,${CC})
 AC_PATH_PROG(INSTALL_INFO,install-info,true,$PATH:/sbin:/usr/sbin:/usr/etc:/usr/local/sbin)
 AC_PATH_PROG(SHELL,sh)
 
@@ -1533,6 +1521,12 @@ dnl Linux has both elf and a.out, in this case we found elf
 	;;
 esac
 
+if test "$CC" = icc
+then
+  MPI_CC="$CC"
+  yap_cv_mpi=no
+fi
+
 if test "$dynamic_loading" = "yes"
 then 
   YAPLIB_CFLAGS="$SHLIB_CFLAGS"
@@ -1643,53 +1637,20 @@ if test "$tabling" = "yes"
 fi
 dnl LAM/MPI interface
 
-LAMOBJS=""
-MPI_OBJS=
-LAM_MPI_CC=${MPI_CC}
-if  test "$yap_cv_lam" != "no" ; then	
-  if test "$yap_cv_lam" != "yes" ; then
-    LAM_MPI_CC="$yap_cv_lam"/bin/mpicc
-    MPI_CC="$yap_cv_lam"/bin/mpicc
-    CPPFLAGS="$CPPFLAGS -I ${yap_cv_lam}/include"
-    LDFLAGS="$LDFLAGS -L${yap_cv_lam}/lib"
-  fi
-  OLD_CC=${CC}	
-  CC=${LAM_MPI_CC}
-  AC_CHECK_HEADER(mpi.h,
-		[LAMOBJS=yap_mpi."$SO"
-                 AC_DEFINE(HAVE_LIBMPI, 1)],
-		[LAMOBJS=""
-                 AC_DEFINE(HAVE_LIBMPI, 0)])
-  CC=${OLD_CC}
-  dnl use mpich library
-elif test "$yap_cv_mpi" != "no"; then
+if test "$yap_cv_mpi" != "no"; then
+    if test "$yap_cv_mpi" != "yes"; then
+      AC_PATH_PROG(MPI_CC,mpicc,true,$PATH:/sbin:/usr/sbin:/usr/etc:/usr/local/sbin)
+    else
+      AC_PATH_PROG(MPI_CC,mpicc,true,$yap_cv_mpi/bin:$PATH:/sbin:/usr/sbin:/usr/etc:/usr/local/sbin)
+    fi
+    MPILDF=`"$MPI_CC" --showme:link`
+    MPICF=`"$MPI_CC" --showme:compile`
+    LIBS="$LIBS $MPILDF"
+    INSTALL_MPI=""
     OLD_CC=${CC}
     CC=${MPI_CC}
-    AC_CHECK_LIB(mpi,MPI_Init,
-		[LAMOBJS=yap_mpi."$SO"
-                 AC_DEFINE(HAVE_LIBMPI, 1)],
-		[LAMOBJS=yap_mpi."$SO"
-                 AC_DEFINE(HAVE_LIBMPI, 0)])
-    if test "$ac_cv_lib_mpi_MPI_Init" = yes
-    then
-	#YAPMPILIB=YapMPI.a
-	MPI_OBJS=mpi.o
-    else
-      AC_CHECK_LIB(mpich,MPI_Init,
-		[AC_DEFINE(HAVE_LIBMPICH, 1)],
-		[AC_DEFINE(HAVE_LIBMPICH, 0)])
-      if test "$ac_cv_lib_mpich_MPI_Init" = yes
-      then
-	#YAPMPILIB=YapMPI.a
-	MPI_OBJS=mpi.o
-      else
-	#YAPMPILIB=
-	MPI_CC=${CC}
-      fi
-    fi
     AC_CHECK_HEADERS(mpi.h)
     CC=${OLD_CC}
-    MPI_LIBS=
     if test "$yap_cv_mpe" != "no"
     then
      OLD_CC=${CC}
@@ -1706,7 +1667,8 @@ elif test "$yap_cv_mpi" != "no"; then
      CC=${OLD_CC}
    fi
 else
-    MPI_CC=${CC}
+  INSTALL_MPI="# "
+  MPI_CC=${CC}
 fi
 
 
@@ -1910,16 +1872,16 @@ AC_SUBST(JAR)
 AC_SUBST(LIBJPL)
 AC_SUBST(IN_UNIX)
 AC_SUBST(YAPMPILIB)
-AC_SUBST(LAM_MPI_CC)
-AC_SUBST(MPI_OBJS)
-AC_SUBST(MPI_LIBS)
+AC_SUBST(INSTALL_MPI)
+AC_SUBST(MPI_CC)
+AC_SUBST(MPILDF)
+AC_SUBST(MPICF)
 AC_SUBST(INSTALL_COMMAND)
 AC_SUBST(INSTALLCLP)
 AC_SUBST(JPLCFLAGS)
 AC_SUBST(JPLLIBS)
 AC_SUBST(JAVALIBS)
 AC_SUBST(JPLCFLAGS)
-AC_SUBST(LAMOBJS)
 AC_SUBST(MAX_WORKERS)
 AC_SUBST(STATIC_MODE)
 AC_SUBST(ENABLE_WINCONSOLE)
@@ -2126,7 +2088,7 @@ AC_CHECK_FUNCS(erf feclearexcept)
 AC_CHECK_FUNCS(fesettrapenable fgetpos finite fpclass ftime ftruncate getcwd getenv)
 AC_CHECK_FUNCS(getexecname)
 AC_CHECK_FUNCS(gethostbyname gethostent gethostid gethostname)
-AC_CHECK_FUNCS(gethrtime getpagesize)
+AC_CHECK_FUNCS(gethrtime getpagesize getpid)
 AC_CHECK_FUNCS(getpwnam getrlimit getrusage gettimeofday getwd)
 AC_CHECK_FUNCS(isatty isnan isinf kill labs link lgamma)
 AC_CHECK_FUNCS(localtime lstat mallinfo)
diff --git a/library/dialect/swi.yap b/library/dialect/swi.yap
index b40c2df1e..612a20330 100644
--- a/library/dialect/swi.yap
+++ b/library/dialect/swi.yap
@@ -46,6 +46,8 @@
 			    selectchk/3,
 			    sublist/2,
 			    sumlist/2,
+			    nth1/4,
+			    nth0/4,
 			    nth1/3,
 			    nth0/3]).
 
diff --git a/library/dialect/swi/INDEX.pl b/library/dialect/swi/INDEX.pl
index e39e0a1e9..c10596e57 100644
--- a/library/dialect/swi/INDEX.pl
+++ b/library/dialect/swi/INDEX.pl
@@ -18,7 +18,9 @@ index(selectchk,3,system,library(dialect/swi)).
 index(sublist,2,system,library(dialect/swi)).
 index(sumlist,2,system,library(dialect/swi)).
 index(nth1,3,system,library(dialect/swi)).
+index(nth1,4,system,library(dialect/swi)).
 index(nth0,3,system,library(dialect/swi)).
+index(nth0,4,system,library(dialect/swi)).
 index(maplist,2,system,library(dialect/swi)).
 index(maplist,3,system,library(dialect/swi)).
 index(maplist,4,system,library(dialect/swi)).
diff --git a/library/lammpi/Makefile.in b/library/lammpi/Makefile.in
index 82f3077a1..877ea3335 100644
--- a/library/lammpi/Makefile.in
+++ b/library/lammpi/Makefile.in
@@ -23,7 +23,7 @@ YAPLIBDIR=@libdir@/Yap
 #
 #
 CC=@CC@
-MPI_CC=@LAM_MPI_CC@
+MPI_CC=@MPI_CC@
 CFLAGS= @SHLIB_CFLAGS@ $(YAP_EXTRAS) $(DEFS) -I$(srcdir) -I../.. -I$(srcdir)/../../include
 #
 #
@@ -37,13 +37,12 @@ RANLIB=@RANLIB@
 srcdir=@srcdir@
 SO=@SO@
 CWD=$(PWD)
-MPILDF=`$(MPI_CC) --showme:link`
-MPICF=`$(MPI_CC) --showme:compile`
+MPILDF=@MPILDF@
+MPICF=@MPICF@
 #
 
 OBJS=yap_mpi.o hash.o prologterms2c.o
-SOBJS=@LAMOBJS@
-#yap_mpi.@SO@
+SOBJS=yap_mpi.@SO@
 
 #in some systems we just create a single object, in others we need to
 # create a libray
diff --git a/os/pl-file.c b/os/pl-file.c
index 4ac3e5b42..ab3d3824a 100755
--- a/os/pl-file.c
+++ b/os/pl-file.c
@@ -5039,10 +5039,66 @@ struct PL_local_data *Yap_InitThreadIO(int wid)
   return p;
 }
 
+#ifdef THREADS
+
+#define COUNT_MUTEX_INITIALIZER(name) \
+ { PTHREAD_MUTEX_INITIALIZER, \
+   name, \
+   0L \
+ }
+
+
+counting_mutex _PL_mutexes[] =
+{ COUNT_MUTEX_INITIALIZER("L_MISC"),
+  COUNT_MUTEX_INITIALIZER("L_ALLOC"),
+  COUNT_MUTEX_INITIALIZER("L_ATOM"),
+  COUNT_MUTEX_INITIALIZER("L_FLAG"),
+  COUNT_MUTEX_INITIALIZER("L_FUNCTOR"),
+  COUNT_MUTEX_INITIALIZER("L_RECORD"),
+  COUNT_MUTEX_INITIALIZER("L_THREAD"),
+  COUNT_MUTEX_INITIALIZER("L_PREDICATE"),
+  COUNT_MUTEX_INITIALIZER("L_MODULE"),
+  COUNT_MUTEX_INITIALIZER("L_TABLE"),
+  COUNT_MUTEX_INITIALIZER("L_BREAK"),
+  COUNT_MUTEX_INITIALIZER("L_FILE"),
+  COUNT_MUTEX_INITIALIZER("L_PLFLAG"),
+  COUNT_MUTEX_INITIALIZER("L_OP"),
+  COUNT_MUTEX_INITIALIZER("L_INIT"),
+  COUNT_MUTEX_INITIALIZER("L_TERM"),
+  COUNT_MUTEX_INITIALIZER("L_GC"),
+  COUNT_MUTEX_INITIALIZER("L_AGC"),
+  COUNT_MUTEX_INITIALIZER("L_STOPTHEWORLD"),
+  COUNT_MUTEX_INITIALIZER("L_FOREIGN"),
+  COUNT_MUTEX_INITIALIZER("L_OS"),
+  COUNT_MUTEX_INITIALIZER("L_LOCALE")
+#ifdef __WINDOWS__
+, COUNT_MUTEX_INITIALIZER("L_DDE")
+, COUNT_MUTEX_INITIALIZER("L_CSTACK")
+#endif
+
+};
+
+static void
+initMutexes( void )
+{ counting_mutex *m;
+  int n = sizeof(_PL_mutexes)/sizeof(*m);
+  int i;
+
+  for(i=0, m=_PL_mutexes; i<n; i++, m++)
+    simpleMutexInit(&m->mutex);
+}
+
+
+#endif
+
+
 static void
 init_yap(void)
 {
   GET_LD
+#ifdef THREADS
+  initMutexes();
+#endif
   /* we need encodings first */
   initCharTypes();
   initPrologFlags();
diff --git a/os/pl-prologflag.c b/os/pl-prologflag.c
index 91d253777..b0d00cfa8 100644
--- a/os/pl-prologflag.c
+++ b/os/pl-prologflag.c
@@ -25,6 +25,7 @@
 #include "pl-incl.h"
 #ifdef __YAP_PROLOG__
 #include "pl-ctype.h"
+#include "eval.h"
 #else
 #include "os/pl-ctype.h"
 #endif
@@ -1049,32 +1050,48 @@ initPrologFlagTable(void)
 void
 initPrologFlags(void)
 { GET_LD
-#ifndef __YAP_PROLOG__
   setPrologFlag("iso",  FT_BOOL, FALSE, PLFLAG_ISO);
+#ifdef __YAP_PROLOG__
+  setPrologFlag("arch", FT_ATOM|FF_READONLY, YAP_ARCH);
+#else
   setPrologFlag("arch", FT_ATOM|FF_READONLY, PLARCH);
+#endif
 #if __WINDOWS__
   setPrologFlag("windows",	FT_BOOL|FF_READONLY, TRUE, 0);
 #endif
+#ifndef __YAP_PROLOG__
   setPrologFlag("version",	FT_INTEGER|FF_READONLY, PLVERSION);
   setPrologFlag("dialect", FT_ATOM|FF_READONLY, "swi");
   if ( systemDefaults.home )
     setPrologFlag("home", FT_ATOM|FF_READONLY, systemDefaults.home);
   if ( GD->paths.executable )
     setPrologFlag("executable", FT_ATOM|FF_READONLY, GD->paths.executable);
+#else
+  setPrologFlag("dialect", FT_ATOM|FF_READONLY, "yap");
+  setPrologFlag("home", FT_ATOM|FF_READONLY, YAP_ROOTDIR);
+  if (GLOBAL_argv && GLOBAL_argv[0]) {
+    Yap_TrueFileName (GLOBAL_argv[0], LOCAL_FileNameBuf, FALSE);
+    setPrologFlag("executable", FT_ATOM|FF_READONLY, LOCAL_FileNameBuf);
+  } else
+    setPrologFlag("executable", FT_ATOM|FF_READONLY, Yap_FindExecutable());
+#endif
 #if defined(HAVE_GETPID) || defined(EMULATE_GETPID)
   setPrologFlag("pid", FT_INTEGER|FF_READONLY, getpid());
 #endif
   setPrologFlag("optimise", FT_BOOL, GD->cmdline.optimise, PLFLAG_OPTIMISE);
   setPrologFlag("generate_debug_info", FT_BOOL,
 		truePrologFlag(PLFLAG_DEBUGINFO), PLFLAG_DEBUGINFO);
+#ifndef __YAP_PROLOG__
   setPrologFlag("last_call_optimisation", FT_BOOL, TRUE, PLFLAG_LASTCALL);
   setPrologFlag("warn_override_implicit_import", FT_BOOL, TRUE,
 		PLFLAG_WARN_OVERRIDE_IMPLICIT_IMPORT);
+#endif
   setPrologFlag("c_cc",	     FT_ATOM, C_CC);
   setPrologFlag("c_libs",    FT_ATOM, C_LIBS);
   setPrologFlag("c_libplso", FT_ATOM, C_LIBPLSO);
   setPrologFlag("c_ldflags", FT_ATOM, C_LDFLAGS);
   setPrologFlag("c_cflags",  FT_ATOM, C_CFLAGS);
+#ifndef __YAP_PROLOG__
 #if defined(O_LARGEFILES) || SIZEOF_LONG == 8
   setPrologFlag("large_files", FT_BOOL|FF_READONLY, TRUE, 0);
 #endif
@@ -1083,6 +1100,7 @@ initPrologFlags(void)
 #ifdef O_ATOMGC
   setPrologFlag("agc_margin",FT_INTEGER,	       GD->atoms.margin);
 #endif
+#endif
 #if defined(HAVE_DLOPEN) || defined(HAVE_SHL_LOAD) || defined(EMULATE_DLOPEN)
   setPrologFlag("open_shared_object",	  FT_BOOL|FF_READONLY, TRUE, 0);
   setPrologFlag("shared_object_extension",	  FT_ATOM|FF_READONLY, SO_EXT);
@@ -1123,8 +1141,13 @@ initPrologFlags(void)
   setPrologFlag("max_integer",	   FT_INT64|FF_READONLY, PLMAXINT);
   setPrologFlag("min_integer",	   FT_INT64|FF_READONLY, PLMININT);
 #endif
+#ifndef __YAP_PROLOG__
   setPrologFlag("max_tagged_integer", FT_INTEGER|FF_READONLY, PLMAXTAGGEDINT);
   setPrologFlag("min_tagged_integer", FT_INTEGER|FF_READONLY, PLMINTAGGEDINT);
+#else
+  setPrologFlag("max_tagged_integer", FT_INTEGER|FF_READONLY, Int_MAX);
+  setPrologFlag("min_tagged_integer", FT_INTEGER|FF_READONLY, Int_MIN);
+#endif
 #ifdef O_GMP
   setPrologFlag("bounded",		   FT_BOOL|FF_READONLY,	   FALSE, 0);
 #ifdef __GNU_MP__
@@ -1148,6 +1171,7 @@ initPrologFlags(void)
   setPrologFlag("occurs_check", FT_ATOM, "false");
   setPrologFlag("access_level", FT_ATOM, "user");
   setPrologFlag("double_quotes", FT_ATOM, "codes");
+#ifndef __YAP_PROLOG__
   setPrologFlag("unknown", FT_ATOM, "error");
   setPrologFlag("debug", FT_BOOL, FALSE, 0);
   setPrologFlag("verbose", FT_ATOM|FF_KEEP, GD->options.silent ? "silent" : "normal");
@@ -1161,6 +1185,7 @@ initPrologFlags(void)
   setPrologFlag("toplevel_prompt", FT_ATOM, "~m~d~l~! ?- ");
   setPrologFlag("file_name_variables", FT_BOOL, FALSE, PLFLAG_FILEVARS);
   setPrologFlag("fileerrors", FT_BOOL, TRUE, PLFLAG_FILEERRORS);
+#endif
 #ifdef __unix__
   setPrologFlag("unix", FT_BOOL|FF_READONLY, TRUE, 0);
 #endif
@@ -1184,7 +1209,6 @@ initPrologFlags(void)
     setPrologFlag("compiled_at", FT_ATOM|FF_READONLY, buf);
   }
 #endif
-#endif /* YAP_PROLOG */
   /* Flags copied by YAP */
   setPrologFlag("optimise", FT_BOOL, GD->cmdline.optimise, PLFLAG_OPTIMISE);
   /* FLAGS used by PLStream */
diff --git a/os/pl-read.c b/os/pl-read.c
index 7ccf9413f..e4ed6b1ff 100644
--- a/os/pl-read.c
+++ b/os/pl-read.c
@@ -997,6 +997,9 @@ atom_to_term(term_t atom, term_t term, term_t bindings)
 { GET_LD
   PL_chars_t txt;
 
+    { FILE *f=fopen("/home/vsc/coutput.txt", "append");
+    fprintf(f, "IN: %ld\n", bindings);
+    fclose(f); }
   if ( !bindings && PL_is_variable(atom) ) /* term_to_atom(+, -) */
   { char buf[1024];
     size_t bufsize = sizeof(buf);
@@ -1015,6 +1018,9 @@ atom_to_term(term_t atom, term_t term, term_t bindings)
     txt.storage = PL_CHARS_HEAP;
     txt.encoding = ENC_UTF8;
     txt.canonical = FALSE;
+    { FILE *f=fopen("/home/vsc/coutput.txt", "append");
+    fprintf(f, "SUCCESS: %s\n", buf);
+    fclose(f); }
     rval = PL_unify_text(atom, 0, &txt, PL_ATOM);
 
     Sclose(stream);
diff --git a/os/pl-stream.c b/os/pl-stream.c
index 4bc122cdf..fe165728f 100755
--- a/os/pl-stream.c
+++ b/os/pl-stream.c
@@ -2255,9 +2255,11 @@ Svsprintf(char *buf, const char *fm, va_list args)
 int
 Svdprintf(const char *fm, va_list args)
 { int rval;
-  IOSTREAM *s = Serror;
+    IOSTREAM *s = Serror;
+  //IOSTREAM *s = Sopen_file("/home/vsc/cout.txt", "append");
 
-  Slock(s);
+
+  //Slock(s);
   rval = Svfprintf(s, fm, args);
 #if defined(_DEBUG) && defined(__WINDOWS__)
   Sputc('\0', s);
@@ -2266,7 +2268,8 @@ Svdprintf(const char *fm, va_list args)
 #endif
   if ( Sflush(s) != 0 )
     rval = -1;
-  Sunlock(s);
+  //Sunlock(s);
+  //Sclose(s);
 
   return rval;
 }
diff --git a/os/pl-thread.h b/os/pl-thread.h
index efcf1246a..6024226df 100755
--- a/os/pl-thread.h
+++ b/os/pl-thread.h
@@ -107,8 +107,25 @@ compile-time
 	  simpleMutexUnlock(&(cm)->mutex); \
 	} while(0)
 
+//#define O_DEBUG_MT
+#ifdef O_DEBUG_MT
+#define PL_LOCK(id) \
+	do { Sdprintf("[%d] %s:%d: LOCK(%s)\n", \
+		      pthread_self(),		     \
+		      __BASE_FILE__, __LINE__, #id); \
+             countingMutexLock(&_PL_mutexes[id]); \
+	   } while(0)
+#define PL_UNLOCK(id) \
+	do { Sdprintf("[%d] %s:%d: UNLOCK(%s)\n", \
+		      pthread_self(), \
+		      __BASE_FILE__, __LINE__, #id); \
+	     countingMutexUnlock(&_PL_mutexes[id]); \
+	   } while(0)
+#else
 #define PL_LOCK(id)   IF_MT(id, countingMutexLock(&_PL_mutexes[id]))
 #define PL_UNLOCK(id) IF_MT(id, countingMutexUnlock(&_PL_mutexes[id]))
+#endif
+#undef O_DEBUG_MT
 
 #define IOLOCK  recursiveMutex
 
diff --git a/pl/boot.yap b/pl/boot.yap
index 1f341ca46..28ced225c 100755
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -94,22 +94,15 @@ true :- true.
 
 '$init_globals' :-
 	'$init_consult',
-	nb_setval('$chr_toplevel_show_store',false),
 	nb_setval('$break',0),
-	% '$set_read_error_handler'(error), let the user do that
-	nb_setval('$open_expands_filename',true),
-	nb_setval('$trace',off),
+	% '$set_read_error_handler'(error), let the user do that 
 	nb_setval('$system_mode',off),
-	nb_setval('$chr_toplevel_show_store',false),
-	nb_setval('$assert_all',off),
-	nb_setval('$if_skip_mode',no_skip),
-	b_setval('$spy_glist',[]),
-	nb_setval('$spy_gn',1),
-	nb_setval('$debug_run',off),
-	nb_setval('$debug_jump',off).
+	nb_setval('$chr_toplevel_show_store',false).
 
 '$init_consult' :-
+	set_value('$open_expands_filename',true),
 	set_value('$lf_verbose',informational),
+	nb_setval('$assert_all',off),
 	nb_setval('$if_level',0),
 	nb_setval('$endif',off),
 	nb_setval('$consulting_file',[]),
@@ -1263,7 +1256,7 @@ catch_ball(C, C).
 	 '$execute_outside_system_mode'(G2, M, CP)
 	).
 '$execute_outside_system_mode'(G, M, CP) :-
-	nb_getval('$trace', on), !,
+	'$nb_getval'('$trace', on, fail), !,
 	(
 	   '$$save_by'(CP1),
 	  '$do_spy'(G, M, CP, meta_creep),
diff --git a/pl/consult.yap b/pl/consult.yap
index 4731c3d8c..cb5af77e8 100755
--- a/pl/consult.yap
+++ b/pl/consult.yap
@@ -923,20 +923,20 @@ absolute_file_name(File,Opts,TrueFileName) :-
 	'$get_if'(Level0),
 	Level is Level0 + 1,
 	nb_setval('$if_level',Level),
-	nb_getval('$endif',OldEndif),
-	nb_getval('$if_skip_mode',Mode),
+	'$nb_getval'('$endif', OldEndif, OldEndif=top),
+	'$nb_getval'('$if_skip_mode', Mode, Mode=run),
 	nb_setval('$endif',elif(Level,OldEndif,Mode)),
 	fail.
 % we are in skip mode, ignore....
 '$if'(Goal,_) :-
-	nb_getval('$endif',elif(Level, OldEndif, skip)), !,
+	'$nb_getval'('$endif',elif(Level, OldEndif, skip), fail), !,
 	nb_setval('$endif',endif(Level, OldEndif, skip)).	
 % we are in non skip mode, check....
 '$if'(Goal,_) :-
 	('$if_call'(Goal)
 	    ->
 	 % we will execute this branch, and later enter skip
-	 nb_getval('$endif',elif(Level,OldEndif,Mode)),
+	 '$nb_getval'('$endif', elif(Level,OldEndif,Mode), fail),
 	 nb_setval('$endif',endif(Level,OldEndif,Mode))
 	;
 	 % we are now in skip, but can start an elif.
diff --git a/pl/control.yap b/pl/control.yap
index 131a93301..07fd95982 100644
--- a/pl/control.yap
+++ b/pl/control.yap
@@ -320,6 +320,7 @@ b_getval(GlobalVariable, Val) :-
 	debugger state */
 
 break :-
+	'$init_debugger',
 	nb_getval('$system_mode',SystemMode),
 	nb_getval('$trace',Trace),
 	nb_setval('$trace',off),
diff --git a/pl/debug.yap b/pl/debug.yap
index f3ac908bf..cf772b486 100644
--- a/pl/debug.yap
+++ b/pl/debug.yap
@@ -11,7 +11,7 @@
 * File:		debug.pl						 *
 * Last rev:								 *
 * mods:									 *
-* comments:	YAP's debugger						 *
+* comments:	YAP debugger						 *
 *									 *
 *************************************************************************/
 
@@ -23,6 +23,16 @@
 
 :- op(900,fx,[spy,nospy]).
 
+'$init_debugger' :-
+        nb_getval('$trace', _, fail), !.
+'$init_debugger' :-
+	nb_setval('$trace',off),
+	nb_setval('$if_skip_mode',no_skip),
+	b_setval('$spy_glist',[]),
+	nb_setval('$spy_gn',1),
+	nb_setval('$debug_run',off),
+	nb_setval('$debug_jump',off).
+
 
 % First part : setting and reseting spy points
 
@@ -123,6 +133,7 @@
 	recorded('$spy','$spy'(G,M),_), !.
 
 spy Spec :-
+	'$init_debugger',
 	prolog:debug_action_hook(spy(Spec)), !.
 spy L :-
 	'$current_module'(M),
@@ -130,6 +141,7 @@ spy L :-
 spy _ :- debug.
 
 nospy Spec :-
+	'$init_debugger',
 	prolog:debug_action_hook(nospy(Spec)), !.
 nospy L :-
 	'$current_module'(M),
@@ -137,6 +149,7 @@ nospy L :-
 nospy _.
 
 nospyall :-
+	'$init_debugger',
 	prolog:debug_action_hook(nospyall), !.
 nospyall :-
 	recorded('$spy','$spy'(T,M),_), functor(T,F,N), '$suspy'(F/N,nospy,M), fail.
@@ -145,6 +158,7 @@ nospyall.
 % debug mode -> debug flag = 1
 
 debug :-
+	'$init_debugger',
 	( nb_getval('$spy_gn',L) -> true ; nb_setval('$spy_gn',1) ),
 	'$start_debugging'(on),
 	print_message(informational,debug(debug)).
@@ -159,6 +173,7 @@ debug :-
 	nb_setval('$debug_jump',false).
 	
 nodebug :-
+	'$init_debugger',
 	'$debug_on'(false),
 	nb_setval('$trace',off),
 	print_message(informational,debug(off)).
@@ -168,7 +183,8 @@ nodebug :-
  %
 	
 trace :- 
-	nb_getval('$trace',on), !.
+	'$init_debugger',
+	'$nb_getval'('$trace', on, fail), !.
 trace :-
 	nb_setval('$trace',on),
 	'$start_debugging'(on),
@@ -176,7 +192,7 @@ trace :-
 	'$meta_creep'.
 
 '$do_trace' :- 
-	nb_getval('$trace',on), !.
+	'$nb_getval'('$trace', on, fail), !.
 '$do_trace' :-
 	nb_setval('$trace',on),
 	'$start_debugging'(on),
@@ -184,6 +200,7 @@ trace :-
 	'$creep'.
 
 notrace :-
+	'$init_debugger',
 	nodebug.
 
 /*-----------------------------------------------------------------------------
@@ -196,6 +213,7 @@ notrace :-
 leash(X) :- var(X),
 	'$do_error'(instantiation_error,leash(X)).
 leash(X) :-
+	'$init_debugger',
 	'$leashcode'(X,Code),
 	set_value('$leash',Code),
 	'$show_leash'(informational,Code), !.
@@ -243,6 +261,7 @@ leash(X) :-
 
 
 debugging :-
+	'$init_debugger',
 	prolog:debug_action_hook(nospyall), !.
 debugging :-
 	( '$debug_on'(true) ->
diff --git a/pl/flags.yap b/pl/flags.yap
index 2b1ed518a..58e8739fa 100755
--- a/pl/flags.yap
+++ b/pl/flags.yap
@@ -58,9 +58,6 @@ yap_flag(autoload,false) :-
 % do or do not machine code
 yap_flag(argv,L) :- '$argv'(L).
 
-% do or do not machine code
-yap_flag(executable,L) :- '$executable'(L).
-
 % hide/unhide atoms
 yap_flag(hide,Atom) :- !, hide(Atom).
 yap_flag(unhide,Atom) :- !, unhide(Atom).
@@ -212,16 +209,6 @@ yap_flag(associate,X) :-
 yap_flag(associate,X) :-
 	'$do_error'(type_error(atom,X),associate(X)).
 
-yap_flag(bounded,X) :-
-	var(X), !,
-	'$access_yap_flags'(0, X1),
-	'$transl_to_true_false'(X1,X).
-yap_flag(bounded,X) :-
-	(X = true ; X = false), !,
-	'$do_error'(permission_error(modify,flag,bounded),yap_flag(bounded,X)).
-yap_flag(bounded,X) :-
-	'$do_error'(domain_error(flag_value,bounded+X),yap_flag(bounded,X)).
-
 % do or do not indexation
 yap_flag(index,X) :- var(X),
 	'$access_yap_flags'(19, X1),
@@ -244,9 +231,6 @@ yap_flag(index_sub_term_search_depth,X,X)  :-
 yap_flag(index_sub_term_search_depth,X,X) :-
 	'$do_error'(domain_error(out_of_range,index_sub_term_search_depth+X),yap_flag(index_sub_term_search_depth,X)).
 
-yap_flag(home,X) :-
-	'$yap_home'(X).
-
 % should match definitions in Yap.h
 '$transl_to_index_mode'(0, off).
 '$transl_to_index_mode'(1, single).
@@ -312,58 +296,12 @@ yap_flag(integer_rounding_function,X) :-
 yap_flag(integer_rounding_function,X) :-
 	'$do_error'(domain_error(flag_value,integer_rounding_function+X),yap_flag(integer_rounding_function,X)).
 
-yap_flag(max_arity,X) :-
-	var(X), !,
-	'$access_yap_flags'(1, X1),
-	'$transl_to_arity'(X1,X).
-yap_flag(max_arity,X) :-
-	integer(X), X > 0, !,
-	'$do_error'(permission_error(modify,flag,max_arity),yap_flag(max_arity,X)).
-yap_flag(max_arity,X) :-
-	'$do_error'(domain_error(flag_value,max_arity+X),yap_flag(max_arity,X)).
-
 yap_flag(version,X) :-
 	var(X), !,
 	get_value('$version_name',X).
 yap_flag(version,X) :-
 	'$do_error'(permission_error(modify,flag,version),yap_flag(version,X)).
 
-yap_flag(max_integer,X) :-
-	var(X), !,
-	'$access_yap_flags'(0, 1),
-	'$access_yap_flags'(3, X).
-yap_flag(max_integer,X) :-
-	integer(X), X > 0, !,
-	'$do_error'(permission_error(modify,flag,max_integer),yap_flag(max_integer,X)).
-yap_flag(max_integer,X) :-
-	'$do_error'(domain_error(flag_value,max_integer+X),yap_flag(max_integer,X)).
-
-yap_flag(max_tagged_integer,X) :-
-	'$max_tagged_integer'(X), !.
-yap_flag(max_tagged_integer,X) :-			       
-	integer(X), X > 0, !,
-	'$do_error'(permission_error(modify,flag,max_tagged_integer),yap_flag(max_tagged_integer,X)).
-yap_flag(max_tagged_integer,X) :-
-	'$do_error'(domain_error(flag_value,max_tagged_integer+X),yap_flag(max_tagged_integer,X)).
-
-yap_flag(min_integer,X) :-
-	var(X), !,
-	'$access_yap_flags'(0, 1),
-	'$access_yap_flags'(4, X).
-yap_flag(min_integer,X) :-
-	integer(X), X < 0, !,
-	'$do_error'(permission_error(modify,flag,min_integer),yap_flag(min_integer,X)).
-yap_flag(min_integer,X) :-
-	'$do_error'(domain_error(flag_value,min_integer+X),yap_flag(min_integer,X)).
-
-yap_flag(min_tagged_integer,X) :-
-	'$min_tagged_integer'( X), !.
-yap_flag(min_tagged_integer,X) :-
-	integer(X), X > 0, !,
-	'$do_error'(permission_error(modify,flag,min_tagged_integer),yap_flag(min_tagged_integer,X)).
-yap_flag(min_tagged_integer,X) :-
-	'$do_error'(domain_error(flag_value,min_tagged_integer+X),yap_flag(min_tagged_integer,X)).
-
 /* ISO Core Revision DTR: new float flags
 
 yap_flag(float_mantissa_digits,X) :-
@@ -419,16 +357,6 @@ yap_flag(char_conversion,X) :-
 yap_flag(char_conversion,X) :-
 	'$do_error'(domain_error(flag_value,char_conversion+X),yap_flag(char_conversion,X)).
 
-yap_flag(double_quotes,X) :-
-	var(X), !,
-	'$access_yap_flags'(6, X1),
-	'$transl_to_trl_types'(X1,X).
-yap_flag(double_quotes,X) :-
-	'$transl_to_trl_types'(X1,X), !,
-	'$set_yap_flags'(6,X1).
-yap_flag(double_quotes,X) :-
-	'$do_error'(domain_error(flag_value,double_quotes+X),yap_flag(double_quotes,X)).
-
 yap_flag(n_of_integer_keys_in_db,X) :-
 	var(X), !,
 	'$resize_int_keys'(X).
@@ -514,13 +442,6 @@ yap_flag(discontiguous_warnings,X) :-
 yap_flag(discontiguous_warnings,X) :-
 	'$do_error'(domain_error(flag_value,discontiguous_warnings+X),yap_flag(discontiguous_warnings,X)).
 
-yap_flag(occurs_check,X) :-
-	X = false, !.
-yap_flag(occurs_check,true) :- !,
-	fail.
-yap_flag(occurs_check,X) :-
-	'$do_error'(domain_error(flag_value,occurs_check+X),yap_flag(occurs_check,X)).
-
 yap_flag(redefine_warnings,X) :-
 	var(X), !,
 	'$syntax_check_multiple'(X,X).
@@ -536,7 +457,7 @@ yap_flag(redefine_warnings,X) :-
 
 yap_flag(chr_toplevel_show_store,X) :-
 	var(X), !,
-	nb_getval('$chr_toplevel_show_store',X).
+	'$nb_getval'('$chr_toplevel_show_store', X, fail).
 yap_flag(chr_toplevel_show_store,X) :-
 	(X = true ; X = false), !,
 	nb_setval('$chr_toplevel_show_store',X).
@@ -581,8 +502,6 @@ yap_flag(system_options,X) :-
 	'$swi_current_prolog_flag'(readline, true).
 '$system_options'(tabling) :-
 	\+ '$undefined'('$c_table'(_,_,_), prolog).
-'$system_options'(threads) :-
-	\+ '$no_threads'.
 '$system_options'(wam_profiler) :-
 	\+ '$undefined'(reset_op_counters, prolog).
 	
@@ -630,14 +549,6 @@ yap_flag(toplevel_hook,G) :-
 yap_flag(toplevel_hook,G) :- !,
 	'$set_toplevel_hook'(G).
 
-yap_flag(unix,true) :-
-	'$unix', !.
-yap_flag(unix,false).
-
-yap_flag(windows,true) :-
-	'$win32', !.
-yap_flag(windows,false).
-
 yap_flag(shared_object_search_path,P) :-
 	'$ld_path'(P).
 
@@ -788,35 +699,19 @@ yap_flag(max_threads,X) :-
 yap_flag(max_threads,X) :-
 	'$do_error'(domain_error(flag_value,max_threads+X),yap_flag(max_threads,X)).
 
-yap_flag(address_bits,X) :-
-	var(X), !,
-	'$address_bits'(X).
-yap_flag(address_bits,X) :-
-	integer(X), X > 0, !,
-	'$do_error'(permission_error(modify,flag,address_bits),yap_flag(address_bits,X)).
-yap_flag(address_bits,X) :-
-	'$do_error'(domain_error(flag_value,address_bits+X),yap_flag(address_bits,X)).
-
-yap_flag(dialect,yap).
-
-'$yap_system_flag'(address_bits).
 '$yap_system_flag'(agc_margin).
 '$yap_system_flag'(answer_format).
 '$yap_system_flag'(argv).
 '$yap_system_flag'(autoload).
-'$yap_system_flag'(bounded).
 '$yap_system_flag'(char_conversion).
 '$yap_system_flag'(character_escapes).
 '$yap_system_flag'(chr_toplevel_show_store).
 '$yap_system_flag'(debug).
 '$yap_system_flag'(debug_on_error    ).
 '$yap_system_flag'(debugger_print_options).
-'$yap_system_flag'(dialect).
 '$yap_system_flag'(discontiguous_warnings).
 '$yap_system_flag'(dollar_as_lower_case).
 '$yap_system_flag'(double_quotes).
-% '$yap_system_flag'(encoding).
-'$yap_system_flag'(executable).
 %		V = fast  ;
 % '$yap_system_flag'(file_name_variables).
 % '$yap_system_flag'(fileerrors ).
@@ -830,7 +725,6 @@ yap_flag(dialect,yap).
 '$yap_system_flag'(gc_trace    ).
 '$yap_system_flag'(generate_debug_info    ).
 %	    V = hide  ;
-'$yap_system_flag'(home ).
 '$yap_system_flag'(host_type ).
 '$yap_system_flag'(index).
 '$yap_system_flag'(index_sub_term_search_depth).
@@ -838,15 +732,9 @@ yap_flag(dialect,yap).
 '$yap_system_flag'(informational_messages).
 '$yap_system_flag'(integer_rounding_function).
 '$yap_system_flag'(language).
-'$yap_system_flag'(max_arity).
-'$yap_system_flag'(max_integer).
-'$yap_system_flag'(max_tagged_integer).
 '$yap_system_flag'(max_workers).
 '$yap_system_flag'(max_threads).
-'$yap_system_flag'(min_integer).
-'$yap_system_flag'(min_tagged_integer).
 '$yap_system_flag'(n_of_integer_keys_in_db).
-'$yap_system_flag'(occurs_check).
 '$yap_system_flag'(open_expands_filename).
 '$yap_system_flag'(open_shared_object).
 % '$yap_system_flag'(optimise).
@@ -866,7 +754,6 @@ yap_flag(dialect,yap).
 '$yap_system_flag'(toplevel_hook).
 '$yap_system_flag'(toplevel_print_options).
 '$yap_system_flag'(typein_module).
-'$yap_system_flag'(unix).
 '$yap_system_flag'(unknown).
 '$yap_system_flag'(update_semantics).
 '$yap_system_flag'(user_error).
@@ -878,7 +765,6 @@ yap_flag(dialect,yap).
 '$yap_system_flag'(verbose_load).
 '$yap_system_flag'(verbose_auto_load).
 '$yap_system_flag'(version).
-'$yap_system_flag'(windows).
 '$yap_system_flag'(write_strings).
 
 '$show_yap_flag_opts'(V,Out) :-
@@ -957,10 +843,6 @@ yap_flag(dialect,yap).
 '$transl_to_rounding_function'(0,toward_zero).
 '$transl_to_rounding_function'(1,down).
 
-'$transl_to_trl_types'(0,chars).
-'$transl_to_trl_types'(1,codes).
-'$transl_to_trl_types'(2,atom).
-
 '$yap_flag_show_gc_tracing'(true, _, _, on) :- !.
 '$yap_flag_show_gc_tracing'(_, true, _, verbose) :- !.
 '$yap_flag_show_gc_tracing'(_, _, on, very_verbose) :- !.
diff --git a/pl/threads.yap b/pl/threads.yap
index 774c7c20f..f00257dc2 100644
--- a/pl/threads.yap
+++ b/pl/threads.yap
@@ -364,6 +364,7 @@ thread_exit(Term) :-
 	fail.
 '$run_at_thread_exit'(Id0) :-
 	recorded('$thread_exit_hook',[Id0|Hook],R), erase(R),
+	open('/home/vsc/coutput.txt', append, W), writeln(hook:Hook), close(W),
 	catch(once(Hook),_,fail),
 	fail.
 '$run_at_thread_exit'(_).
@@ -374,7 +375,8 @@ thread_at_exit(Goal) :-
 	recordz('$thread_exit_hook',[Id0|Goal],_).
 
 current_thread(Id, Status) :-
-	thread_property(Id, status(Status)).
+	catch(thread_property(Id, status(Status)),
+	  error(existence_error(_,_),_), fail).
 
 
 '$thread_id_alias'(Id, Alias) :-
diff --git a/pl/yio.yap b/pl/yio.yap
index 6add6ea54..5cc5e3b01 100644
--- a/pl/yio.yap
+++ b/pl/yio.yap
@@ -368,12 +368,12 @@ stream_position_data(Prop, Term, Value) :-
 
 
 '$default_expand'(Expand) :-
-	nb_getval('$open_expands_filename',Expand).
+	get_value('$open_expands_filename',Expand).
 
 '$set_default_expand'(true) :- !,
-	nb_setval('$open_expands_filename',true).
+	set_value('$open_expands_filename',true).
 '$set_default_expand'(false) :- !,
-	nb_setval('$open_expands_filename',false).
+	set_value('$open_expands_filename',false).
 '$set_default_expand'(V) :- !,
 	'$do_error'(domain_error(flag_value,V),yap_flag(open_expands_file_name,X)).