diff --git a/C/sysbits.c b/C/sysbits.c
index ef4db300c..0f972bf40 100644
--- a/C/sysbits.c
+++ b/C/sysbits.c
@@ -1124,35 +1124,31 @@ InteractSIGINT(int ch) {
       siglongjmp (Yap_RestartEnv, 1);
 #endif
     }
-    return(-1);
+    return -1;
   case 'c':
     /* continue */
-    return(1);
+    return 1;
   case 'd':
+    Yap_signal (YAP_DEBUG_SIGNAL);
     /* enter debug mode */
-    Yap_PutValue (Yap_LookupAtom ("debug"), MkIntTerm (1));
-    return(1);
+    return 1;
   case 'e':
     /* exit */
     Yap_exit(0);
-    return(-1);
+    return -1;
   case 't':
     /* start tracing */
-    Yap_PutValue (Yap_LookupAtom ("debug"), MkIntTerm (1));
-    Yap_PutValue (Yap_LookupAtom ("spy_sl"), MkIntTerm (0));
-    Yap_PutValue (Yap_FullLookupAtom ("$trace"), MkIntTerm (1));
-    yap_flags[SPY_CREEP_FLAG] = 1;
-    Yap_signal (YAP_CREEP_SIGNAL);
-    return(1);
+    Yap_signal (YAP_TRACE_SIGNAL);
+    return 1;
 #ifdef LOW_LEVEL_TRACER
   case 'T':
     toggle_low_level_trace();
-    return(1);
+    return 1;
 #endif
   case 's':
     /* show some statistics */
-    Yap_show_statistics();
-    return(1);
+    Yap_signal (YAP_STATISTICS_SIGNAL);
+    return 1;
   case EOF:
     return(0);
     break;
@@ -2166,6 +2162,31 @@ p_first_signal(void)
     UNLOCK(SignalLock);
     return Yap_unify(ARG1, MkAtomTerm(Yap_LookupAtom("sig_creep")));
   }
+  if (ActiveSignals & YAP_TRACE_SIGNAL) {
+    ActiveSignals &= ~YAP_TRACE_SIGNAL;
+    UNLOCK(SignalLock);
+    return Yap_unify(ARG1, MkAtomTerm(Yap_LookupAtom("sig_trace")));
+  }
+  if (ActiveSignals & YAP_DEBUG_SIGNAL) {
+    ActiveSignals &= ~YAP_DEBUG_SIGNAL;
+    UNLOCK(SignalLock);
+    return Yap_unify(ARG1, MkAtomTerm(Yap_LookupAtom("sig_debug")));
+  }
+  if (ActiveSignals & YAP_BREAK_SIGNAL) {
+    ActiveSignals &= ~YAP_BREAK_SIGNAL;
+    UNLOCK(SignalLock);
+    return Yap_unify(ARG1, MkAtomTerm(Yap_LookupAtom("sig_break")));
+  }
+  if (ActiveSignals & YAP_STACK_DUMP_SIGNAL) {
+    ActiveSignals &= ~YAP_STACK_DUMP_SIGNAL;
+    UNLOCK(SignalLock);
+    return Yap_unify(ARG1, MkAtomTerm(Yap_LookupAtom("sig_stack_dump")));
+  }
+  if (ActiveSignals & YAP_STATISTICS_SIGNAL) {
+    ActiveSignals &= ~YAP_STATISTICS_SIGNAL;
+    UNLOCK(SignalLock);
+    return Yap_unify(ARG1, MkAtomTerm(Yap_LookupAtom("sig_statistics")));
+  }
   UNLOCK(SignalLock);
   return FALSE;
 }
@@ -2195,6 +2216,21 @@ p_continue_signals(void)
   if (ActiveSignals & YAP_CREEP_SIGNAL) {
     Yap_signal(YAP_CREEP_SIGNAL);
   }
+  if (ActiveSignals & YAP_TRACE_SIGNAL) {
+    Yap_signal(YAP_TRACE_SIGNAL);
+  }
+  if (ActiveSignals & YAP_DEBUG_SIGNAL) {
+    Yap_signal(YAP_DEBUG_SIGNAL);
+  }
+  if (ActiveSignals & YAP_BREAK_SIGNAL) {
+    Yap_signal(YAP_BREAK_SIGNAL);
+  }
+  if (ActiveSignals & YAP_STACK_DUMP_SIGNAL) {
+    Yap_signal(YAP_STACK_DUMP_SIGNAL);
+  }
+  if (ActiveSignals & YAP_STATISTICS_SIGNAL) {
+    Yap_signal(YAP_STATISTICS_SIGNAL);
+  }
   return TRUE;
 }
 
diff --git a/m4/Yap.h.m4 b/m4/Yap.h.m4
index b3d3ae039..15c6cb343 100644
--- a/m4/Yap.h.m4
+++ b/m4/Yap.h.m4
@@ -10,7 +10,7 @@
 * File:		Yap.h.m4						 *
 * mods:									 *
 * comments:	main header file for YAP				 *
-* version:      $Id: Yap.h.m4,v 1.70 2004-10-06 16:55:48 vsc Exp $	 *
+* version:      $Id: Yap.h.m4,v 1.71 2004-10-08 17:20:03 vsc Exp $	 *
 *************************************************************************/
 
 #include "config.h"
@@ -564,7 +564,12 @@ typedef enum {
   YAP_ITI_SIGNAL     =  0x80,		/* received inter thread signal */
   YAP_TROVF_SIGNAL   = 0x100,		/* received trail overflow */
   YAP_CDOVF_SIGNAL   = 0x200,		/* received code overflow */
-  YAP_STOVF_SIGNAL   = 0x400		/* received stack overflow */
+  YAP_STOVF_SIGNAL   = 0x400,		/* received stack overflow */
+  YAP_TRACE_SIGNAL   = 0x800,		/* received start trace */
+  YAP_DEBUG_SIGNAL   = 0x1000,		/* received start debug */
+  YAP_BREAK_SIGNAL   = 0x2000,		/* received break signal */
+  YAP_STACK_DUMP_SIGNAL= 0x4000,	/* received stack dump signal */
+  YAP_STATISTICS_SIGNAL= 0x8000		/* received statistics */
 } yap_signals;
 
 #define NUMBER_OF_YAP_FLAGS     INDEXING_MODE_FLAG+1
diff --git a/pl/signals.yap b/pl/signals.yap
index fca41918c..188d16b34 100644
--- a/pl/signals.yap
+++ b/pl/signals.yap
@@ -38,7 +38,30 @@
 	% if more signals alive, set creep flag
 	'$continue_signals',
 	'$current_module'(M0),
-	'$execute0'((Goal,M:G),M0).
+	'$execute0'(G,M0).
+'$do_signal'(sig_trace, G) :-
+	'$continue_signals',
+	trace.
+'$do_signal'(sig_debug, G) :-
+	'$continue_signals',
+	'$current_module'(M0),
+	debug,
+	'$execute0'(G,M0).
+'$do_signal'(sig_break, G) :-
+	'$continue_signals',
+	'$current_module'(M0),
+	break,
+	'$execute0'(G,M0).
+'$do_signal'(sig_statistics, G) :-
+	'$continue_signals',
+	'$current_module'(M0),
+	statistics,
+	'$execute0'(G,M0).
+'$do_signal'(sig_stack_dump, G) :-
+	'$continue_signals',
+	'$current_module'(M0),
+	'$stack_dump',
+	'$execute0'(G,M0).
 % Unix signals
 '$do_signal'(sig_alarm, G) :-
 	'$signal_handler'(sig_alarm, G).