diff --git a/BasiliskII/src/Unix/main_unix.cpp b/BasiliskII/src/Unix/main_unix.cpp
index 9653ed52..1ac70743 100644
--- a/BasiliskII/src/Unix/main_unix.cpp
+++ b/BasiliskII/src/Unix/main_unix.cpp
@@ -291,6 +291,68 @@ static void sigsegv_dump_state(sigsegv_address_t fault_address, sigsegv_address_
 }
 
 
+/*
+ *  Update virtual clock and trigger interrupts if necessary
+ */
+
+#ifdef USE_CPU_EMUL_SERVICES
+static uint64 n_check_ticks = 0;
+static uint64 emulated_ticks_start = 0;
+static uint64 emulated_ticks_count = 0;
+static int64 emulated_ticks_current = 0;
+static int32 emulated_ticks_quantum = 1000;
+int32 emulated_ticks = emulated_ticks_quantum;
+
+void cpu_do_check_ticks(void)
+{
+#if DEBUG
+	n_check_ticks++;
+#endif
+
+	uint64 now;
+	static uint64 next = 0;
+	if (next == 0)
+		next = emulated_ticks_start = GetTicks_usec();
+
+	// Update total instructions count
+	if (emulated_ticks <= 0) {
+		emulated_ticks_current += (emulated_ticks_quantum - emulated_ticks);
+		// XXX: can you really have a machine fast enough to overflow
+		// a 63-bit m68k instruction counter within 16 ms?
+		if (emulated_ticks_current < 0) {
+			printf("WARNING: Overflowed 63-bit m68k instruction counter in less than 16 ms!\n");
+			goto recalibrate_quantum;
+		}
+	}
+
+	// Check for interrupt opportunity
+	now = GetTicks_usec();
+	if (next < now) {
+		one_tick();
+		do {
+			next += 16625;
+		} while (next < now);
+		emulated_ticks_count++;
+
+		// Recalibrate 1000 Hz quantum every 10 ticks
+		static uint64 last = 0;
+		if (last == 0)
+			last = now;
+		else if (now - last > 166250) {
+		  recalibrate_quantum:
+			emulated_ticks_quantum = ((uint64)emulated_ticks_current * 1000) / (now - last);
+			emulated_ticks_current = 0;
+			last = now;
+		}
+	}
+
+	// Update countdown
+	if (emulated_ticks <= 0)
+		emulated_ticks += emulated_ticks_quantum;
+}
+#endif
+
+
 /*
  *  Main program
  */
@@ -652,6 +714,7 @@ int main(int argc, char **argv)
 	sigaction(SIGINT, &sigint_sa, NULL);
 #endif
 
+#ifndef USE_CPU_EMUL_SERVICES
 #if defined(HAVE_PTHREADS)
 
 	// POSIX threads available, start 60Hz thread
@@ -715,8 +778,9 @@ int main(int argc, char **argv)
 	setitimer(ITIMER_REAL, &req, NULL);
 
 #endif
+#endif
 
-#ifdef HAVE_PTHREADS
+#ifdef USE_PTHREADS_SERVICES
 	// Start XPRAM watchdog thread
 	memcpy(last_xpram, XPRAM, XPRAM_SIZE);
 	xpram_thread_active = (pthread_create(&xpram_thread, NULL, xpram_func, NULL) == 0);
@@ -745,7 +809,13 @@ void QuitEmulator(void)
 	Exit680x0();
 #endif
 
-#if defined(HAVE_PTHREADS)
+#if defined(USE_CPU_EMUL_SERVICES)
+	// Show statistics
+	uint64 emulated_ticks_end = GetTicks_usec();
+	D(bug("%ld ticks in %ld usec = %f ticks/sec [%ld tick checks]\n",
+		  (long)emulated_ticks_count, (long)(emulated_ticks_end - emulated_ticks_start),
+		  emulated_ticks_count * 1000000.0 / (emulated_ticks_end - emulated_ticks_start), (long)n_check_ticks));
+#elif defined(USE_PTHREADS_SERVICES)
 	// Stop 60Hz thread
 	if (tick_thread_active) {
 		tick_thread_cancel = true;
@@ -764,7 +834,7 @@ void QuitEmulator(void)
 	setitimer(ITIMER_REAL, &req, NULL);
 #endif
 
-#ifdef HAVE_PTHREADS
+#ifdef USE_PTHREADS_SERVICES
 	// Stop XPRAM watchdog thread
 	if (xpram_thread_active) {
 		xpram_thread_cancel = true;
@@ -1021,7 +1091,7 @@ static void xpram_watchdog(void)
 	}
 }
 
-#ifdef HAVE_PTHREADS
+#ifdef USE_PTHREADS_SERVICES
 static void *xpram_func(void *arg)
 {
 	while (!xpram_thread_cancel) {
@@ -1046,7 +1116,7 @@ static void one_second(void)
 	SetInterruptFlag(INTFLAG_1HZ);
 	TriggerInterrupt();
 
-#ifndef HAVE_PTHREADS
+#ifndef USE_PTHREADS_SERVICES
 	static int second_counter = 0;
 	if (++second_counter > 60) {
 		second_counter = 0;
@@ -1063,7 +1133,7 @@ static void one_tick(...)
 		one_second();
 	}
 
-#if !defined(HAVE_PTHREADS) && !defined(USE_SDL_VIDEO)
+#if !defined(USE_PTHREADS_SERVICES) && !defined(USE_SDL_VIDEO)
 	// No threads available, perform video refresh and networking from here
 	VideoRefresh();
 	SetInterruptFlag(INTFLAG_ETHER);
@@ -1076,7 +1146,7 @@ static void one_tick(...)
 	}
 }
 
-#ifdef HAVE_PTHREADS
+#ifdef USE_PTHREADS_SERVICES
 static void *tick_func(void *arg)
 {
 	uint64 start = GetTicks_usec();
diff --git a/BasiliskII/src/Unix/sysdeps.h b/BasiliskII/src/Unix/sysdeps.h
index 46a39b0a..3b4a0c42 100644
--- a/BasiliskII/src/Unix/sysdeps.h
+++ b/BasiliskII/src/Unix/sysdeps.h
@@ -110,6 +110,19 @@
 /* BSD socket API supported */
 #define SUPPORTS_UDP_TUNNEL 1
 
+/* Use the CPU emulator to check for periodic tasks? */
+#ifdef HAVE_PTHREADS
+#define USE_PTHREADS_SERVICES
+#endif
+#if EMULATED_68K
+#if defined(__NetBSD__)
+#define USE_CPU_EMUL_SERVICES
+#endif
+#endif
+#ifdef USE_CPU_EMUL_SERVICES
+#undef USE_PTHREADS_SERVICES
+#endif
+
 
 /* Data types */
 typedef unsigned char uint8;
diff --git a/BasiliskII/src/Unix/video_x.cpp b/BasiliskII/src/Unix/video_x.cpp
index 238fdc07..dc53df1e 100644
--- a/BasiliskII/src/Unix/video_x.cpp
+++ b/BasiliskII/src/Unix/video_x.cpp
@@ -1549,7 +1549,7 @@ bool X11_monitor_desc::video_open(void)
 	LOCK_FRAME_BUFFER;
 
 	// Start redraw/input thread
-#ifdef HAVE_PTHREADS
+#ifdef USE_PTHREADS_SERVICES
 	redraw_thread_cancel = false;
 	Set_pthread_attr(&redraw_thread_attr, 0);
 	redraw_thread_active = (pthread_create(&redraw_thread, &redraw_thread_attr, redraw_func, NULL) == 0);
@@ -1745,7 +1745,7 @@ void X11_monitor_desc::video_close(void)
 	D(bug("video_close()\n"));
 
 	// Stop redraw thread
-#ifdef HAVE_PTHREADS
+#ifdef USE_PTHREADS_SERVICES
 	if (redraw_thread_active) {
 		redraw_thread_cancel = true;
 		redraw_thread_cancel_ack = false;
@@ -2596,7 +2596,7 @@ void VideoRefresh(void)
 const int VIDEO_REFRESH_HZ = 60;
 const int VIDEO_REFRESH_DELAY = 1000000 / VIDEO_REFRESH_HZ;
 
-#ifdef HAVE_PTHREADS
+#ifdef USE_PTHREADS_SERVICES
 static void *redraw_func(void *arg)
 {
 	int fd = ConnectionNumber(x_display);
diff --git a/BasiliskII/src/uae_cpu/compiler/compemu_support.cpp b/BasiliskII/src/uae_cpu/compiler/compemu_support.cpp
index ad377a46..25a5ddec 100644
--- a/BasiliskII/src/uae_cpu/compiler/compemu_support.cpp
+++ b/BasiliskII/src/uae_cpu/compiler/compemu_support.cpp
@@ -6727,6 +6727,15 @@ static void compile_block(cpu_history* pc_hist, int blocklen)
 	    init_comp();
 	    was_comp=1;
 
+#ifdef USE_CPU_EMUL_SERVICES
+	    raw_sub_l_mi((uintptr)&emulated_ticks,blocklen);
+	    raw_jcc_b_oponly(NATIVE_CC_GT);
+	    uae_s8 *branchadd=(uae_s8*)get_target();
+	    emit_byte(0);
+	    raw_call((uintptr)cpu_do_check_ticks);
+	    *branchadd=(uintptr)get_target()-((uintptr)branchadd+1);
+#endif
+
 #if JIT_DEBUG
 		if (JITDebug) {
 			raw_mov_l_mi((uintptr)&last_regs_pc_p,(uintptr)pc_hist[0].location);
@@ -7037,6 +7046,9 @@ static void compile_block(cpu_history* pc_hist, int blocklen)
 	compile_time += (clock() - start_time);
 #endif
     }
+
+    /* Account for compilation time */
+    cpu_do_check_ticks();
 }
 
 void do_nothing(void)
@@ -7052,6 +7064,7 @@ void exec_nostats(void)
 		m68k_record_step(m68k_getpc());
 #endif
 		(*cpufunctbl[opcode])(opcode);
+		cpu_check_ticks();
 		if (end_block(opcode) || SPCFLAGS_TEST(SPCFLAG_ALL)) {
 			return; /* We will deal with the spcflags in the caller */
 		}
@@ -7077,6 +7090,7 @@ void execute_normal(void)
 			m68k_record_step(m68k_getpc());
 #endif
 			(*cpufunctbl[opcode])(opcode);
+			cpu_check_ticks();
 			if (end_block(opcode) || SPCFLAGS_TEST(SPCFLAG_ALL) || blocklen>=MAXRUN) {
 				compile_block(pc_hist, blocklen);
 				return; /* We will deal with the spcflags in the caller */
diff --git a/BasiliskII/src/uae_cpu/newcpu.cpp b/BasiliskII/src/uae_cpu/newcpu.cpp
index 9122a99d..a82f2c87 100644
--- a/BasiliskII/src/uae_cpu/newcpu.cpp
+++ b/BasiliskII/src/uae_cpu/newcpu.cpp
@@ -1349,6 +1349,7 @@ void m68k_do_execute (void)
 		m68k_record_step(m68k_getpc());
 #endif
 		(*cpufunctbl[opcode])(opcode);
+		cpu_check_ticks();
 		if (SPCFLAGS_TEST(SPCFLAG_ALL_BUT_EXEC_RETURN)) {
 			if (m68k_do_specialties())
 				return;
diff --git a/BasiliskII/src/uae_cpu/newcpu.h b/BasiliskII/src/uae_cpu/newcpu.h
index f3c47e6d..24518c16 100644
--- a/BasiliskII/src/uae_cpu/newcpu.h
+++ b/BasiliskII/src/uae_cpu/newcpu.h
@@ -295,5 +295,18 @@ extern void m68k_do_compile_execute(void);
 extern void m68k_compile_execute(void);
 #endif
 #endif
+#ifdef USE_CPU_EMUL_SERVICES
+extern int32 emulated_ticks;
+extern void cpu_do_check_ticks(void);
+
+static inline void cpu_check_ticks(void)
+{
+	if (--emulated_ticks <= 0)
+		cpu_do_check_ticks();
+}
+#else
+#define cpu_check_ticks()
+#define cpu_do_check_ticks()
+#endif
  
 #endif /* NEWCPU_H */