diff --git a/csr.c b/csr.c
index dd11cc1..99adcee 100644
--- a/csr.c
+++ b/csr.c
@@ -129,7 +129,7 @@ int csr_try_mbus_held(csr_t *csr) {
 	return 1;
 }
 
-void csr_set_access_error(csr_t *csr, int cpu, int type) {
+void csr_set_access_error(csr_t *csr, int cpu, int type, int addr, int is_write) {
 	int v=0;
 	if (cpu==0) {
 		if (type&ACCESS_ERROR_U) v|=ERR_UBE_DMA;
@@ -138,10 +138,18 @@ void csr_set_access_error(csr_t *csr, int cpu, int type) {
 		if (type&ACCESS_ERROR_U) v|=ERR_UBE_JOB;
 		if (type&ACCESS_ERROR_A) v|=ERR_ABE_JOB;
 	}
-	if (type&ACCESS_ERROR_MBTO) v|=ERR_MBTO;
+	if (type&ACCESS_ERROR_MBTO) {
+		v|=ERR_MBTO;
+		if (emu_get_mb_diag()) {
+			emu_raise_int(INT_VECT_MB_IF_ERR, INT_LEVEL_MB_IF_ERR, 1);
+			csr->reg[CSR_I_MBERR/2]=(addr>>11)&0xfe;
+			if (!is_write) csr->reg[CSR_I_MBERR/2]|=0x1;
+		}
+	}
 	csr->reg[CSR_I_ERR/2]|=v;
 }
 
+
 void csr_set_parity_error(csr_t *c, int hl) {
 	c->reg[CSR_I_PERR1/2]&=~((1<<12)|(1<<13));
 	if (hl&2) c->reg[CSR_I_PERR1/2]|=(1<<12);
@@ -165,6 +173,8 @@ void csr_write16(void *obj, unsigned int a, unsigned int val) {
 		emu_enable_mapper(!(val&MISC_ENMAP));
 		if ((val&MISC_HOLDMBUS)==0) {
 			val&=~MISC_TBUSY;
+		} else {
+			val|=MISC_TBUSY;
 		}
 		int v=0;
 		if ((val&MISC_SCSIDL)==0) v|=SCSI_DIAG_LATCH;
@@ -177,6 +187,7 @@ void csr_write16(void *obj, unsigned int a, unsigned int val) {
 		v=0;
 		if (val&MISC_DIAGPL) v|=1;
 		if (val&MISC_DIAGPH) v|=2;
+
 		emu_set_force_parity_error(v);
 		emu_set_mb_diag(val&MISC_DIAGMB);
 	} else if (a==CSR_O_KILL) { //kill
@@ -299,12 +310,9 @@ void csr_write16_mmio(void *obj, unsigned int a, unsigned int val) {
 	}
 }
 
-void csr_raise_error(csr_t *c, int error, unsigned int addr) {
-	if (error==CSR_ERR_MBUS) {
-		emu_raise_int(INT_VECT_MB_IF_ERR, INT_LEVEL_MB_IF_ERR, 1);
-		c->reg[CSR_I_MBERR/2]=(addr>>11)&0xfe;
-		if (addr&EMU_MBUS_ERROR_READ) c->reg[CSR_I_MBERR/2]|=0x1;
-	}
+unsigned int csr_read16_mmio(void *obj, unsigned int a) {
+	csr_write16_mmio(obj, a, 0);
+	return 0;
 }
 
 
diff --git a/csr.h b/csr.h
index 188b7ac..58f4be1 100644
--- a/csr.h
+++ b/csr.h
@@ -9,21 +9,18 @@ void csr_write8(void *obj, unsigned int a, unsigned int val);
 void csr_write16(void *obj, unsigned int a, unsigned int val);
 void csr_write32(void *obj, unsigned int a, unsigned int val);
 void csr_write16_mmio(void *obj, unsigned int a, unsigned int val);
+unsigned int csr_read16_mmio(void *obj, unsigned int a);
 csr_t *csr_new(scsi_t *scsi);
 
 int csr_cpu_is_reset(csr_t *csr, int cpu);
 int csr_get_rtc_int_ena(csr_t *csr, int cpu);
 int csr_try_mbus_held(csr_t *csr);
 
-
-#define CSR_ERR_MBUS 1
-void csr_raise_error(csr_t *c, int error, unsigned int addr);
-
 #define ACCESS_ERROR_OK 0
 #define ACCESS_ERROR_U 1
 #define ACCESS_ERROR_A 2
 #define ACCESS_ERROR_MBTO 3
-void csr_set_access_error(csr_t *csr, int cpu, int type);
+void csr_set_access_error(csr_t *csr, int cpu, int type, int addr, int is_write);
 
 
 void csr_set_parity_error(csr_t *c, int hl);
\ No newline at end of file
diff --git a/emu.c b/emu.c
index 25d184c..7edd228 100644
--- a/emu.c
+++ b/emu.c
@@ -174,7 +174,7 @@ static int check_can_access(mem_range_t *m, unsigned int address) {
 		ret=0;
 	}
 	if (!ret) {
-		csr_set_access_error(csr, cur_cpu, ACCESS_ERROR_A);
+		csr_set_access_error(csr, cur_cpu, ACCESS_ERROR_A, address, 0);
 		m68k_pulse_bus_error();
 	}
 	return ret;
@@ -307,17 +307,17 @@ void emu_set_cur_mapid(uint8_t id) {
 //thing to actually throw the error.
 
 static int check_mem_access(unsigned int address, int flags) {
-	static int recursive_error=0;
 	if (!mapper_enabled) return 1;
 	if ((fc_bits&3)==2) flags=ACCESS_X;
 	if (fc_bits&4) flags|=ACCESS_SYSTEM;
 	int access=mapper_access_allowed(mapper, address, flags);
 	if (access!=ACCESS_ERROR_OK) {
-		EMU_LOG_DEBUG("Bus error! Access %x\n", address);
-//		if (address==0x1000) do_tracefile=1;
-		dump_cpu_state();
-		dump_callstack();
-		csr_set_access_error(csr, cur_cpu, access);
+		if (log_level_active(LOG_SRC_MAPPER, LOG_DEBUG)) {
+			EMU_LOG_INFO("Illegal access! Access %x\n", address);
+			dump_cpu_state();
+			dump_callstack();
+		}
+		csr_set_access_error(csr, cur_cpu, access, address, flags&ACCESS_W);
 
 		//note THIS WILL NOT RETURN!
 		//(m68ki_exception_bus_error ends with a longjmp)
@@ -455,13 +455,9 @@ int emu_write_byte(int addr, int val) {
 }
 
 void emu_mbus_error(unsigned int addr) {
-	mem_range_t *r=find_range_by_name("CSR");
-	if (addr&EMU_MBUS_ERROR_TIMEOUT) {
-		csr_set_access_error(csr, 1, ACCESS_ERROR_MBTO);
+	csr_set_access_error(csr, 1, ACCESS_ERROR_MBTO, addr&0xffffff, !(addr&EMU_MBUS_ERROR_READ));
+	if (addr&EMU_MBUS_BUSERROR) {
 		emu_bus_error();
-	} else {
-		csr_t *c=(csr_t*)r->obj;
-		csr_raise_error(c, CSR_ERR_MBUS, addr);
 	}
 }
 
@@ -537,6 +533,7 @@ csr_t *setup_csr(const char *name, const char *mmio_name, const char *scsi_name)
 	m->read16=csr_read16;
 	m->read8=csr_read8;
 	mm->write16=csr_write16_mmio;
+	mm->read16=csr_read16_mmio;
 	return r;
 }
 
@@ -604,9 +601,7 @@ void setup_mbus(const char *name, const char *ioname) {
 
 //1 if held
 int emu_try_mbus_held() {
-	mem_range_t *r=find_range_by_name("CSR");
-	csr_t *c=(csr_t*)r->obj;
-	return csr_try_mbus_held(c);
+	return csr_try_mbus_held(csr);
 }
 
 void setup_nop(const char *name) {
diff --git a/emu.h b/emu.h
index cfea314..24bb3de 100644
--- a/emu.h
+++ b/emu.h
@@ -35,5 +35,5 @@ void emu_start(emu_cfg_t *cfg);
 void emu_schedule_int_us(int us);
 
 #define EMU_MBUS_ERROR_READ 0x80000000
-#define EMU_MBUS_ERROR_TIMEOUT 0x40000000
+#define EMU_MBUS_BUSERROR 0x40000000
 void emu_mbus_error(unsigned int addr);
diff --git a/log.c b/log.c
index ee57e6c..0e76221 100644
--- a/log.c
+++ b/log.c
@@ -46,6 +46,10 @@ void log_set_level(enum log_source source, enum log_level msg_level) {
 	log_channel_verbose_level[source]=msg_level;
 }
 
+int log_level_active(enum log_source source, enum log_level msg_level) {
+	return log_channel_verbose_level[source] >= msg_level;
+}
+
 int log_printf(enum log_source source, enum log_level msg_level, const char *format, ...) {
 	static_assert(sizeof(log_channel_verbose_level)/sizeof(log_channel_verbose_level[0])==LOG_SRC_MAX, 
 				"log_channel_verbose_level missing an entry");
diff --git a/log.h b/log.h
index 8024edf..e1af0ee 100644
--- a/log.h
+++ b/log.h
@@ -28,5 +28,6 @@ enum log_level {
 
 void log_set_level(enum log_source source, enum log_level msg_level);
 int log_printf(enum log_source source, enum log_level msg_level, const char *format, ...);
+int log_level_active(enum log_source source, enum log_level msg_level);
 
 #endif
diff --git a/mapper.c b/mapper.c
index d5a0432..056c37b 100644
--- a/mapper.c
+++ b/mapper.c
@@ -94,7 +94,7 @@ int mapper_access_allowed(mapper_t *m, unsigned int a, int access_flags) {
 	assert(p<=2048 && "out of range addr");
 	if (access_flags&ACCESS_SYSTEM) p+=2048;
 	int r=access_allowed_page(m, p, access_flags);
-	if (r) {
+	if (r && log_level_active(LOG_SRC_MAPPER, LOG_DEBUG)) {
 		MAPPER_LOG_DEBUG("Mapper: Access fault at addr %x page %d. CPU state:\n", a, p);
 		dump_cpu_state();
 		dump_callstack();
diff --git a/mbus.c b/mbus.c
index 4f3135a..9c89df5 100644
--- a/mbus.c
+++ b/mbus.c
@@ -21,54 +21,37 @@ but they obvs can't do that for 8-bit writes/reads. So 16-bit writes go through
 transparently, but a write/read to 8-bit address x happens to x^1 :X
 */
 
-
-
-
 static int mbus_held() {
 	if (!emu_try_mbus_held()) return 0;
 	MBUS_LOG_DEBUG("Blocking op: bus held\n");
 	return 1;
 }
 
-static int on_wrong_cpu(int addr) {
-	int r=emu_get_cur_cpu();
-	if (r==1) return 0;
-	MBUS_LOG_NOTICE("Mbus access to %x from wrong CPU\n", addr);
-	emu_bus_error();
-	return 1;
-}
-
-
-
 void mbus_write8(void *obj, unsigned int a, unsigned int val) {
-	if (on_wrong_cpu(a)) return;
 	MBUS_LOG_DEBUG("MBUS: wb %x->%x %x\n", a, a+0x780000, val);
 	if (mbus_held()) {
 		MBUS_LOG_NOTICE("MBUS: ^^ write held.\n");
 		return;
 	}
 	if (!emu_get_mb_diag()){
-//		emu_mbus_error(a|EMU_MBUS_ERROR_TIMEOUT);
 		return;
 	}
 	int r=emu_write_byte((a+0x780000)^1, val);
-	if (!r) emu_mbus_error(a);
+	if (r==-1) emu_mbus_error(a);
 }
 
 void mbus_write16(void *obj, unsigned int a, unsigned int val) {
-	if (on_wrong_cpu(a)) return;
 	MBUS_LOG_DEBUG("MBUS: ww %x->%x %x\n", a, a+0x780000, val);
 	if (mbus_held()) {
 		MBUS_LOG_NOTICE("MBUS: ^^ write held.\n");
 		return;
 	}
 	if (!emu_get_mb_diag()){
-//		emu_mbus_error(a|EMU_MBUS_ERROR_TIMEOUT);
 		return;
 	}
 	int r=emu_write_byte((a+0x780000), val>>8);
-	r&=emu_write_byte((a+0x780001), val);
-	if (!r) emu_mbus_error(a);
+	r+=emu_write_byte((a+0x780001), val);
+	if (r<0) emu_mbus_error(a);
 }
 
 void mbus_write32(void *obj, unsigned int a, unsigned int val) {
@@ -77,21 +60,18 @@ void mbus_write32(void *obj, unsigned int a, unsigned int val) {
 }
 
 unsigned int mbus_read8(void *obj, unsigned int a) {
-	if (on_wrong_cpu(a)) return 0;
 	MBUS_LOG_DEBUG("MBUS: rb %x->%x\n", a, a+0x780000);
+	if (!emu_get_mb_diag()) return 0;
 	//Mbus in diag modes errors with a MBTO.
-	emu_mbus_error(a|EMU_MBUS_ERROR_TIMEOUT);
+	emu_mbus_error(a|EMU_MBUS_BUSERROR);
 	return 0;
 }
 
 unsigned int mbus_read16(void *obj, unsigned int a) {
-	if (on_wrong_cpu(a)) return 0;
 	MBUS_LOG_DEBUG("MBUS: rw %x->%x\n", a, a+0x780000);
-	if (!emu_get_mb_diag()){
-		return 0;
-	}
+	if (!emu_get_mb_diag()) return 0;
 	//Mbus in diag modes errors with a MBTO.
-	emu_mbus_error(a|EMU_MBUS_ERROR_TIMEOUT);
+	emu_mbus_error(a|EMU_MBUS_BUSERROR);
 	return 0;
 }
 
@@ -101,13 +81,14 @@ unsigned int mbus_read32(void *obj, unsigned int a) {
 
 void mbus_io_write(void *obj, unsigned int a, unsigned int val) {
 	if (emu_get_mb_diag()) return;
-//	printf("mbio wr %x\n", a);
-	emu_mbus_error(a|EMU_MBUS_ERROR_TIMEOUT);
+	MBUS_LOG_DEBUG("mbio wr %x\n", a);
+	emu_mbus_error(a|EMU_MBUS_BUSERROR);
 }
 
 unsigned int mbus_io_read(void *obj, unsigned int a) {
 	if (emu_get_mb_diag()) return 0;
-	emu_mbus_error(a|EMU_MBUS_ERROR_TIMEOUT);
+	MBUS_LOG_DEBUG("mbio rd %x\n", a);
+	emu_mbus_error(a|EMU_MBUS_ERROR_READ|EMU_MBUS_BUSERROR);
 	return 0;
 }
 
diff --git a/rtc.c b/rtc.c
index 942dd3f..6804de3 100644
--- a/rtc.c
+++ b/rtc.c
@@ -111,7 +111,8 @@ void rtc_write8(void *obj, unsigned int a, unsigned int val) {
 	}
 	handle_irq(r);
 	if (a!=CALREGC && a!=CALREGD) r->reg[a]=val;
-	rtc_sanitize_vals(r);
+	//Sanitize values if clock is running
+	if (!(r->reg[CALREGB]&0x80)) rtc_sanitize_vals(r);
 }
 
 void rtc_write16(void *obj, unsigned int a, unsigned int val) {