diff --git a/src/mess/machine/hp48.c b/src/mess/machine/hp48.c
index 0980d5cae50..012d71f367c 100644
--- a/src/mess/machine/hp48.c
+++ b/src/mess/machine/hp48.c
@@ -160,8 +160,8 @@ static void hp48_rs232_send_byte( running_machine &machine )
 	hp48_state *state = machine.driver_data<hp48_state>();
 	UINT8 data = HP48_IO_8(0x16); /* byte to send */
 
-	LOG_SERIAL(( "%05x %f hp48_rs232_send_byte: start sending, data=%02x\n",
-				machine.device("maincpu")->safe_pcbase(), machine.time().as_double(), data ));
+	LOG_SERIAL(( "%s %f hp48_rs232_send_byte: start sending, data=%02x\n",
+				machine.describe_context(), machine.time().as_double(), data ));
 
 	/* set byte sending and send buffer full */
 	state->m_io[0x12] |= 3;
@@ -237,8 +237,8 @@ static const chardev_interface hp48_chardev_iface =
 void hp48_reg_out( device_t *device, int out )
 {
 	hp48_state *state = device->machine().driver_data<hp48_state>();
-	LOG(( "%05x %f hp48_reg_out: %03x\n",
-			device->machine().device("maincpu")->safe_pcbase(), device->machine().time().as_double(), out ));
+	LOG(( "%s %f hp48_reg_out: %03x\n",
+			device->machine().describe_context(), device->machine().time().as_double(), out ));
 
 	/* bits 0-8: keyboard lines */
 	state->m_out = out & 0x1ff;
@@ -275,8 +275,8 @@ static int hp48_get_in( running_machine &machine )
 int hp48_reg_in( device_t *device )
 {
 	int in = hp48_get_in(device->machine());
-	LOG(( "%05x %f hp48_reg_in: %04x\n",
-			device->machine().device("maincpu")->safe_pcbase(), device->machine().time().as_double(), in ));
+	LOG(( "%s %f hp48_reg_in: %04x\n",
+			device->machine().describe_context(), device->machine().time().as_double(), in ));
 	return in;
 }
 
@@ -320,7 +320,7 @@ TIMER_CALLBACK_MEMBER(hp48_state::hp48_kbd_cb)
 void hp48_rsi( device_t *device )
 {
 	hp48_state *state = device->machine().driver_data<hp48_state>();
-	LOG(( "%05x %f hp48_rsi\n", device->machine().device("maincpu")->safe_pcbase(), device->machine().time().as_double() ));
+	LOG(( "%s %f hp48_rsi\n", device->machine().describe_context(), device->machine().time().as_double() ));
 
 	/* enables interrupts on key repeat
 	   (normally, there is only one interrupt, when the key is pressed)
@@ -362,8 +362,8 @@ void hp48_state::hp48_update_annunciators()
 
 WRITE8_MEMBER(hp48_state::hp48_io_w)
 {
-	LOG(( "%05x %f hp48_io_w: off=%02x data=%x\n",
-			space.device().safe_pcbase(), space.machine().time().as_double(), offset, data ));
+	LOG(( "%s %f hp48_io_w: off=%02x data=%x\n",
+			space.machine().describe_context(), space.machine().time().as_double(), offset, data ));
 
 	switch( offset )
 	{
@@ -405,7 +405,7 @@ WRITE8_MEMBER(hp48_state::hp48_io_w)
 
 	/* cards */
 	case 0x0e:
-		LOG(( "%05x: card control write %02x\n", space.device().safe_pcbase(), data ));
+		LOG(( "%s: card control write %02x\n", space.machine().describe_context(), data ));
 
 		/* bit 0: software interrupt */
 		if ( data & 1 )
@@ -424,7 +424,7 @@ WRITE8_MEMBER(hp48_state::hp48_io_w)
 		break;
 
 	case 0x0f:
-		LOG(( "%05x: card info write %02x\n", space.device().safe_pcbase(), data ));
+		LOG(( "%s: card info write %02x\n", space.machine().describe_context(), data ));
 		m_io[0x0f] = data;
 		break;
 
@@ -554,7 +554,7 @@ READ8_MEMBER(hp48_state::hp48_io_r)
 	/* cards */
 	case 0x0e: /* detection */
 		data = m_io[0x0e];
-		LOG(( "%05x: card control read %02x\n", space.device().safe_pcbase(), data ));
+		LOG(( "%s: card control read %02x\n", space.machine().describe_context(), data ));
 		break;
 	case 0x0f: /* card info */
 		data = 0;
@@ -572,15 +572,15 @@ READ8_MEMBER(hp48_state::hp48_io_r)
 			if ( m_port_size[0] && m_port_write[0] ) data |= 4;
 			if ( m_port_size[1] && m_port_write[1] ) data |= 8;
 		}
-		LOG(( "%05x: card info read %02x\n", space.device().safe_pcbase(), data ));
+		LOG(( "%s: card info read %02x\n", space.machine().describe_context(), data ));
 		break;
 
 
 	default: data = m_io[offset];
 	}
 
-	LOG(( "%05x %f hp48_io_r: off=%02x data=%x\n",
-			space.device().safe_pcbase(), space.machine().time().as_double(), offset, data ));
+	LOG(( "%s %f hp48_io_r: off=%02x data=%x\n",
+			space.machine().describe_context(), space.machine().time().as_double(), offset, data ));
 	return data;
 }
 
@@ -593,7 +593,7 @@ READ8_MEMBER(hp48_state::hp48_bank_r)
 	offset &= 0x7e;
 	if ( m_bank_switch != offset )
 	{
-		LOG(( "%05x %f hp48_bank_r: off=%03x\n", space.device().safe_pcbase(), space.machine().time().as_double(), offset ));
+		LOG(( "%s %f hp48_bank_r: off=%03x\n", space.machine().describe_context(), space.machine().time().as_double(), offset ));
 		m_bank_switch = offset;
 		hp48_apply_modules();
 	}
@@ -823,7 +823,7 @@ static void hp48_reset_modules( running_machine &machine )
 /* RESET opcode */
 void hp48_mem_reset( device_t *device )
 {
-	LOG(( "%05x %f hp48_mem_reset\n", device->machine().device("maincpu")->safe_pcbase(), device->machine().time().as_double() ));
+	LOG(( "%s %f hp48_mem_reset\n", device->machine().describe_context(), device->machine().time().as_double() ));
 	hp48_reset_modules(device->machine());
 }
 
@@ -834,7 +834,7 @@ void hp48_mem_config( device_t *device, int v )
 	hp48_state *state = device->machine().driver_data<hp48_state>();
 	int i;
 
-	LOG(( "%05x %f hp48_mem_config: %05x\n", device->machine().device("maincpu")->safe_pcbase(), device->machine().time().as_double(), v ));
+	LOG(( "%s %f hp48_mem_config: %05x\n", device->machine().describe_context(), device->machine().time().as_double(), v ));
 
 	/* find the highest priority unconfigured module (except non-configurable NCE1)... */
 	for ( i = 0; i < 5; i++ )
@@ -866,7 +866,7 @@ void hp48_mem_unconfig( device_t *device, int v )
 {
 	hp48_state *state = device->machine().driver_data<hp48_state>();
 	int i;
-	LOG(( "%05x %f hp48_mem_unconfig: %05x\n", device->machine().device("maincpu")->safe_pcbase(), device->machine().time().as_double(), v ));
+	LOG(( "%s %f hp48_mem_unconfig: %05x\n", device->machine().describe_context(), device->machine().time().as_double(), v ));
 
 	/* find the highest priority fully configured module at address v (except NCE1)... */
 	for ( i = 0; i < 5; i++ )
@@ -909,8 +909,8 @@ int  hp48_mem_id( device_t *device )
 		}
 	}
 
-	LOG(( "%05x %f hp48_mem_id = %02x\n",
-			device->machine().device("maincpu")->safe_pcbase(), device->machine().time().as_double(), data ));
+	LOG(( "%s %f hp48_mem_id = %02x\n",
+			device->machine().describe_context(), device->machine().time().as_double(), data ));
 
 	return data; /* everything is configured */
 }
diff --git a/src/mess/machine/thomson.c b/src/mess/machine/thomson.c
index 312bca1d5e4..db2d65a0e11 100644
--- a/src/mess/machine/thomson.c
+++ b/src/mess/machine/thomson.c
@@ -684,7 +684,7 @@ WRITE8_MEMBER( to7_io_line_device::porta_out )
 	int tx  = data & 1;
 	int dtr = ( data & 2 ) ? 1 : 0;
 
-	LOG_IO(( "$%04x %f to7_io_porta_out: tx=%i, dtr=%i\n",  machine().device("maincpu")->safe_pcbase(), machine().time().as_double(), tx, dtr ));
+	LOG_IO(( "%s %f to7_io_porta_out: tx=%i, dtr=%i\n",  machine().describe_context(), machine().time().as_double(), tx, dtr ));
 	if ( dtr )
 		m_connection_state |=  SERIAL_STATE_DTR;
 	else
@@ -708,7 +708,7 @@ READ8_MEMBER( to7_io_line_device::porta_in )
 	else
 		cts = !printer->busy_r();
 
-	LOG_IO(( "$%04x %f to7_io_porta_in: mode=%i cts=%i, dsr=%i, rd=%i\n", machine().device("maincpu")->safe_pcbase(), machine().time().as_double(), machine().driver_data<thomson_state>()->to7_io_mode(), cts, dsr, rd ));
+	LOG_IO(( "%s %f to7_io_porta_in: mode=%i cts=%i, dsr=%i, rd=%i\n", machine().describe_context(), machine().time().as_double(), machine().driver_data<thomson_state>()->to7_io_mode(), cts, dsr, rd ));
 
 	return (dsr ? 0x20 : 0) | (cts ? 0x40 : 0) | (rd ? 0x80: 0);
 }
@@ -1204,8 +1204,8 @@ READ8_HANDLER ( to7_midi_r )
 		/* bit 5:     overrun */
 		/* bit 6:     parity error (ignored) */
 		/* bit 7:     interrupt */
-		LOG_MIDI(( "$%04x %f to7_midi_r: status $%02X (rdrf=%i, tdre=%i, ovrn=%i, irq=%i)\n",
-				space.machine().device("maincpu")->safe_pcbase(), space.machine().time().as_double(), to7_midi_status,
+		LOG_MIDI(( "%s %f to7_midi_r: status $%02X (rdrf=%i, tdre=%i, ovrn=%i, irq=%i)\n",
+				space.machine().describe_context(), space.machine().time().as_double(), to7_midi_status,
 				(to7_midi_status & ACIA_6850_RDRF) ? 1 : 0,
 				(to7_midi_status & ACIA_6850_TDRE) ? 1 : 0,
 				(to7_midi_status & ACIA_6850_OVRN) ? 1 : 0,
@@ -1224,8 +1224,8 @@ READ8_HANDLER ( to7_midi_r )
 						else
 								to7_midi_status &= ~ACIA_6850_OVRN;
 						to7_midi_overrun = 0;
-						LOG_MIDI(( "$%04x %f to7_midi_r: read data $%02X\n",
-									space.machine().device("maincpu")->safe_pcbase(), space.machine().time().as_double(), data ));
+						LOG_MIDI(( "%s %f to7_midi_r: read data $%02X\n",
+									space.machine().describe_context(), space.machine().time().as_double(), data ));
 						to7_midi_update_irq( space.machine() );
 				}
 				return data;
@@ -1233,8 +1233,8 @@ READ8_HANDLER ( to7_midi_r )
 
 
 	default:
-		logerror( "$%04x to7_midi_r: invalid offset %i\n",
-				space.machine().device("maincpu")->safe_pcbase(),  offset );
+		logerror( "%s to7_midi_r: invalid offset %i\n",
+				space.machine().describe_context(),  offset );
 		return 0;
 	}
 }
@@ -1252,7 +1252,7 @@ WRITE8_HANDLER ( to7_midi_w )
 		if ( (data & 3) == 3 )
 		{
 			/* reset */
-			LOG_MIDI(( "$%04x %f to7_midi_w: reset (data=$%02X)\n", space.machine().device("maincpu")->safe_pcbase(), space.machine().time().as_double(), data ));
+			LOG_MIDI(( "%s %f to7_midi_w: reset (data=$%02X)\n", space.machine().describe_context(), space.machine().time().as_double(), data ));
 			to7_midi_overrun = 0;
 			to7_midi_status = 2;
 			to7_midi_intr = 0;
@@ -1268,8 +1268,8 @@ WRITE8_HANDLER ( to7_midi_w )
 				static const int bits[8] = { 7,7,7,7,8,8,8,8 };
 				static const int stop[8] = { 2,2,1,1,2,1,1,1 };
 				static const char parity[8] = { 'e','o','e','o','-','-','e','o' };
-				LOG_MIDI(( "$%04x %f to7_midi_w: set control to $%02X (bits=%i, stop=%i, parity=%c, intr in=%i out=%i)\n",
-						space.machine().device("maincpu")->safe_pcbase(), space.machine().time().as_double(),
+				LOG_MIDI(( "%s %f to7_midi_w: set control to $%02X (bits=%i, stop=%i, parity=%c, intr in=%i out=%i)\n",
+						space.machine().describe_context(), space.machine().time().as_double(),
 						data,
 						bits[ (data >> 2) & 7 ],
 						stop[ (data >> 2) & 7 ],
@@ -1283,7 +1283,7 @@ WRITE8_HANDLER ( to7_midi_w )
 
 
 	case 1: /* output data */
-		LOG_MIDI(( "$%04x %f to7_midi_w: write data $%02X\n", space.machine().device("maincpu")->safe_pcbase(), space.machine().time().as_double(), data ));
+		LOG_MIDI(( "%s %f to7_midi_w: write data $%02X\n", space.machine().describe_context(), space.machine().time().as_double(), data ));
 		if ( data == 0x55 )
 			/* cable-detect: shortcut */
 			chardev_fake_in( to7_midi_chardev, 0x55 );
@@ -1297,7 +1297,7 @@ WRITE8_HANDLER ( to7_midi_w )
 
 
 	default:
-		logerror( "$%04x to7_midi_w: invalid offset %i (data=$%02X) \n", space.machine().device("maincpu")->safe_pcbase(), offset, data );
+		logerror( "%s to7_midi_w: invalid offset %i (data=$%02X) \n", space.machine().describe_context(), offset, data );
 	}
 }