diff --git a/src/devices/machine/gen_latch.h b/src/devices/machine/gen_latch.h
index f00a16a083a..c0bee635b27 100644
--- a/src/devices/machine/gen_latch.h
+++ b/src/devices/machine/gen_latch.h
@@ -46,10 +46,6 @@ DECLARE_DEVICE_TYPE(GENERIC_LATCH_16, generic_latch_16_device)
 
 class generic_latch_base_device : public device_t
 {
-protected:
-	// construction/destruction
-	generic_latch_base_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock);
-
 public:
 	// configuration
 	template <class Object> devcb_base &set_data_pending_callback(Object &&cb) { return m_data_pending_cb.set_callback(std::forward<Object>(cb)); }
@@ -58,6 +54,9 @@ public:
 	DECLARE_READ_LINE_MEMBER(pending_r);
 
 protected:
+	// construction/destruction
+	generic_latch_base_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock);
+
 	virtual void device_start() override;
 	virtual void device_reset() override;
 
@@ -80,7 +79,7 @@ class generic_latch_8_device : public generic_latch_base_device
 {
 public:
 	// construction/destruction
-	generic_latch_8_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock);
+	generic_latch_8_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock = 0);
 
 	DECLARE_READ8_MEMBER( read );
 	DECLARE_WRITE8_MEMBER( write );
@@ -111,7 +110,7 @@ class generic_latch_16_device : public generic_latch_base_device
 {
 public:
 	// construction/destruction
-	generic_latch_16_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock);
+	generic_latch_16_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock = 0);
 
 	DECLARE_READ16_MEMBER( read );
 	DECLARE_WRITE16_MEMBER( write );
@@ -132,5 +131,4 @@ private:
 	u16 m_latched_value;
 };
 
-
 #endif  // MAME_MACHINE_GEN_LATCH_H
diff --git a/src/mame/drivers/bw2.cpp b/src/mame/drivers/bw2.cpp
index 8e1d67918ed..f0021d272fe 100644
--- a/src/mame/drivers/bw2.cpp
+++ b/src/mame/drivers/bw2.cpp
@@ -80,44 +80,28 @@ READ8_MEMBER( bw2_state::read )
 	if (offset < 0x8000)
 	{
 		if (!rom)
-		{
 			data = m_rom->base()[offset & 0x3fff];
-		}
 
 		if (!vram)
-		{
 			data = m_video_ram[offset & 0x3fff];
-		}
 
 		if (!ram1)
-		{
 			data = m_ram->pointer()[offset];
-		}
 
 		if (!ram2 && HAS_KB_OF_RAM(96))
-		{
 			data = m_ram->pointer()[0x10000 | offset];
-		}
 
 		if (!ram3 && HAS_KB_OF_RAM(128))
-		{
 			data = m_ram->pointer()[0x18000 | offset];
-		}
 
 		if (!ram4 && HAS_KB_OF_RAM(160))
-		{
 			data = m_ram->pointer()[0x20000 | offset];
-		}
 
 		if (!ram5 && HAS_KB_OF_RAM(192))
-		{
 			data = m_ram->pointer()[0x28000 | offset];
-		}
 
 		if (!ram6 && HAS_KB_OF_RAM(224))
-		{
 			data = m_ram->pointer()[0x30000 | offset];
-		}
 	}
 	else
 	{
@@ -150,39 +134,25 @@ WRITE8_MEMBER( bw2_state::write )
 	if (offset < 0x8000)
 	{
 		if (!vram)
-		{
 			m_video_ram[offset & 0x3fff] = data;
-		}
 
 		if (!ram1)
-		{
 			m_ram->pointer()[offset] = data;
-		}
 
 		if (!ram2 && HAS_KB_OF_RAM(96))
-		{
 			m_ram->pointer()[0x10000 | offset] = data;
-		}
 
 		if (!ram3 && HAS_KB_OF_RAM(128))
-		{
 			m_ram->pointer()[0x18000 | offset] = data;
-		}
 
 		if (!ram4 && HAS_KB_OF_RAM(160))
-		{
 			m_ram->pointer()[0x20000 | offset] = data;
-		}
 
 		if (!ram5 && HAS_KB_OF_RAM(192))
-		{
 			m_ram->pointer()[0x28000 | offset] = data;
-		}
 
 		if (!ram6 && HAS_KB_OF_RAM(224))
-		{
 			m_ram->pointer()[0x30000 | offset] = data;
-		}
 	}
 	else
 	{
@@ -591,12 +561,12 @@ MACHINE_CONFIG_START(bw2_state::bw2)
 	MCFG_PALETTE_INIT_OWNER(bw2_state, bw2)
 
 	// devices
-	MCFG_DEVICE_ADD(I8253_TAG, PIT8253, 0)
+	MCFG_DEVICE_ADD(m_pit, PIT8253, 0)
 	MCFG_PIT8253_CLK0(16_MHz_XTAL / 4) // 8251 USART TXC, RXC
-	MCFG_PIT8253_OUT0_HANDLER(WRITELINE(I8251_TAG, i8251_device, write_txc))
-	MCFG_DEVCB_CHAIN_OUTPUT(WRITELINE(I8251_TAG, i8251_device, write_rxc))
+	MCFG_PIT8253_OUT0_HANDLER(WRITELINE(m_uart, i8251_device, write_txc))
+	MCFG_DEVCB_CHAIN_OUTPUT(WRITELINE(m_uart, i8251_device, write_rxc))
 	MCFG_PIT8253_CLK1(11000) // LCD controller
-	MCFG_PIT8253_OUT1_HANDLER(WRITELINE(I8253_TAG, pit8253_device, write_clk2))
+	MCFG_PIT8253_OUT1_HANDLER(WRITELINE(m_pit, pit8253_device, write_clk2))
 	MCFG_PIT8253_CLK2(0) // Floppy /MTRON
 	MCFG_PIT8253_OUT2_HANDLER(WRITELINE(*this, bw2_state, mtron_w))
 
@@ -615,14 +585,14 @@ MACHINE_CONFIG_START(bw2_state::bw2)
 
 	MCFG_CENTRONICS_OUTPUT_LATCH_ADD("cent_data_out", CENTRONICS_TAG)
 
-	MCFG_DEVICE_ADD(I8251_TAG, I8251, 0)
+	MCFG_DEVICE_ADD(m_uart, I8251, 0)
 	MCFG_I8251_TXD_HANDLER(WRITELINE(RS232_TAG, rs232_port_device, write_txd))
 	MCFG_I8251_DTR_HANDLER(WRITELINE(RS232_TAG, rs232_port_device, write_dtr))
 	MCFG_I8251_RTS_HANDLER(WRITELINE(RS232_TAG, rs232_port_device, write_rts))
 
 	MCFG_DEVICE_ADD(RS232_TAG, RS232_PORT, default_rs232_devices, nullptr)
-	MCFG_RS232_RXD_HANDLER(WRITELINE(I8251_TAG, i8251_device, write_rxd))
-	MCFG_RS232_DSR_HANDLER(WRITELINE(I8251_TAG, i8251_device, write_dsr))
+	MCFG_RS232_RXD_HANDLER(WRITELINE(m_uart, i8251_device, write_rxd))
+	MCFG_RS232_DSR_HANDLER(WRITELINE(m_uart, i8251_device, write_dsr))
 
 	MCFG_DEVICE_ADD(WD2797_TAG, WD2797, 16_MHz_XTAL / 16)
 	MCFG_WD_FDC_INTRQ_CALLBACK(INPUTLINE(Z80_TAG, INPUT_LINE_IRQ0))
diff --git a/src/mame/drivers/jedi.cpp b/src/mame/drivers/jedi.cpp
index a827529ddef..1285b3e587e 100644
--- a/src/mame/drivers/jedi.cpp
+++ b/src/mame/drivers/jedi.cpp
@@ -341,9 +341,9 @@ MACHINE_CONFIG_START(jedi_state::jedi)
 
 	MCFG_DEVICE_ADD("adc", ADC0809, JEDI_AUDIO_CPU_OSC / 2 / 9) // nominally 666 kHz
 	MCFG_ADC0808_IN0_CB(IOPORT("STICKY"))
-	MCFG_ADC0808_IN1_CB(NOOP) // SPARE
+	MCFG_ADC0808_IN1_CB(CONSTANT(0)) // SPARE
 	MCFG_ADC0808_IN2_CB(IOPORT("STICKX"))
-	MCFG_ADC0808_IN3_CB(NOOP) // SPARE
+	MCFG_ADC0808_IN3_CB(CONSTANT(0)) // SPARE
 
 	MCFG_DEVICE_ADD("outlatch", LS259, 0) // 14J
 	MCFG_ADDRESSABLE_LATCH_Q0_OUT_CB(WRITELINE(*this, jedi_state, coin_counter_left_w))
diff --git a/src/mame/drivers/starwars.cpp b/src/mame/drivers/starwars.cpp
index 6e6bfa14c52..927394cf1a5 100644
--- a/src/mame/drivers/starwars.cpp
+++ b/src/mame/drivers/starwars.cpp
@@ -314,7 +314,7 @@ MACHINE_CONFIG_START(starwars_state::starwars)
 	MCFG_DEVICE_ADD("adc", ADC0809, MASTER_CLOCK / 16) // designated as "137243-001" on parts list and "157249-120" on schematics
 	MCFG_ADC0808_IN0_CB(IOPORT("STICKY")) // pitch
 	MCFG_ADC0808_IN1_CB(IOPORT("STICKX")) // yaw
-	MCFG_ADC0808_IN2_CB(GND) // thrust (unused)
+	MCFG_ADC0808_IN2_CB(CONSTANT(0)) // thrust (unused)
 
 	MCFG_DEVICE_ADD("riot", RIOT6532, MASTER_CLOCK / 8)
 	MCFG_RIOT6532_IN_PA_CB(READ8(*this, starwars_state, r6532_porta_r))
diff --git a/src/mame/drivers/subs.cpp b/src/mame/drivers/subs.cpp
index ffee6453e88..d4fde819fbd 100644
--- a/src/mame/drivers/subs.cpp
+++ b/src/mame/drivers/subs.cpp
@@ -210,9 +210,7 @@ MACHINE_CONFIG_START(subs_state::subs)
 	SPEAKER(config, "lspeaker").front_left();
 	SPEAKER(config, "rspeaker").front_right();
 
-	MCFG_DEVICE_ADD("discrete", DISCRETE, subs_discrete)
-	MCFG_SOUND_ROUTE(0, "lspeaker", 1.0)
-	MCFG_SOUND_ROUTE(1, "rspeaker", 1.0)
+	DISCRETE(config, m_discrete, subs_discrete).add_route(0, "lspeaker", 1.0).add_route(1, "rspeaker", 1.0);
 
 	MCFG_DEVICE_ADD("latch", LS259, 0) // C9
 	MCFG_ADDRESSABLE_LATCH_Q0_OUT_CB(OUTPUT("led0")) MCFG_DEVCB_INVERT // START LAMP 1
diff --git a/src/mame/drivers/wmg.cpp b/src/mame/drivers/wmg.cpp
index 46e19d27ed3..372f1fb4185 100644
--- a/src/mame/drivers/wmg.cpp
+++ b/src/mame/drivers/wmg.cpp
@@ -72,6 +72,7 @@ of save-state is also needed.
 #include "includes/williams.h"
 
 #include "cpu/m6800/m6800.h"
+#include "machine/input_merger.h"
 #include "machine/nvram.h"
 #include "sound/dac.h"
 #include "sound/volt_reg.h"
@@ -135,7 +136,7 @@ void wmg_state::wmg_cpu2(address_map &map)
 {
 	map(0x0000, 0x007f).ram();     /* internal RAM */
 	map(0x0080, 0x00ff).ram();     /* MC6810 RAM */
-	map(0x0400, 0x0403).mirror(0x8000).rw(m_pia_2, FUNC(pia6821_device::read), FUNC(pia6821_device::write));
+	map(0x0400, 0x0403).mirror(0x8000).rw(m_pia[2], FUNC(pia6821_device::read), FUNC(pia6821_device::write));
 /* These next 2 are actually banked in CPU 1, but its not something Mame can handle very well. Placed here instead. */
 	map(0xc000, 0xc00f).mirror(0x03f0).writeonly().share("paletteram");
 	map(0xd000, 0xefff).ram().share("nvram");
@@ -391,17 +392,14 @@ WRITE8_MEMBER( wmg_state::wmg_d000_w )
 	if (data == 0)
 	{
 		/* install the i/o devices into c000-cfff */
-		pia6821_device *pia0 = m_pia_0;
-		pia6821_device *pia1 = m_pia_1;
-
 		space.unmap_read(0xc000, 0xcfff); // throw out bank7
 		space.install_write_bank       (0xc000, 0xc00f, "bank4");
-		membank("bank4")->set_base(m_generic_paletteram_8);
+		membank("bank4")->set_base(m_paletteram);
 		space.install_write_handler    (0xc010, 0xc01f, write8_delegate(FUNC(williams_state::defender_video_control_w),this));
 		space.install_write_handler    (0xc400, 0xc400, write8_delegate(FUNC(wmg_state::wmg_c400_w),this));
 		space.install_write_handler    (0xc401, 0xc401, write8_delegate(FUNC(wmg_state::wmg_sound_reset_w),this));
-		space.install_readwrite_handler(0xc804, 0xc807, read8_delegate(FUNC(wmg_state::wmg_pia_0_r),this), write8_delegate(FUNC(pia6821_device::write), pia0));
-		space.install_readwrite_handler(0xc80c, 0xc80f, read8_delegate(FUNC(pia6821_device::read), pia1), write8_delegate(FUNC(pia6821_device::write), pia1));
+		space.install_readwrite_handler(0xc804, 0xc807, read8_delegate(FUNC(wmg_state::wmg_pia_0_r),this), write8_delegate(FUNC(pia6821_device::write), m_pia[0].target()));
+		space.install_readwrite_handler(0xc80c, 0xc80f, read8_delegate(FUNC(pia6821_device::read), m_pia[1].target()), write8_delegate(FUNC(pia6821_device::write), m_pia[1].target()));
 		space.install_write_handler    (0xc900, 0xc9ff, write8_delegate(FUNC(wmg_state::wmg_vram_select_w),this));
 		space.install_write_handler    (0xca00, 0xca07, write8_delegate(FUNC(williams_state::williams_blitter_w),this));
 		space.install_write_handler    (0xcbff, 0xcbff, write8_delegate(FUNC(williams_state::williams_watchdog_reset_w),this));
@@ -457,7 +455,7 @@ READ8_MEMBER( wmg_state::wmg_pia_0_r )
     Since there is no code in rom to handle this, it must be a hardware feature
     which probably just resets the cpu. */
 
-	uint8_t data = m_pia_0->read(space, offset);
+	uint8_t data = m_pia[0]->read(space, offset);
 
 	if ((m_wmg_c400) && (offset == 0) && ((data & 0x30) == 0x30))   // P1 and P2 pressed
 	{
@@ -526,6 +524,12 @@ MACHINE_CONFIG_START(wmg_state::wmg)
 	MCFG_SOUND_ROUTE(0, "dac", 1.0, DAC_VREF_POS_INPUT) MCFG_SOUND_ROUTE(0, "dac", -1.0, DAC_VREF_NEG_INPUT)
 
 	/* pia */
+	MCFG_INPUT_MERGER_ANY_HIGH("mainirq")
+	MCFG_INPUT_MERGER_OUTPUT_HANDLER(INPUTLINE("maincpu", M6809_IRQ_LINE))
+
+	MCFG_INPUT_MERGER_ANY_HIGH("soundirq")
+	MCFG_INPUT_MERGER_OUTPUT_HANDLER(INPUTLINE("soundcpu", M6808_IRQ_LINE))
+
 	MCFG_DEVICE_ADD("pia_0", PIA6821, 0)
 	MCFG_PIA_READPA_HANDLER(IOPORT("IN0"))
 	MCFG_PIA_READPB_HANDLER(IOPORT("IN1"))
@@ -534,13 +538,13 @@ MACHINE_CONFIG_START(wmg_state::wmg)
 	MCFG_DEVICE_ADD("pia_1", PIA6821, 0)
 	MCFG_PIA_READPA_HANDLER(IOPORT("IN2"))
 	MCFG_PIA_WRITEPB_HANDLER(WRITE8(*this, williams_state, williams_snd_cmd_w))
-	MCFG_PIA_IRQA_HANDLER(WRITELINE(*this, williams_state, williams_main_irq))
-	MCFG_PIA_IRQB_HANDLER(WRITELINE(*this, williams_state, williams_main_irq))
+	MCFG_PIA_IRQA_HANDLER(WRITELINE("mainirq", input_merger_any_high_device, in_w<0>))
+	MCFG_PIA_IRQB_HANDLER(WRITELINE("mainirq", input_merger_any_high_device, in_w<1>))
 
 	MCFG_DEVICE_ADD("pia_2", PIA6821, 0)
 	MCFG_PIA_WRITEPA_HANDLER(WRITE8("dac", dac_byte_interface, data_w))
-	MCFG_PIA_IRQA_HANDLER(WRITELINE(*this, williams_state,williams_snd_irq))
-	MCFG_PIA_IRQB_HANDLER(WRITELINE(*this, williams_state,williams_snd_irq))
+	MCFG_PIA_IRQA_HANDLER(WRITELINE("soundirq", input_merger_any_high_device, in_w<0>))
+	MCFG_PIA_IRQB_HANDLER(WRITELINE("soundirq", input_merger_any_high_device, in_w<1>))
 MACHINE_CONFIG_END
 
 /*************************************
diff --git a/src/mame/includes/bebox.h b/src/mame/includes/bebox.h
index 3fd522cce94..23f57d0f578 100644
--- a/src/mame/includes/bebox.h
+++ b/src/mame/includes/bebox.h
@@ -32,19 +32,19 @@ public:
 	};
 
 	bebox_state(const machine_config &mconfig, device_type type, const char *tag)
-		: driver_device(mconfig, type, tag),
-			m_ppc1(*this, "ppc1"),
-			m_ppc2(*this, "ppc2"),
-			m_lsi53c810(*this, "lsi53c810"),
-			m_dma8237_1(*this, "dma8237_1"),
-			m_dma8237_2(*this, "dma8237_2"),
-			m_pic8259_1(*this, "pic8259_1"),
-			m_pic8259_2(*this, "pic8259_2"),
-			m_pit8254(*this, "pit8254"),
-			m_ram(*this, RAM_TAG),
-			m_smc37c78(*this, "smc37c78"),
-			m_flash(*this, "flash"),
-			m_pcibus(*this, "pcibus")
+		: driver_device(mconfig, type, tag)
+		, m_ppc1(*this, "ppc1")
+		, m_ppc2(*this, "ppc2")
+		, m_lsi53c810(*this, "lsi53c810")
+		, m_dma8237_1(*this, "dma8237_1")
+		, m_dma8237_2(*this, "dma8237_2")
+		, m_pic8259_1(*this, "pic8259_1")
+		, m_pic8259_2(*this, "pic8259_2")
+		, m_pit8254(*this, "pit8254")
+		, m_ram(*this, RAM_TAG)
+		, m_smc37c78(*this, "smc37c78")
+		, m_flash(*this, "flash")
+		, m_pcibus(*this, "pcibus")
 	{
 	}
 
diff --git a/src/mame/includes/bw2.h b/src/mame/includes/bw2.h
index a41998a7f3d..ee692f30b71 100644
--- a/src/mame/includes/bw2.h
+++ b/src/mame/includes/bw2.h
@@ -21,8 +21,6 @@
 #define Z80_TAG         "ic1"
 #define I8255A_TAG      "ic4"
 #define WD2797_TAG      "ic5"
-#define I8253_TAG       "ic6"
-#define I8251_TAG       "ic7"
 #define MSM6255_TAG     "ic49"
 #define CENTRONICS_TAG  "centronics"
 #define RS232_TAG       "rs232"
@@ -34,10 +32,10 @@ public:
 	bw2_state(const machine_config &mconfig, device_type type, const char *tag) :
 		driver_device(mconfig, type, tag),
 		m_maincpu(*this, Z80_TAG),
-		m_uart(*this, I8251_TAG),
+		m_uart(*this, "ic7"),
 		m_fdc(*this, WD2797_TAG),
 		m_lcdc(*this, MSM6255_TAG),
-		m_pit(*this, I8253_TAG),
+		m_pit(*this, "ic6"),
 		m_centronics(*this, CENTRONICS_TAG),
 		m_exp(*this, BW2_EXPANSION_SLOT_TAG),
 		m_ram(*this, RAM_TAG),
diff --git a/src/mame/includes/starwars.h b/src/mame/includes/starwars.h
index 2baffe9ea2c..98459efcc05 100644
--- a/src/mame/includes/starwars.h
+++ b/src/mame/includes/starwars.h
@@ -5,6 +5,10 @@
     Atari Star Wars hardware
 
 ***************************************************************************/
+#ifndef MAME_INCLUDES_STARWARS_H
+#define MAME_INCLUDES_STARWARS_H
+
+#pragma once
 
 #include "machine/6532riot.h"
 #include "machine/gen_latch.h"
@@ -17,8 +21,8 @@
 class starwars_state : public driver_device
 {
 public:
-	starwars_state(const machine_config &mconfig, device_type type, const char *tag)
-		: driver_device(mconfig, type, tag),
+	starwars_state(const machine_config &mconfig, device_type type, const char *tag) :
+		driver_device(mconfig, type, tag),
 		m_soundlatch(*this, "soundlatch"),
 		m_mainlatch(*this, "mainlatch"),
 		m_riot(*this, "riot"),
@@ -29,7 +33,7 @@ public:
 		m_tms(*this, "tms"),
 		m_novram(*this, "x2212"),
 		m_slapstic_device(*this, "slapstic")
-		{ }
+	{ }
 
 	required_device<generic_latch_8_device> m_soundlatch;
 	required_device<generic_latch_8_device> m_mainlatch;
@@ -93,3 +97,5 @@ public:
 	void main_map(address_map &map);
 	void sound_map(address_map &map);
 };
+
+#endif // MAME_INCLUDES_STARWARS_H
diff --git a/src/mame/includes/subs.h b/src/mame/includes/subs.h
index 75ea487ab52..6c420fb57fb 100644
--- a/src/mame/includes/subs.h
+++ b/src/mame/includes/subs.h
@@ -24,14 +24,15 @@
 class subs_state : public driver_device
 {
 public:
-	subs_state(const machine_config &mconfig, device_type type, const char *tag)
-		: driver_device(mconfig, type, tag),
+	subs_state(const machine_config &mconfig, device_type type, const char *tag) :
+		driver_device(mconfig, type, tag),
 		m_maincpu(*this, "maincpu"),
 		m_gfxdecode(*this, "gfxdecode"),
 		m_palette(*this, "palette"),
 		m_discrete(*this, "discrete"),
 		m_spriteram(*this, "spriteram"),
-		m_videoram(*this, "videoram") { }
+		m_videoram(*this, "videoram")
+	{ }
 
 	required_device<cpu_device> m_maincpu;
 	required_device<gfxdecode_device> m_gfxdecode;