diff --git a/src/mame/drivers/v100.cpp b/src/mame/drivers/v100.cpp
index e7d66a7937b..1b6969d6f4d 100644
--- a/src/mame/drivers/v100.cpp
+++ b/src/mame/drivers/v100.cpp
@@ -74,8 +74,8 @@ private:
 	required_shared_ptr<u8> m_videoram;
 	optional_ioport_array<16> m_key_row;
 
-	u8 m_active_row;
-	bool m_video_enable;
+	u8 m_active_row = 0;
+	bool m_video_enable = false;
 };
 
 u32 v100_state::screen_update(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect)
diff --git a/src/mame/drivers/v102.cpp b/src/mame/drivers/v102.cpp
index 3bc68cfc117..c8b25fedd72 100644
--- a/src/mame/drivers/v102.cpp
+++ b/src/mame/drivers/v102.cpp
@@ -49,8 +49,8 @@ private:
 	required_device<upd7201_device> m_mpsc;
 	required_region_ptr<u8> m_chargen;
 
-	bool m_hs_state;
-	bool m_kb_clock;
+	bool m_hs_state = false;
+	bool m_kb_clock = false;
 };
 
 
diff --git a/src/mame/drivers/v6809.cpp b/src/mame/drivers/v6809.cpp
index 69e9467ecda..8d7e6ed8c06 100644
--- a/src/mame/drivers/v6809.cpp
+++ b/src/mame/drivers/v6809.cpp
@@ -103,7 +103,7 @@ private:
 	void v6809_mem(address_map &map);
 
 	u16 m_video_address = 0U;
-	bool m_speaker_en = 0;
+	bool m_speaker_en = false;
 	u8 m_video_index = 0U;
 	u8 m_term_data = 0U;
 	u8 m_vidbyte = 0U;
@@ -336,7 +336,7 @@ void v6809_state::v6809(machine_config &config)
 	pia1.irqb_handler().set_inputline("maincpu", M6809_IRQ_LINE);
 
 	ptm6840_device &ptm(PTM6840(config, "ptm", 16_MHz_XTAL / 4));
-	ptm.set_external_clocks(4000000/14, 4000000/14, 4000000/14/8);
+	ptm.set_external_clocks(4000000.0/14.0, 4000000.0/14.0, (4000000.0/14.0)/8.0);
 	ptm.o1_callback().set(FUNC(v6809_state::speaker_en_w));
 	ptm.o2_callback().set(FUNC(v6809_state::speaker_w));
 	ptm.irq_callback().set_inputline("maincpu", M6809_IRQ_LINE);
diff --git a/src/mame/drivers/vamphalf.cpp b/src/mame/drivers/vamphalf.cpp
index 7cfe2408b17..1446125f827 100644
--- a/src/mame/drivers/vamphalf.cpp
+++ b/src/mame/drivers/vamphalf.cpp
@@ -299,7 +299,7 @@ private:
 
 	required_device<nvram_device> m_nvram;
 
-	u16 m_finalgdr_backupram_bank;
+	u16 m_finalgdr_backupram_bank = 0;
 	std::unique_ptr<u8[]> m_finalgdr_backupram;
 	void finalgdr_backupram_bank_w(u32 data);
 	u32 finalgdr_backupram_r(offs_t offset);
diff --git a/src/mame/drivers/vax11.cpp b/src/mame/drivers/vax11.cpp
index 01c16de4fe8..89fc7d16003 100644
--- a/src/mame/drivers/vax11.cpp
+++ b/src/mame/drivers/vax11.cpp
@@ -90,8 +90,8 @@ private:
 	uint16_t term_rx_status_r();
 	void term_w(uint16_t data);
 	void kbd_put(u8 data);
-	uint8_t m_term_data;
-	uint16_t m_term_status;
+	uint8_t m_term_data = 0;
+	uint16_t m_term_status = 0;
 	void vax11_mem(address_map &map);
 };
 
diff --git a/src/mame/drivers/vboy.cpp b/src/mame/drivers/vboy.cpp
index 5ea9744e27b..16a689781d3 100644
--- a/src/mame/drivers/vboy.cpp
+++ b/src/mame/drivers/vboy.cpp
@@ -140,10 +140,10 @@ private:
 	vip_regs_t m_vip_regs;
 	vboy_timer_t m_vboy_timer;
 	std::unique_ptr<int32_t[]> m_ovr_tempdraw_map;
-	uint16_t m_frame_count;
-	uint8_t m_displayfb;
-	uint8_t m_drawfb;
-	uint8_t m_row_num;
+	uint16_t m_frame_count = 0;
+	uint8_t m_displayfb = 0;
+	uint8_t m_drawfb = 0;
+	uint8_t m_row_num = 0;
 	attotime m_input_latch_time;
 
 	uint32_t io_r(offs_t offset);
diff --git a/src/mame/drivers/vcombat.cpp b/src/mame/drivers/vcombat.cpp
index d51a4648c3b..ddb2e29853c 100644
--- a/src/mame/drivers/vcombat.cpp
+++ b/src/mame/drivers/vcombat.cpp
@@ -143,7 +143,7 @@ private:
 
 	std::unique_ptr<uint16_t[]> m_m68k_framebuffer[2];
 	std::unique_ptr<uint16_t[]> m_i860_framebuffer[2][2];
-	int m_crtc_select;
+	int m_crtc_select = 0;
 
 	void main_video_write(offs_t offset, uint16_t data, uint16_t mem_mask = ~0);
 	uint16_t control_1_r();
diff --git a/src/mame/drivers/vdm7932x.cpp b/src/mame/drivers/vdm7932x.cpp
index 71c630b8d0f..4ced0d44493 100644
--- a/src/mame/drivers/vdm7932x.cpp
+++ b/src/mame/drivers/vdm7932x.cpp
@@ -41,7 +41,7 @@ private:
 
 	required_device<z80_device> m_maincpu;
 	required_device<i8031_device> m_subcpu;
-	bool m_obfa;
+	bool m_obfa = false;
 };
 
 
diff --git a/src/mame/drivers/vega.cpp b/src/mame/drivers/vega.cpp
index 7f09e828336..5b9251df65b 100644
--- a/src/mame/drivers/vega.cpp
+++ b/src/mame/drivers/vega.cpp
@@ -113,7 +113,7 @@ protected:
 private:
 	struct vega_obj
 	{
-		int m_x, m_y, m_enable, m_type;
+		int m_x = 0, m_y = 0, m_enable = 0, m_type = 0;
 	};
 
 	enum
@@ -134,20 +134,20 @@ private:
 	required_device<gfxdecode_device> m_gfxdecode;
 	required_device<palette_device> m_palette;
 
-	int m_p2_data;
-	int m_ext_offset_w;
-	int m_ext_offset_r;
+	int m_p2_data = 0;
+	int m_ext_offset_w = 0;
+	int m_ext_offset_r = 0;
 
-	int m_tmp;
-	int m_t1;
+	int m_tmp = 0;
+	int m_t1 = 0;
 
-	uint8_t m_txt_ram[0x400];
+	uint8_t m_txt_ram[0x400]{};
 
 	vega_obj    m_obj[NUM_OBJ];
 
-	int m_frame_counter;
+	int m_frame_counter = 0;
 
-	int m_tilemap_offset_x, m_tilemap_offset_y, m_tilemap_flags, m_tilemap_top;
+	int m_tilemap_offset_x = 0, m_tilemap_offset_y = 0, m_tilemap_flags = 0, m_tilemap_top = 0;
 
 	uint8_t extern_r(offs_t offset);
 	void extern_w(offs_t offset, uint8_t data);
diff --git a/src/mame/drivers/vg5k.cpp b/src/mame/drivers/vg5k.cpp
index 7dd0c100c9d..d6671cd1531 100644
--- a/src/mame/drivers/vg5k.cpp
+++ b/src/mame/drivers/vg5k.cpp
@@ -91,9 +91,9 @@ private:
 	required_device<cassette_image_device> m_cassette;
 	required_device<ram_device> m_ram;
 
-	offs_t m_ef9345_offset;
-	uint8_t m_printer_latch;
-	uint8_t m_printer_signal;
+	offs_t m_ef9345_offset = 0;
+	uint8_t m_printer_latch = 0;
+	uint8_t m_printer_signal = 0;
 
 	virtual void machine_start() override;
 	virtual void machine_reset() override;
diff --git a/src/mame/drivers/vgmplay.cpp b/src/mame/drivers/vgmplay.cpp
index a9195086193..aa107e29af4 100644
--- a/src/mame/drivers/vgmplay.cpp
+++ b/src/mame/drivers/vgmplay.cpp
@@ -306,24 +306,24 @@ private:
 
 	struct stream
 	{
-		uint8_t byte_depth;
-		uint32_t position;
-		emu_timer *timer;
+		uint8_t byte_depth = 0;
+		uint32_t position = 0;
+		emu_timer *timer = nullptr;
 		// stream control
 		vgm_chip chip_type;
-		uint8_t port;
-		uint8_t reg;
+		uint8_t port = 0;
+		uint8_t reg = 0;
 		// stream data
-		uint8_t bank;
-		uint8_t step_size;
-		uint8_t step_base;
+		uint8_t bank = 0;
+		uint8_t step_size = 0;
+		uint8_t step_base = 0;
 		// frequency
-		uint32_t frequency;
+		uint32_t frequency = 0;
 		// start stream
-		uint32_t offset;
-		uint32_t length;
-		bool loop;
-		bool reverse;
+		uint32_t offset = 0;
+		uint32_t length = 0;
+		bool loop = false;
+		bool reverse = false;
 	};
 
 	TIMER_CALLBACK_MEMBER(stream_timer_expired);
@@ -387,9 +387,9 @@ private:
 	uint32_t m_okim6295_bank[2];
 	uint32_t m_okim6295_nmk112_bank[2][4];
 
-	C140_TYPE m_c140_bank[2];
+	C140_TYPE m_c140_bank[2]{};
 
-	int m_sega32x_channel_hack;
+	int m_sega32x_channel_hack = 0;
 	int m_nes_apu_channel_hack[2];
 	uint8_t m_c6280_channel[2];
 
diff --git a/src/mame/drivers/video21.cpp b/src/mame/drivers/video21.cpp
index ec6252b202c..d6f9e5f5c9c 100644
--- a/src/mame/drivers/video21.cpp
+++ b/src/mame/drivers/video21.cpp
@@ -57,7 +57,7 @@ private:
 
 	int m_hopper_motor = 0;
 	int m_hopper_coin = 0;
-	emu_timer *m_hopper_timer;
+	emu_timer *m_hopper_timer = nullptr;
 	TIMER_CALLBACK_MEMBER(hopper_coinout);
 
 	uint32_t screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);