fixed multisession crash when the new cart needed a dynamic buffer/array

larger than the original one. this got introduced when converting from 
auto_alloc_array to dynamic buffers, because such buffers are not made
NULL at reset, but got unnoticed/unreported up to now. many thanks to 
Trebor for catching it! nw.

src/emu/bus/a7800/a78_slot.c

@@ -61,8 +61,6 @@ device_a78_cart_interface::~device_a78_cart_interface ()
 //-------------------------------------------------
 
 void device_a78_cart_interface::rom_alloc(UINT32 size)
-{
-	if (m_rom == NULL)
 {
 	m_rom.resize(size);
 	
@@ -77,20 +75,16 @@ void device_a78_cart_interface::rom_alloc(UINT32 size)
 	// the access handling
 	m_base_rom = 0x10000 - size;
 }
-}
 
 //-------------------------------------------------
 //  ram_alloc - alloc the space for the on-cart RAM
 //-------------------------------------------------
 
 void device_a78_cart_interface::ram_alloc(UINT32 size)
-{
-	if (m_ram == NULL)
 {
 	m_ram.resize(size);
 	device().save_item(NAME(m_ram));
 }
-}
 
 
 //-------------------------------------------------
@@ -98,13 +92,10 @@ void device_a78_cart_interface::ram_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_a78_cart_interface::nvram_alloc(UINT32 size)
-{
-	if (m_nvram == NULL)
 {
 	m_nvram.resize(size);
 	device().save_item(NAME(m_nvram));
 }
-}
 
 
 
@@ -120,7 +111,6 @@ a78_cart_slot_device::a78_cart_slot_device(const machine_config &mconfig, const
 						device_image_interface(mconfig, *this),
 						device_slot_interface(mconfig, *this)
 {
-	m_type = A78_NOCART;
 }
 
 
@@ -321,8 +311,7 @@ static const a78_slot slot_list[] =
 	{ A78_TYPE1_POK450, "a78_p450_t1" },
 	{ A78_TYPE6_POK450, "a78_p450_t6" },
 	{ A78_TYPEA_POK450, "a78_p450_ta" },
-	{ A78_VERSA_POK450, "a78_p450_vb" },
+	{ A78_VERSA_POK450, "a78_p450_vb" }
-	{ A78_NOCART,     "empty" },	// the code should never get here, of course...
 };
 
 static int a78_get_pcb_id(const char *slot)

src/emu/bus/a7800/a78_slot.h

@@ -30,8 +30,7 @@ enum
 	A78_TYPE1_POK450 = 0x21,
 	A78_TYPE6_POK450 = 0x24,
 	A78_TYPEA_POK450 = 0x25,
-	A78_VERSA_POK450 = 0x30,
+	A78_VERSA_POK450 = 0x30
-	A78_NOCART
 };
 
 

src/emu/bus/a800/a800_slot.c

@@ -58,28 +58,22 @@ device_a800_cart_interface::~device_a800_cart_interface ()
 //-------------------------------------------------
 
 void device_a800_cart_interface::rom_alloc(UINT32 size)
-{
-	if (m_rom == NULL)
 {
 	m_rom.resize(size);
 	
 	// setup other helpers
 	m_bank_mask = (size / 0x2000) - 1;	// code for XEGS carts makes use of this to simplify banking
 }
-}
 
 //-------------------------------------------------
 //  ram_alloc - alloc the space for the on-cart RAM
 //-------------------------------------------------
 
 void device_a800_cart_interface::ram_alloc(UINT32 size)
-{
-	if (m_ram == NULL)
 {
 	m_ram.resize(size);
 	device().save_item(NAME(m_ram));
 }
-}
 
 
 //-------------------------------------------------
@@ -87,13 +81,10 @@ void device_a800_cart_interface::ram_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_a800_cart_interface::nvram_alloc(UINT32 size)
-{
-	if (m_nvram == NULL)
 {
 	m_nvram.resize(size);
 	device().save_item(NAME(m_nvram));
 }
-}
 
 
 
@@ -109,7 +100,6 @@ a800_cart_slot_device::a800_cart_slot_device(const machine_config &mconfig, devi
 						device_image_interface(mconfig, *this),
 						device_slot_interface(mconfig, *this)
 {
-	m_type = A800_NOCART;
 }
 
 a800_cart_slot_device::a800_cart_slot_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) :
@@ -117,7 +107,6 @@ a800_cart_slot_device::a800_cart_slot_device(const machine_config &mconfig, cons
 						device_image_interface(mconfig, *this),
 						device_slot_interface(mconfig, *this)
 {
-	m_type = A800_NOCART;
 }
 
 
@@ -215,8 +204,7 @@ static const a800_slot slot_list[] =
 	{ A5200_32K,      "a5200" },
 	{ A5200_16K_2CHIPS, "a5200_2chips" },
 	{ A5200_32K,      "a5200" },
-	{ A5200_BBSB,     "a5200_bbsb" },
+	{ A5200_BBSB,     "a5200_bbsb" }
-	{ A800_NOCART,    "empty" },
 };
 
 

src/emu/bus/a800/a800_slot.h

@@ -37,8 +37,7 @@ enum
 	A5200_16K,
 	A5200_32K,
 	A5200_16K_2CHIPS,
-	A5200_BBSB,
+	A5200_BBSB
-	A800_NOCART
 };
 
 

src/emu/bus/gameboy/gb_slot.c

@@ -57,7 +57,6 @@ device_gb_cart_interface::~device_gb_cart_interface()
 
 void device_gb_cart_interface::rom_alloc(UINT32 size)
 {
-	if (m_rom == NULL)
 	m_rom.resize(size);
 }
 
@@ -67,13 +66,10 @@ void device_gb_cart_interface::rom_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_gb_cart_interface::ram_alloc(UINT32 size)
-{
-	if (m_ram == NULL)
 {
 	m_ram.resize(size);
 	device().save_item(NAME(m_ram));
 }
-}
 
 
 //-------------------------------------------------

src/emu/bus/gba/gba_slot.c

@@ -45,13 +45,10 @@ device_gba_cart_interface::~device_gba_cart_interface()
 //-------------------------------------------------
 
 void device_gba_cart_interface::nvram_alloc(UINT32 size)
-{
-	if (m_nvram == NULL)
 {
 	m_nvram.resize(size/sizeof(UINT32));
 	device().save_item(NAME(m_nvram));
 }
-}
 
 
 //**************************************************************************

src/emu/bus/megadrive/md_slot.c

@@ -97,13 +97,10 @@ void device_md_cart_interface::rom_alloc(size_t size, const char *tag)
 //-------------------------------------------------
 
 void device_md_cart_interface::nvram_alloc(size_t size)
-{
-	if (m_nvram == NULL)
 {
 	m_nvram.resize(size/sizeof(UINT16));
 	device().save_item(NAME(m_nvram));
 }
-}
 
 //-------------------------------------------------
 //  rom_map_setup - setup map of rom banks in 64K

src/emu/bus/megadrive/md_slot.h

@@ -78,13 +78,6 @@ enum
 };
 
 
-// ======================> md_cart_interface
-
-struct md_cart_interface
-{
-};
-
-
 // ======================> device_md_cart_interface
 
 class device_md_cart_interface : public device_slot_card_interface
@@ -138,7 +131,6 @@ public:
 // ======================> base_md_cart_slot_device
 
 class base_md_cart_slot_device : public device_t,
-								public md_cart_interface,
 								public device_image_interface,
 								public device_slot_interface
 {

src/emu/bus/nes/nes_slot.c

@@ -141,8 +141,6 @@ device_nes_cart_interface::~device_nes_cart_interface()
 //-------------------------------------------------
 
 void device_nes_cart_interface::prg_alloc(size_t size)
-{
-	if (m_prg == NULL)
 {
 	m_prg.resize(size);
 	m_prg_chunks = size / 0x4000;
@@ -204,35 +202,26 @@ void device_nes_cart_interface::prg_alloc(size_t size)
 //          }
 	}
 }
-}
 
 void device_nes_cart_interface::prgram_alloc(size_t size)
 {
-	if (m_prgram == NULL)
 	m_prgram.resize(size);
 }
 
 void device_nes_cart_interface::vrom_alloc(size_t size)
-{
-	if (m_vrom == NULL)
 {
 	m_vrom.resize(size);
 	m_vrom_chunks = size / 0x2000;
 }
-}
 
 void device_nes_cart_interface::vram_alloc(size_t size)
-{
-	if (m_vram == NULL)
 {
 	m_vram.resize(size);
 	m_vram_chunks = size / 0x2000;
 }
-}
 
 void device_nes_cart_interface::battery_alloc(size_t size)
 {
-	if (m_battery == NULL)
 	m_battery.resize(size);
 }
 

src/emu/bus/pce/pce_slot.c

@@ -44,7 +44,6 @@ device_pce_cart_interface::~device_pce_cart_interface()
 
 void device_pce_cart_interface::rom_alloc(UINT32 size)
 {
-	if (m_rom == NULL)
 	m_rom.resize(size);
 }
 
@@ -54,13 +53,10 @@ void device_pce_cart_interface::rom_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_pce_cart_interface::ram_alloc(UINT32 size)
-{
-	if (m_ram == NULL)
 {
 	m_ram.resize(size);
 	device().save_item(NAME(m_ram));
 }
-}
 
 //-------------------------------------------------
 //  rom_map_setup - setup map of rom banks in 128K
@@ -69,8 +65,6 @@ void device_pce_cart_interface::ram_alloc(UINT32 size)
 
 void device_pce_cart_interface::rom_map_setup(UINT32 size)
 {
-	int i;
-
 	if (size == 0x60000)
 	{
 		// HuCard 384K are mapped with mirrored pieces
@@ -85,6 +79,8 @@ void device_pce_cart_interface::rom_map_setup(UINT32 size)
 	}
 	else
 	{
+		int i;
+
 		// setup the rom_bank_map array to faster ROM read
 		for (i = 0; i < size / 0x20000 && i < 8; i++)
 			rom_bank_map[i] = i;

src/emu/bus/saturn/sat_slot.c

@@ -54,7 +54,6 @@ device_sat_cart_interface::~device_sat_cart_interface()
 
 void device_sat_cart_interface::rom_alloc(UINT32 size)
 {
-	if (m_rom == NULL)
 	m_rom.resize(size/sizeof(UINT32));
 }
 

src/emu/bus/sega8/sega8_slot.c

@@ -71,8 +71,6 @@ device_sega8_cart_interface::~device_sega8_cart_interface()
 //-------------------------------------------------
 
 void device_sega8_cart_interface::rom_alloc(UINT32 size)
-{
-	if (m_rom == NULL)
 {
 	m_rom.resize(size);
 	m_rom_page_count = size / 0x4000;
@@ -80,7 +78,6 @@ void device_sega8_cart_interface::rom_alloc(UINT32 size)
 		m_rom_page_count = 1;   // we compute rom pages through (XXX % m_rom_page_count)!
 	late_bank_setup();
 }
-}
 
 
 //-------------------------------------------------
@@ -88,13 +85,10 @@ void device_sega8_cart_interface::rom_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_sega8_cart_interface::ram_alloc(UINT32 size)
-{
-	if (m_ram == NULL)
 {
 	m_ram.resize(size);
 	device().save_item(NAME(m_ram));
 }
-}
 
 
 

src/emu/bus/snes/snes_slot.c

@@ -86,7 +86,6 @@ device_sns_cart_interface::~device_sns_cart_interface()
 
 void device_sns_cart_interface::rom_alloc(UINT32 size)
 {
-	if (m_rom == NULL)
 	m_rom.resize(size);
 }
 
@@ -96,13 +95,10 @@ void device_sns_cart_interface::rom_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_sns_cart_interface::nvram_alloc(UINT32 size)
-{
-	if (m_nvram == NULL)
 {
 	m_nvram.resize(size);
 	device().save_item(NAME(m_nvram));
 }
-}
 
 
 //-------------------------------------------------
@@ -113,13 +109,10 @@ void device_sns_cart_interface::nvram_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_sns_cart_interface::rtc_ram_alloc(UINT32 size)
-{
-	if (m_rtc_ram == NULL)
 {
 	m_rtc_ram.resize(size);
 	device().save_item(NAME(m_rtc_ram));
 }
-}
 
 
 //-------------------------------------------------
@@ -129,7 +122,6 @@ void device_sns_cart_interface::rtc_ram_alloc(UINT32 size)
 
 void device_sns_cart_interface::addon_bios_alloc(UINT32 size)
 {
-	if (m_bios == NULL)
 	m_bios.resize(size);
 }
 

src/emu/bus/vcs/vcs_slot.c

@@ -47,7 +47,6 @@ device_vcs_cart_interface::~device_vcs_cart_interface()
 
 void device_vcs_cart_interface::rom_alloc(UINT32 size)
 {
-	if (m_rom == NULL)
 	m_rom.resize(size);
 }
 
@@ -56,13 +55,10 @@ void device_vcs_cart_interface::rom_alloc(UINT32 size)
 //-------------------------------------------------
 
 void device_vcs_cart_interface::ram_alloc(UINT32 size)
-{
-	if (m_ram == NULL)
 {
 	m_ram.resize(size);
 	device().save_item(NAME(m_ram));
 }
-}
 
 
 

src/mess/drivers/a7800.c

@@ -1315,7 +1315,7 @@ void a7800_state::machine_start()
 	save_item(NAME(m_maria_flag));
 	
 	// install additional handlers, if needed
-	switch (m_cartslot->get_cart_type())
+	switch (m_cartslot->exists() && m_cartslot->get_cart_type())
 	{
 		case A78_HSC:
 			// ROM+NVRAM accesses for HiScore

src/mess/drivers/atari400.c

@@ -1735,7 +1735,7 @@ READ8_MEMBER(a400_state::read_d5xx)
 
 WRITE8_MEMBER(a400_state::disable_cart)
 {
-	switch (m_cartslot->get_cart_type())
+	switch (m_cartslot->exists() && m_cartslot->get_cart_type())
 	{
 		case A800_PHOENIX:
 		case A800_BLIZZARD:
@@ -1834,7 +1834,7 @@ void a400_state::setup_cart(a800_cart_slot_device *slot)
 	m_cart_disabled = 0;
 	m_last_offs = -1;
 
-	switch (slot->get_cart_type())
+	switch (slot->exists() && slot->get_cart_type())
 	{
 		case A800_8K:
 			m_maincpu->space(AS_PROGRAM).install_read_handler(0xa000, 0xbfff, read8_delegate(FUNC(a800_cart_slot_device::read_80xx),(a800_cart_slot_device*)slot));