// license:BSD-3-Clause // copyright-holders:etabeta /*********************************************************************************************************** A7800 CPUWIZ's homebrew boards (MegaCart+ and VersaBoard) Here we emulate the base configurations of these two boards: MegaCart+ = up to 512K (31 banks at $8000, 1 at $C000) of ROM and 2 x 16K RAM @ $4000 VersaBoard = up to 256K of ROM and 2 x 16K RAM Plus, for the moment, a VersaBoard with POKEY mapped at 0x0450 and support for 144K ROM, since a few demo homebrew programs seems to use this to combine compatibility with XBoarD & XM expansions Note that the VersaBoard can be configured to work with different banking hardware e.g. with SG 9bank games or with SG + RAM (so to allow reproduction of games which could have worked on old carts without sacrifying original carts), but games running on those "standard" variants can be emulated with the standard code from rom.c ;-) TO DO: - investigate whether the POKEY detection routines in homebrew do fail due to emulation issues or not ***********************************************************************************************************/ #include "emu.h" #include "cpuwiz.h" //------------------------------------------------- // constructor //------------------------------------------------- const device_type A78_ROM_VERSABOARD = &device_creator; const device_type A78_ROM_MEGACART = &device_creator; const device_type A78_ROM_P450_VB = &device_creator; a78_versaboard_device::a78_versaboard_device(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, UINT32 clock, const char *shortname, const char *source) : a78_rom_sg_device(mconfig, type, name, tag, owner, clock, shortname, source) { } a78_versaboard_device::a78_versaboard_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : a78_rom_sg_device(mconfig, A78_ROM_VERSABOARD, "Atari 7800 VersaBoard Cart", tag, owner, clock, "a78_versaboard", __FILE__) { } a78_megacart_device::a78_megacart_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : a78_versaboard_device(mconfig, A78_ROM_MEGACART, "Atari 7800 MegaCart+", tag, owner, clock, "a78_megacart", __FILE__) { } a78_rom_p450_vb_device::a78_rom_p450_vb_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : a78_versaboard_device(mconfig, A78_ROM_P450_VB, "Atari 7800 VersaBoard + POKEY @ 0x0450 Cart", tag, owner, clock, "a78_versapokey", __FILE__), m_pokey450(*this, "pokey450") { } void a78_versaboard_device::device_start() { save_item(NAME(m_bank)); save_item(NAME(m_ram_bank)); } void a78_versaboard_device::device_reset() { m_bank = 0; m_ram_bank = 0; } // VersaBoard READ8_MEMBER(a78_versaboard_device::read_40xx) { if (offset < 0x4000) return m_ram[offset + (m_ram_bank * 0x4000)]; else if (offset < 0x8000) return m_rom[(offset & 0x3fff) + (m_bank * 0x4000)]; else return m_rom[(offset & 0x3fff) + (m_bank_mask * 0x4000)]; // last bank } WRITE8_MEMBER(a78_versaboard_device::write_40xx) { if (offset < 0x4000) m_ram[offset + (m_ram_bank * 0x4000)] = data; else if (offset < 0x8000) { // hardware allows up to 256K ROM m_bank = (data & 0x0f) & m_bank_mask; m_ram_bank = BIT(data, 5); } } // MegaCart+ WRITE8_MEMBER(a78_megacart_device::write_40xx) { if (offset < 0x4000) m_ram[offset + (m_ram_bank * 0x4000)] = data; else if (offset < 0x8000) { // hardware allows up to 512K ROM m_bank = (data & 0x1f) & m_bank_mask; m_ram_bank = BIT(data, 5); } } // VersaBoard + POKEY @ 0x0450 static MACHINE_CONFIG_FRAGMENT( a78_pokeyvb ) MCFG_SPEAKER_STANDARD_MONO("addon") MCFG_SOUND_ADD("pokey450", POKEY, XTAL_14_31818MHz/8) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "addon", 1.00) MACHINE_CONFIG_END machine_config_constructor a78_rom_p450_vb_device::device_mconfig_additions() const { return MACHINE_CONFIG_NAME( a78_pokeyvb ); }