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Diffstat (limited to 'src/mess/machine/c64/dqbb.c')
-rw-r--r-- | src/mess/machine/c64/dqbb.c | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/src/mess/machine/c64/dqbb.c b/src/mess/machine/c64/dqbb.c new file mode 100644 index 00000000000..1b27391231d --- /dev/null +++ b/src/mess/machine/c64/dqbb.c @@ -0,0 +1,122 @@ +/********************************************************************** + + Brown Boxes Double Quick Brown Box emulation + + Copyright MESS Team. + Visit http://mamedev.org for licensing and usage restrictions. + +**********************************************************************/ + +/* + + TODO: + + - 64/128 mode switch + - dump of the initial NVRAM contents + +*/ + +#include "dqbb.h" + + + +//************************************************************************** +// DEVICE DEFINITIONS +//************************************************************************** + +const device_type C64_DQBB = &device_creator<c64_dqbb_cartridge_device>; + + + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +//------------------------------------------------- +// c64_dqbb_cartridge_device - constructor +//------------------------------------------------- + +c64_dqbb_cartridge_device::c64_dqbb_cartridge_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : + device_t(mconfig, C64_DQBB, "C64 Double Quick Brown Box cartridge", tag, owner, clock, "c64_dqbb", __FILE__), + device_c64_expansion_card_interface(mconfig, *this), + device_nvram_interface(mconfig, *this) +{ +} + + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void c64_dqbb_cartridge_device::device_start() +{ + // allocate memory + c64_nvram_pointer(machine(), 0x4000); + + // state saving + save_item(NAME(m_cs)); + save_item(NAME(m_we)); +} + + +//------------------------------------------------- +// device_reset - device-specific reset +//------------------------------------------------- + +void c64_dqbb_cartridge_device::device_reset() +{ + m_exrom = 0; // TODO 1 in 128 mode + m_game = 1; + m_cs = 0; + m_we = 0; +} + + +//------------------------------------------------- +// c64_cd_r - cartridge data read +//------------------------------------------------- + +UINT8 c64_dqbb_cartridge_device::c64_cd_r(address_space &space, offs_t offset, UINT8 data, int sphi2, int ba, int roml, int romh, int io1, int io2) +{ + if (!m_cs && (!roml || !romh)) + { + data = m_nvram[offset & 0x3fff]; + } + + return data; +} + + +//------------------------------------------------- +// c64_cd_w - cartridge data write +//------------------------------------------------- + +void c64_dqbb_cartridge_device::c64_cd_w(address_space &space, offs_t offset, UINT8 data, int sphi2, int ba, int roml, int romh, int io1, int io2) +{ + if (!m_cs && m_we && (offset >= 0x8000 && offset < 0xc000)) + { + m_nvram[offset & 0x3fff] = data; + } + else if (!io1) + { + /* + + bit description + + 0 + 1 + 2 GAME + 3 + 4 WE + 5 + 6 EXROM + 7 _CS + + */ + + m_exrom = !BIT(data, 6); + m_game = !BIT(data, 2); + m_we = BIT(data, 4); + m_cs = BIT(data, 7); + } +} |