diff options
Diffstat (limited to 'src/mess/machine/c64/epyx_fast_load.c')
-rw-r--r-- | src/mess/machine/c64/epyx_fast_load.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/src/mess/machine/c64/epyx_fast_load.c b/src/mess/machine/c64/epyx_fast_load.c new file mode 100644 index 00000000000..899056abce7 --- /dev/null +++ b/src/mess/machine/c64/epyx_fast_load.c @@ -0,0 +1,117 @@ +/********************************************************************** + + Epyx Fast Load cartridge emulation + + Copyright MESS Team. + Visit http://mamedev.org for licensing and usage restrictions. + +**********************************************************************/ + +#include "epyx_fast_load.h" + + + +//************************************************************************** +// MACROS/CONSTANTS +//************************************************************************** + +// t = R*C = 3.3K * 0.47uF * 40% Vtr = 792.2905424610516 usec +// (3.3K pull-up on the EXROM line inside the C64, PLA Vih min = 2.0V = 40% of 5.0V) +#define TIMER_PERIOD 792 + + + +//************************************************************************** +// DEVICE DEFINITIONS +//************************************************************************** + +const device_type C64_EPYX_FAST_LOAD = &device_creator<c64_epyx_fast_load_cartridge_device>; + + + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +//------------------------------------------------- +// c64_epyx_fast_load_cartridge_device - constructor +//------------------------------------------------- + +c64_epyx_fast_load_cartridge_device::c64_epyx_fast_load_cartridge_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : + device_t(mconfig, C64_EPYX_FAST_LOAD, "C64 Epyx Fast Load cartridge", tag, owner, clock, "c64_epyx_fast_load", __FILE__), + device_c64_expansion_card_interface(mconfig, *this) +{ +} + + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void c64_epyx_fast_load_cartridge_device::device_start() +{ + // allocate timer + m_exrom_timer = timer_alloc(); +} + + +//------------------------------------------------- +// device_reset - device-specific reset +//------------------------------------------------- + +void c64_epyx_fast_load_cartridge_device::device_reset() +{ + m_exrom = 0; + m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0); +} + + +//------------------------------------------------- +// device_timer - handler timer events +//------------------------------------------------- + +void c64_epyx_fast_load_cartridge_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) +{ + m_exrom = 1; +} + + +//------------------------------------------------- +// c64_cd_r - cartridge data read +//------------------------------------------------- + +UINT8 c64_epyx_fast_load_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 (!roml) + { + m_exrom = 0; + m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0); + + data = m_roml[offset & 0x1fff]; + } + else if (!io1) + { + m_exrom = 0; + m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0); + } + else if (!io2) + { + data = m_roml[offset & 0x1fff]; + } + + return data; +} + + +//------------------------------------------------- +// c64_cd_w - cartridge data write +//------------------------------------------------- + +void c64_epyx_fast_load_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 (!io1) + { + m_exrom = 0; + m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0); + } +} |