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// license:BSD-3-Clause
// copyright-holders:Curt Coder
/**********************************************************************
Epyx Fast Load cartridge emulation
**********************************************************************/
#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, std::string 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), m_exrom_timer(nullptr)
{
}
//-------------------------------------------------
// 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);
}
}
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