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// license:BSD-3-Clause
// copyright-holders:Nigel Barnes
/***************************************************************************
Solidisk Mega 256 cartridge emulation
http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/Solidisk_Mega256.html
***************************************************************************/
#include "emu.h"
#include "mega256.h"
//**************************************************************************
// DEVICE DEFINITIONS
//**************************************************************************
DEFINE_DEVICE_TYPE(BBC_MEGA256, bbc_mega256_device, "bbc_mega256", "Solidisk Mega 256 cartridge")
//**************************************************************************
// LIVE DEVICE
//**************************************************************************
//-------------------------------------------------
// bbc_mega256_device - constructor
//-------------------------------------------------
bbc_mega256_device::bbc_mega256_device(const machine_config &mconfig, const char *tag, device_t *owner, const XTAL &clock)
: device_t(mconfig, BBC_MEGA256, tag, owner, clock)
, device_bbc_cart_interface(mconfig, *this)
, m_page(0)
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void bbc_mega256_device::device_start()
{
// register for save states
save_item(NAME(m_page));
}
//-------------------------------------------------
// device_reset - device-specific reset
//-------------------------------------------------
void bbc_mega256_device::device_reset()
{
m_page = 0x00;
}
//-------------------------------------------------
// read - cartridge data read
//-------------------------------------------------
uint8_t bbc_mega256_device::read(offs_t offset, int infc, int infd, int romqa, int oe, int oe2)
{
uint8_t data = 0xff;
if (oe)
{
if (romqa)
{
data = m_rom[offset & 0x1fff];
}
else
{
data = m_ram[(offset & 0x3fff) | (m_page << 14)];
}
}
return data;
}
//-------------------------------------------------
// write - cartridge data write
//-------------------------------------------------
void bbc_mega256_device::write(offs_t offset, uint8_t data, int infc, int infd, int romqa, int oe, int oe2)
{
if (oe)
{
if (romqa)
{
// Not known whether this latch is fully decoded.
if (offset == 0x3fff) m_page = data & 0x0f;
}
else
{
m_ram[(offset & 0x3fff) | (m_page << 14)] = data;
}
}
}
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