OXYGENHUB
◆ main openmsx / src / memory / FraelSwitchableROM.cc
1.9 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#include "FraelSwitchableROM.hh"
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#include "serialize.hh"
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/*
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 * Information as reverse engineered by FRS:
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 *
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 * Curiously, the machine works without the boot-logo+firmware ROM, because the
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 * MainBIOS checks for its presence. If it's not there, it just skips the logo and
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 * the menu. Maybe they were planning a cheaper version without that ROM.
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 *
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 * The boot-logo+firmware ROM is selected by the bit7 of the I/O port 90h. This is
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 * the same port that has the strobe bit (bit-1) in normal MSX computers. Besides
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 * the extra bit, the rest of the printer port seems to be pretty ordinary.
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 *
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 * Bit7=0: Select Frael MainBIOS ROM on slot-0
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 * Bit7=1: Select the boot-logo+firmware ROM on slot-0
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 */
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namespace openmsx {
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FraelSwitchableROM::FraelSwitchableROM(DeviceConfig& config)
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	: MSXDevice(config)
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	, basicBiosRom(getName() + " BASIC/BIOS", "rom", config, "basicbios")
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	, firmwareRom (getName() + " firmware"  , "rom", config, "firmware" )
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{
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	reset(EmuTime::dummy());
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}
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void FraelSwitchableROM::writeIO(uint16_t /*port*/, byte value, EmuTime /*time*/)
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{
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	bool newValue = value & 0x80;
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	if (newValue != firmwareSelected) {
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		firmwareSelected = newValue;
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		invalidateDeviceRCache();
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	}
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}
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void FraelSwitchableROM::reset(EmuTime /*time*/)
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{
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	firmwareSelected = false;
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	invalidateDeviceRCache();
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}
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byte FraelSwitchableROM::readMem(uint16_t address, EmuTime /*time*/)
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{
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	return *getReadCacheLine(address);
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}
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const byte* FraelSwitchableROM::getReadCacheLine(uint16_t start) const
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{
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	return firmwareSelected ? &firmwareRom[start & (firmwareRom.size() - 1)] :
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		&basicBiosRom[start & (basicBiosRom.size() - 1)];
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}
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template<typename Archive>
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void FraelSwitchableROM::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<MSXDevice>(*this);
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	ar.serialize("firmwareSelected", firmwareSelected);
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}
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INSTANTIATE_SERIALIZE_METHODS(FraelSwitchableROM);
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REGISTER_MSXDEVICE(FraelSwitchableROM, "FraelSwitchableROM");
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} // namespace openmsx