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◆ main openmsx / src / memory / CanonWordProcessor.cc
3.3 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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// EC701 - Japanese Word Processor Unit (Konami)
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// Reverse engineered by Albert Beevendorp.
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// Probably identical to Canon VWU-100.
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//
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// Select register in range 0xbff8-0xbfff (0xbfff used by software).
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// This select the memory visible in area 0x4000-0x7fff.
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// The value written here is inverted, then:
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//   bit 5-3 = chip select:
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//        000: program ROM (lower 16 kB)
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//        100: dictionary ROM   0-128 kB
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//        101: dictionary ROM 128-256 kB
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//        110: dictionary ROM 256-384 kB
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//     others: not mapped (reads as 0xc0)
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//   bit 2-0 = block select within dictionary ROM
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//
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// Area 0x8000-0xbff7 reads from program ROM (upper 16 kB)
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//
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// Also check the electrical schema on:
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//   http://d4.princess.ne.jp/msx/other/ec700/index.htm
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#include "CanonWordProcessor.hh"
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#include "CacheLine.hh"
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#include "MSXException.hh"
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#include "serialize.hh"
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namespace openmsx {
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CanonWordProcessor::CanonWordProcessor(DeviceConfig& config)
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	: MSXDevice(config)
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	, programRom   (strCat(config.getAttributeValue("id"), "_program"),    "rom", config, "program")
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	, dictionaryRom(strCat(config.getAttributeValue("id"), "_dictionary"), "rom", config, "dictionary")
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{
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	if (programRom.size() != 32*1024) {
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		throw MSXException("Program ROM must be 32kB.");
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	}
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	if (dictionaryRom.size() != 3*128*1024) {
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		throw MSXException("Dictionary ROM must be 3x 128kB.");
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	}
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	reset(EmuTime::dummy());
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}
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void CanonWordProcessor::reset(EmuTime time)
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{
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	writeMem(0xbfff, 0xff, time);
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}
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byte CanonWordProcessor::readMem(uint16_t address, EmuTime time)
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{
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	return peekMem(address, time);
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}
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byte CanonWordProcessor::peekMem(uint16_t address, EmuTime /*time*/) const
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{
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	if ((0xbff8 <= address) && (address <= 0xbfff)) {
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		return 0xc0; // select area, does NOT read from ROM
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	} else {
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		if (const auto* a = readHelper(address)) {
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			return *a;
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		}
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		return 0xc0;
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	}
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}
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const byte* CanonWordProcessor::getReadCacheLine(uint16_t start) const
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{
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	if ((start & CacheLine::HIGH) == (0xbfff & CacheLine::HIGH)) {
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		return nullptr; // select register
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	} else {
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		return readHelper(start);
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	}
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}
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const byte* CanonWordProcessor::readHelper(uint16_t address) const
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{
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	if ((0x4000 <= address) && (address <= 0x7fff)) {
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		auto chip = (select & 0b00'111'000) >> 3;
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		auto bank = (select & 0b00'011'111);
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		address &= 0x3fff;
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		switch (chip) {
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		case 0b000:
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			return &programRom[address];
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		case 0b100: case 0b101: case 0b110:
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			return &dictionaryRom[0x4000 * bank + address];
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		// note: according to the schematic on
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		// http://d4.princess.ne.jp/msx/other/ec700/index.htm, the
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		// outputs of IC5's 3-to-8 decoder for '001' '010' '011' and
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		// '111' are unconnected
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		}
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		return nullptr; // unmapped, but reads as 0xc0 instead of 0xff ??
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	} else {
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		// 0x8000 - 0xbfff
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		return &programRom[0x4000 + (address & 0x3fff)];
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	}
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}
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void CanonWordProcessor::writeMem(uint16_t address, byte value, EmuTime /*time*/)
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{
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	if ((0xbff8 <= address) && (address <= 0xbfff)) {
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		select = ~value; // invert !!
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		invalidateDeviceRCache(0x4000, 0x4000);
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	}
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}
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byte* CanonWordProcessor::getWriteCacheLine(uint16_t /*start*/)
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{
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	return nullptr;
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}
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template<typename Archive>
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void CanonWordProcessor::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<MSXDevice>(*this);
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	ar.serialize("select", select);
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}
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INSTANTIATE_SERIALIZE_METHODS(CanonWordProcessor);
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REGISTER_MSXDEVICE(CanonWordProcessor, "CanonWordProcessor");
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} // namespace openmsx