CanonWordProcessor.cc

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