ChakkariCopy.cc

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#include "ChakkariCopy.hh"
#include "CliComm.hh"
#include "serialize.hh"
 
// The cartridge has 2 buttons with 2 LEDs, marked PAUSE and COPY. It also has
// a toggle switch with the options COPY and RAM. Setting this toggle to RAM
// makes the cartridge a 16kB RAM expansion.
//
// The following information is provided by Rudolf Lechleitner, who devised it
// together with Enrico Barbisan.
//
// ----------------------------------------------------------------------------
//
// The memory layout:
//
// +--------------------------------------------+
// | 0000-3FFF: 16 KB RAM in COPY mode          |
// | Page 0: available in COPY mode only        |
// | can be toggled to read-only                |
// +--------------------------------------------+
// | 4000-5FFF: 8KB ROM code                    |
// | Page 1: +                                  |
// | 6000-67FF: 2KB internal RAM                |
// +--------------------------------------------+
//
// The shown 16KB RAM in page 0 are only available in COPY mode, but can be
// toggled to read-only. The location of the RAM in RAM mode is unknown.
//
// The memory at 6800-7FFF is unused by the cartridge.
//
// Internal handling: during cartridge initialisation Chakkari Copy copies the
// contents of BIOS page 0 into its own RAM and patches some entries to
// capture the input of PAUSE and COPY buttons of the cartridge. Afterwards the
// patched memory is set to read-only.
// PAUSE and COPY itself are processed by the routines in the ROM. In case the
// page 0 is (for any reason) switched to the original MSX-BIOS the cartridge
// buttons are no longer working. In this case CALL SCHANGE switches the BIOS
// to the patched version again.
//
// In case a program switches screen modes in a way that prevents Chakkari Copy
// from detecting the correct parameters Chakkari Copy can be started by
// keeping the COPY button pressed. In this case the screen-mode autodetect
// will be skipped and the parameters can be entered manually.
// This appears to be an undocumented feature, confirmed by typos and a very
// rudimentary screen handling.
//
// In case the printer is not ready or not available the printing can be
// aborted by pressing Ctrl+Stop.
//
// The Chakkari Copy cartridge has one register, which controls its complete
// behavior. This register is available at MSX port &H7F.
//
// READ only:
//
// +-----------------------------------------+
// |  1  |  1  |  1  |  1  |  1  | PSE | CPY |
// +-----+-----+-----+-----+-----+-----+-----+
// CPY: 0 = Copy button pressed, 1 = Copy button released
// PSE: 0 = Pause button pressed, 1 = Pause button released
//
// WRITE only:
//
// +-----+-----+-----+-----+-----+-----+-----+
// |  1  |  1  |  1  |  1  | RAM | PSE | CPY |
// +-----+-----+-----+-----+-----+-----+-----+
// CPY: 0 = Copy LED on, 1 = Copy LED off
// PSE: 0 = Pause LED on, 1 = Pause LED off
// RAM: 0 = Page 0 in RAM mode, 1 = Page 0 in ROM mode (applies to COPY mode only)
//
// ----------------------------------------------------------------------------
 
// The RAM mode has now been implemented to switch the RAM to page 1. This
// doesn't seem to be the most logical, but it's closest to the output of
// MSXMEM2. It could still be useful for 32kB machines.
//
// The work RAM has been mirrored in the 0x6000-0x8000 area to match the output
// of MSXMEM2.BAS which was run on a machine with the real cartridge inserted.
// It showed 'R' on page 1 for both COPY and RAM mode. The only thing that
// doesn't match yet is that it also showed 'R' in page 0 for COPY mode for
// subslots 0 and 1. The latter is unexplained so far.
 
namespace openmsx {
 
ChakkariCopy::ChakkariCopy(const DeviceConfig& config)
        : MSXDevice(config)
        , biosRam(config, getName() + " BIOS RAM", "Chakkari Copy BIOS RAM", 0x4000)
        , workRam(config, getName() + " work RAM", "Chakkari Copy work RAM", 0x0800)
        , rom(getName() + " ROM", "rom", config)
        , pauseButtonPressedSetting(getCommandController(),
                getName() + " PAUSE button pressed",
                "controls the PAUSE button state", false, Setting::DONT_SAVE)
        , copyButtonPressedSetting(getCommandController(),
                getName() + " COPY button pressed",
                "controls the COPY button state", false, Setting::DONT_SAVE)
        , modeSetting(getCommandController(), getName() + " mode",
                "Sets mode of the cartridge: in COPY mode you can hardcopy MSX1 screens, "
                "in RAM mode you just have a 16kB RAM expansion", ChakkariCopy::COPY,
                EnumSetting<ChakkariCopy::Mode>::Map{
                        {"COPY", ChakkariCopy::COPY}, {"RAM", ChakkariCopy::RAM}})
        , reg(0xFF) // avoid UMR in initial writeIO()
{
        reset(getCurrentTime());
        modeSetting.attach(*this);
}
 
ChakkariCopy::~ChakkariCopy()
{
        modeSetting.detach(*this);
}
 
void ChakkariCopy::reset(EmuTime::param time)
{
        writeIO(0, 0xFF, time);
}
 
void ChakkariCopy::writeIO(word /*port*/, byte value, EmuTime::param /*time*/)
{
        byte diff = reg ^ value;
        reg = value;
 
        if (diff & 0x01) {
                getCliComm().printInfo(getName(), " COPY LED ",
                        (((value & 1) == 0x01) ? "OFF" : "ON"));
        }
        if (diff & 0x02) {
                getCliComm().printInfo(getName(), " PAUSE LED ",
                        (((value & 2) == 0x02) ? "OFF" : "ON"));
        }
        if (diff & 0x04) {
                if (modeSetting.getEnum() == COPY) {
                        // page 0 toggles writable/read-only
                        invalidateDeviceRWCache(0x0000, 0x4000);
                }
        }
}
 
byte ChakkariCopy::readIO(word port, EmuTime::param time)
{
        return peekIO(port, time);
}
 
byte ChakkariCopy::peekIO(word /*port*/, EmuTime::param /*time*/) const
{
        byte retVal = 0xFF;
        if (copyButtonPressedSetting .getBoolean()) retVal &= ~0x01;
        if (pauseButtonPressedSetting.getBoolean()) retVal &= ~0x02;
        return retVal;
}
 
byte ChakkariCopy::readMem(word address, EmuTime::param time)
{
        return peekMem(address, time);
}
 
byte ChakkariCopy::peekMem(word address, EmuTime::param /*time*/) const
{
        return *getReadCacheLine(address);
}
 
const byte* ChakkariCopy::getReadCacheLine(word address) const
{
        if (modeSetting.getEnum() == COPY) {
                // page 0
                if (address < 0x4000) {
                        return &biosRam[address];
                }
                // page 1
                if ((0x4000 <= address) && (address < 0x6000)) {
                        return &rom[address & 0x1FFF];
                }
                // the work RAM is mirrored in 0x6000-0x8000, see above
                if ((0x6000 <= address) && (address < 0x8000)) {
                        return &workRam[address & 0x07FF];
                }
        } else {
                // page 1 RAM mode
                if ((0x4000 <= address) && (address < 0x8000)) {
                        return &biosRam[address & 0x3FFF];
                }
        }
        return unmappedRead;
}
 
void ChakkariCopy::writeMem(word address, byte value, EmuTime::param /*time*/)
{
        *getWriteCacheLine(address) = value;
}
 
byte* ChakkariCopy::getWriteCacheLine(word address) const
{
        if (modeSetting.getEnum() == COPY) {
                // page 0
                if ((address < 0x4000) && ((reg & 0x04) == 0)) {
                        return const_cast<byte*>(&biosRam[address & 0x3FFF]);
                }
                // page 1
                // the work RAM is mirrored in 0x6000-0x8000, see above
                if ((0x6000 <= address) && (address < 0x8000)) {
                        return const_cast<byte*>(&workRam[address & 0x07FF]);
                }
        } else {
                // page 1 RAM mode
                if ((0x4000 <= address) && (address < 0x8000)) {
                        return const_cast<byte*>(&biosRam[address & 0x3FFF]);
                }
        }
        return unmappedWrite;
}
 
void ChakkariCopy::update(const Setting& /*setting*/) noexcept
{
        // switch COPY <-> RAM mode, memory layout changes
        invalidateDeviceRWCache();
}
 
template<typename Archive>
void ChakkariCopy::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<MSXDevice>(*this);
        ar.serialize("biosRam", biosRam,
                     "workRam", workRam,
                     "reg", reg);
        if (ar.isLoader()) {
                writeIO(0, reg, getCurrentTime());
        }
 
}
INSTANTIATE_SERIALIZE_METHODS(ChakkariCopy);
REGISTER_MSXDEVICE(ChakkariCopy, "ChakkariCopy");
 
} // namespace openmsx