// license:BSD-3-Clause // copyright-holders:Nigel Barnes /********************************************************************** Raven-20 RAM expansion board TODO: - Verify behaviour of RAVEN-20 1.00, seems buggy or incomplete emulation. - FAST mode (*FRON) is not understood. **********************************************************************/ #include "emu.h" #include "raven20.h" //************************************************************************** // DEVICE DEFINITIONS //************************************************************************** DEFINE_DEVICE_TYPE(BBC_RAVEN20, bbc_raven20_device, "bbc_raven20", "Raven-20 RAM expansion") //------------------------------------------------- // ROM( raven20 ) //------------------------------------------------- ROM_START(raven20) ROM_REGION(0x2000, "exp_rom", 0) ROM_SYSTEM_BIOS(0, "106", "Raven-20 1.06") ROMX_LOAD("raven20_1.06.rom", 0x0000, 0x2000, CRC(7efb0ab3) SHA1(d395199ef8f51579fe74e3d7d8dab1de6e0b30e2), ROM_BIOS(0)) ROM_SYSTEM_BIOS(1, "100", "Raven-20 1.00") ROMX_LOAD("raven20_1.00.rom", 0x0000, 0x2000, CRC(e8c8f9d5) SHA1(e4f2acc07969e10c082355c82d8d1cbc1c08ee2e), ROM_BIOS(1)) ROM_END //------------------------------------------------- // rom_region - device-specific ROM region //------------------------------------------------- const tiny_rom_entry *bbc_raven20_device::device_rom_region() const { return ROM_NAME( raven20 ); } //************************************************************************** // LIVE DEVICE //************************************************************************** //------------------------------------------------- // bbc_raven20_device - constructor //------------------------------------------------- bbc_raven20_device::bbc_raven20_device(const machine_config &mconfig, const char *tag, device_t *owner, const XTAL &clock) : device_t(mconfig, BBC_RAVEN20, tag, owner, clock) , device_bbc_internal_interface(mconfig, *this) { } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void bbc_raven20_device::device_start() { address_space &program = m_maincpu->space(AS_PROGRAM); program.install_write_handler(0xd000, 0xd000, write8sm_delegate(*this, FUNC(bbc_raven20_device::enable_w))); program.install_write_handler(0xc000, 0xc000, write8sm_delegate(*this, FUNC(bbc_raven20_device::disable_w))); m_shadow = false; m_ram = std::make_unique(0x5000); /* register for save states */ save_item(NAME(m_shadow)); save_pointer(NAME(m_ram), 0x5000); } //************************************************************************** // IMPLEMENTATION //************************************************************************** void bbc_raven20_device::enable_w(offs_t offset, uint8_t data) { m_shadow = true; } void bbc_raven20_device::disable_w(offs_t offset, uint8_t data) { m_shadow = false; } uint8_t bbc_raven20_device::ram_r(offs_t offset) { uint8_t data = 0xff; if (m_shadow && offset >= 0x3000) data = m_ram[offset - 0x3000]; else data = m_mb_ram->pointer()[offset]; return data; } void bbc_raven20_device::ram_w(offs_t offset, uint8_t data) { if (m_shadow && offset >= 0x3000) m_ram[offset - 0x3000] = data; else m_mb_ram->pointer()[offset] = data; }