diff options
Diffstat (limited to 'src/devices/bus/bbc/internal/we32kram.cpp')
-rw-r--r-- | src/devices/bus/bbc/internal/we32kram.cpp | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/src/devices/bus/bbc/internal/we32kram.cpp b/src/devices/bus/bbc/internal/we32kram.cpp new file mode 100644 index 00000000000..4e0e084e655 --- /dev/null +++ b/src/devices/bus/bbc/internal/we32kram.cpp @@ -0,0 +1,146 @@ +// license:BSD-3-Clause +// copyright-holders:Nigel Barnes +/********************************************************************** + + Watford Electronics 32K RAM card + + http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/WE_32KRAMcard.html + +**********************************************************************/ + + +#include "emu.h" +#include "we32kram.h" + + +//************************************************************************** +// DEVICE DEFINITIONS +//************************************************************************** + +DEFINE_DEVICE_TYPE(BBC_WE32KRAM, bbc_we32kram_device, "bbc_we32kram", "Watford Electronics 32K Shadow RAM"); + + +//------------------------------------------------- +// ROM( we32kram ) +//------------------------------------------------- + +ROM_START(we32kram) + ROM_REGION(0x4000, "exp_rom", 0) + ROM_SYSTEM_BIOS(0, "240", "v2.40") + ROMX_LOAD("we32kram_v2.40.rom", 0x0000, 0x2000, CRC(db9c3a1a) SHA1(0a5efb084eb1ae353b9c79c026e9e26cd7695293), ROM_BIOS(0)) + ROM_SYSTEM_BIOS(1, "220", "v2.20") + ROMX_LOAD("we32kram_v2.20.rom", 0x0000, 0x2000, CRC(bc7124e0) SHA1(7f8536576de449916cd77488e94775ed438c5c6c), ROM_BIOS(1)) + ROM_SYSTEM_BIOS(2, "200", "v2.00") + ROMX_LOAD("we32kram_v2.00.rom", 0x0000, 0x2000, CRC(1eff9b23) SHA1(98a3084b20c92427c2e9def58ade96f42659e20a), ROM_BIOS(2)) + ROM_SYSTEM_BIOS(3, "106", "v1.06") + ROMX_LOAD("we32kram_v1.06.rom", 0x0000, 0x2000, CRC(b9749390) SHA1(210f6162d634fca8d75197d4f64d9b50abc01e1e), ROM_BIOS(3)) + ROM_SYSTEM_BIOS(4, "100", "v1.00") + ROMX_LOAD("we32kram_v1.00.rom", 0x0000, 0x2000, CRC(7962b5db) SHA1(1b59a3354cfc704ad8aa60b0ed16e4cd2d815031), ROM_BIOS(4)) +ROM_END + +//------------------------------------------------- +// rom_region - device-specific ROM region +//------------------------------------------------- + +const tiny_rom_entry *bbc_we32kram_device::device_rom_region() const +{ + return ROM_NAME(we32kram); +} + + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +//------------------------------------------------- +// bbc_we32kram_device - constructor +//------------------------------------------------- + +bbc_we32kram_device::bbc_we32kram_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) + : device_t(mconfig, BBC_WE32KRAM, tag, owner, clock) + , device_bbc_internal_interface(mconfig, *this) +{ +} + + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void bbc_we32kram_device::device_start() +{ + m_shadow = 2; + m_ram = std::make_unique<uint8_t[]>(0x8000); + + /* register for save states */ + save_item(NAME(m_shadow)); + save_pointer(NAME(m_ram), 0x8000); +} + +//------------------------------------------------- +// device_reset - device-specific reset +//------------------------------------------------- + +void bbc_we32kram_device::device_reset() +{ + address_space &program = m_maincpu->space(AS_PROGRAM); + + program.install_write_handler(0xfffc, 0xffff, write8sm_delegate(*this, FUNC(bbc_we32kram_device::control_w))); +} + +//************************************************************************** +// IMPLEMENTATION +//************************************************************************** + +void bbc_we32kram_device::control_w(offs_t offset, uint8_t data) +{ + m_shadow = offset; +} + +uint8_t bbc_we32kram_device::ram_r(offs_t offset) +{ + uint8_t data = 0xff; + + switch (m_shadow) + { + case 0: + /* &fffc - swap whole memory */ + data = m_ram[offset]; + break; + case 2: + /* &fffe - select BBC ram */ + data = m_mb_ram->pointer()[offset]; + break; + case 3: + /* &ffff - select Watford ram */ + if (offset >= 0x3000) + data = m_ram[offset]; + else + data = m_mb_ram->pointer()[offset]; + break; + } + + return data; +} + +void bbc_we32kram_device::ram_w(offs_t offset, uint8_t data) +{ + switch (m_shadow) + { + case 0: + /* &fffc - swap whole memory */ + m_ram[offset] = data; + break; + case 2: + /* &fffe - select BBC ram */ + m_mb_ram->pointer()[offset] = data; + break; + case 3: + /* &ffff - select Watford ram */ + if (offset >= 0x3000) + m_ram[offset] = data; + else + m_mb_ram->pointer()[offset] = data; + break; + } +} |