diff options
Diffstat (limited to 'src/devices/bus/bbc/internal/weromram.cpp')
-rw-r--r-- | src/devices/bus/bbc/internal/weromram.cpp | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/src/devices/bus/bbc/internal/weromram.cpp b/src/devices/bus/bbc/internal/weromram.cpp new file mode 100644 index 00000000000..ceb8be3e270 --- /dev/null +++ b/src/devices/bus/bbc/internal/weromram.cpp @@ -0,0 +1,133 @@ +// license:BSD-3-Clause +// copyright-holders:Nigel Barnes +/********************************************************************** + + Watford Electronics ROM/RAM Board + + http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/WE_RAMROMBoard.html + +**********************************************************************/ + + +#include "emu.h" +#include "weromram.h" + + +//************************************************************************** +// DEVICE DEFINITIONS +//************************************************************************** + +DEFINE_DEVICE_TYPE(BBC_WEROMRAM, bbc_weromram_device, "bbc_weromram", "Watford Electronics ROM/RAM Board"); + + +//------------------------------------------------- +// device_add_mconfig - add device configuration +//------------------------------------------------- + +void bbc_weromram_device::device_add_mconfig(machine_config &config) +{ + /* 3 rom sockets, 64K dynamic ram, 16K static ram (battery backed) */ + BBC_ROMSLOT16(config, m_rom[0], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[1], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[2], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[3], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[4], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[5], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[6], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[7], bbc_rom_devices, "ram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[12], bbc_rom_devices, nullptr); + BBC_ROMSLOT16(config, m_rom[13], bbc_rom_devices, nullptr); + BBC_ROMSLOT16(config, m_rom[14], bbc_rom_devices, "nvram").set_fixed_ram(true); + BBC_ROMSLOT16(config, m_rom[15], bbc_rom_devices, nullptr); +} + + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +//------------------------------------------------- +// bbc_weromram_device - constructor +//------------------------------------------------- + +bbc_weromram_device::bbc_weromram_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) + : device_t(mconfig, BBC_WEROMRAM, tag, owner, clock) + , device_bbc_internal_interface(mconfig, *this) + , m_rom(*this, "romslot%u", 0U) +{ +} + + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void bbc_weromram_device::device_start() +{ + /* move internal roms to board */ + memmove(m_region_swr->base() + 0x2c000, m_region_swr->base(), 0xc000); + memmove(m_region_swr->base() + 0x3c000, m_region_swr->base() + 0xc000, 0x4000); + memset(m_region_swr->base(), 0xff, 0x10000); + + /* register for save states */ + save_item(NAME(m_romsel)); + save_item(NAME(m_ramsel)); +} + + +//************************************************************************** +// IMPLEMENTATION +//************************************************************************** + +uint8_t bbc_weromram_device::paged_r(offs_t offset) +{ + uint8_t data = 0xff; + + switch (m_romsel) + { + case 8: case 9: case 10: case 11: + /* motherboard rom sockets 0-3 are re-assigned to 8-11 */ + if (m_mb_rom[m_romsel & 0x03] && m_mb_rom[m_romsel & 0x03]->present()) + { + data = m_mb_rom[m_romsel & 0x03]->read(offset); + } + else + { + data = m_region_swr->base()[offset + (m_romsel << 14) - 0x20000]; + } + break; + default: + /* expansion board sockets */ + if (m_rom[m_romsel] && m_rom[m_romsel]->present()) + { + data = m_rom[m_romsel]->read(offset); + } + else + { + data = m_region_swr->base()[offset + (m_romsel << 14)]; + } + break; + } + + return data; +} + +void bbc_weromram_device::paged_w(offs_t offset, uint8_t data) +{ + switch (m_romsel) + { + case 8: case 9: case 10: case 11: + /* motherboard rom sockets 0-3 are re-assigned to 8-11 */ + if (m_mb_rom[m_romsel & 0x03]) + { + m_mb_rom[m_romsel & 0x03]->write(offset, data); + } + break; + } + + /* expansion board sockets */ + if (m_rom[m_ramsel]) + { + m_rom[m_ramsel]->write(offset, data); + } +} |