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Diffstat (limited to 'src/devices/bus/bbc/internal/overlay.cpp')
-rw-r--r-- | src/devices/bus/bbc/internal/overlay.cpp | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/src/devices/bus/bbc/internal/overlay.cpp b/src/devices/bus/bbc/internal/overlay.cpp new file mode 100644 index 00000000000..c46a280a316 --- /dev/null +++ b/src/devices/bus/bbc/internal/overlay.cpp @@ -0,0 +1,224 @@ +// license:BSD-3-Clause +// copyright-holders:Nigel Barnes +/********************************************************************** + + Vine Micros Romboard '3' (Master OS Overlay Board) + + http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/Vine_MasterOSoverlay.html + +**********************************************************************/ + + +#include "emu.h" +#include "overlay.h" + + +//************************************************************************** +// DEVICE DEFINITIONS +//************************************************************************** + +DEFINE_DEVICE_TYPE(BBC_OVERLAY, bbc_overlay_device, "bbc_overlay", "Vine Micros Romboard '3' (Master OS Overlay)"); + + +//------------------------------------------------- +// INPUT_PORTS( overlay ) +//------------------------------------------------- + +static INPUT_PORTS_START(overlay) + PORT_START("link_rom1") + PORT_CONFNAME(0x1f, 0x0a, "ROM 1") + PORT_CONFSETTING(0x10, "Operating System (reserved)") + PORT_CONFSETTING(0x09, "1770 DFS") + PORT_CONFSETTING(0x0a, "Viewsheet") + PORT_CONFSETTING(0x0b, "Edit") + PORT_CONFSETTING(0x0c, "BASIC") + PORT_CONFSETTING(0x0d, "ADFS") + PORT_CONFSETTING(0x0e, "View (and some GXR)") + PORT_CONFSETTING(0x0f, "Terminal and Operating System (reserved)") + PORT_START("link_rom2") + PORT_CONFNAME(0x1f, 0x0b, "ROM 2") + PORT_CONFSETTING(0x10, "Operating System (reserved)") + PORT_CONFSETTING(0x09, "1770 DFS") + PORT_CONFSETTING(0x0a, "Viewsheet") + PORT_CONFSETTING(0x0b, "Edit") + PORT_CONFSETTING(0x0c, "BASIC") + PORT_CONFSETTING(0x0d, "ADFS") + PORT_CONFSETTING(0x0e, "View (and some GXR)") + PORT_CONFSETTING(0x0f, "Terminal and Operating System (reserved)") + PORT_START("link_rom3") + PORT_CONFNAME(0x1f, 0x0e, "ROM 3") + PORT_CONFSETTING(0x10, "Operating System (reserved)") + PORT_CONFSETTING(0x09, "1770 DFS") + PORT_CONFSETTING(0x0a, "Viewsheet") + PORT_CONFSETTING(0x0b, "Edit") + PORT_CONFSETTING(0x0c, "BASIC") + PORT_CONFSETTING(0x0d, "ADFS") + PORT_CONFSETTING(0x0e, "View (and some GXR)") + PORT_CONFSETTING(0x0f, "Terminal and Operating System (reserved)") +INPUT_PORTS_END + +//------------------------------------------------- +// input_ports - device-specific input ports +//------------------------------------------------- + +ioport_constructor bbc_overlay_device::device_input_ports() const +{ + return INPUT_PORTS_NAME(overlay); +} + +//------------------------------------------------- +// device_add_mconfig - add device configuration +//------------------------------------------------- + +void bbc_overlay_device::device_add_mconfig(machine_config &config) +{ + /* 3 x 16K rom sockets */ + BBC_ROMSLOT16(config, m_rom[0], bbc_rom_devices, nullptr); + BBC_ROMSLOT16(config, m_rom[1], bbc_rom_devices, nullptr); + BBC_ROMSLOT16(config, m_rom[2], bbc_rom_devices, nullptr); +} + + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +//------------------------------------------------- +// bbc_overlay_device - constructor +//------------------------------------------------- + +bbc_overlay_device::bbc_overlay_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) + : device_t(mconfig, BBC_OVERLAY, tag, owner, clock) + , device_bbc_internal_interface(mconfig, *this) + , m_rom(*this, "romslot%u", 0U) + , m_link_rom(*this, "link_rom%u", 1U) +{ +} + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void bbc_overlay_device::device_start() +{ + /* register for save states */ + save_item(NAME(m_romsel)); +} + + +//************************************************************************** +// IMPLEMENTATION +//************************************************************************** + +uint8_t bbc_overlay_device::paged_r(offs_t offset) +{ + uint8_t data = 0xff; + + switch (m_romsel) + { + case 9: case 10: case 11: case 12: case 13: case 14: case 15: + /* overlay banks */ + if (m_link_rom[0]->read() == m_romsel && m_rom[0]->present()) + { + data = m_rom[0]->read(offset); + } + else if (m_link_rom[1]->read() == m_romsel && m_rom[1]->present()) + { + data = m_rom[1]->read(offset); + } + else if (m_link_rom[2]->read() == m_romsel && m_rom[2]->present()) + { + data = m_rom[2]->read(offset); + } + else + { + data = m_region_swr->base()[offset + (m_romsel << 14)]; + } + break; + case 4: case 5: case 6: case 7: + /* motherboard ram selected */ + if (m_mb_rom[m_romsel & 0x0e] && m_mb_rom[m_romsel & 0x0e]->present()) + { + data = m_mb_rom[m_romsel & 0x0e]->read(offset | (m_romsel & 0x01) << 14); + } + else + { + data = m_region_swr->base()[offset + (m_romsel << 14)]; + } + break; + default: + /* motherboard rom sockets */ + if (m_mb_rom[m_romsel] && m_mb_rom[m_romsel]->present()) + { + data = m_mb_rom[m_romsel]->read(offset); + } + else + { + data = m_region_swr->base()[offset + (m_romsel << 14)]; + } + break; + } + + return data; +} + +void bbc_overlay_device::paged_w(offs_t offset, uint8_t data) +{ + switch (m_romsel) + { + case 9: case 10: case 11: case 12: case 13: case 14: case 15: + /* overlay banks */ + if (m_link_rom[0]->read() == m_romsel && m_rom[0]->present()) + { + m_rom[0]->write(offset, data); + } + else if (m_link_rom[1]->read() == m_romsel && m_rom[1]->present()) + { + m_rom[1]->write(offset, data); + } + else if (m_link_rom[2]->read() == m_romsel && m_rom[2]->present()) + { + m_rom[2]->write(offset, data); + } + break; + case 4: case 5: case 6: case 7: + /* motherboard ram selected */ + if (m_mb_rom[m_romsel & 0x0e]) + { + m_mb_rom[m_romsel & 0x0e]->write(offset | (m_romsel & 0x01) << 14, data); + } + break; + default: + /* motherboard rom sockets */ + if (m_mb_rom[m_romsel]) + { + m_mb_rom[m_romsel]->write(offset, data); + } + break; + } +} + + +uint8_t bbc_overlay_device::mos_r(offs_t offset) +{ + uint8_t data = 0xff; + + if (m_link_rom[0]->read() == 0x10 && m_rom[0]->present()) + { + data = m_rom[0]->read(offset); + } + else if (m_link_rom[1]->read() == 0x10 && m_rom[1]->present()) + { + data = m_rom[1]->read(offset); + } + else if (m_link_rom[2]->read() == 0x10 && m_rom[2]->present()) + { + data = m_rom[2]->read(offset); + } + else + { + data = m_region_mos->base()[offset]; + } + + return data; +} |