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-rw-r--r--src/devices/bus/bbc/internal/overlay.cpp224
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
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+++ b/src/devices/bus/bbc/internal/overlay.cpp
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+// 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;
+}