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diff --git a/src/devices/bus/bbc/1mhzbus/cc500.cpp b/src/devices/bus/bbc/1mhzbus/cc500.cpp
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+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/**********************************************************************
+
+ Colour Card 500 - CTS Recognition
+
+ The CTS Palette is a 1 MHz bus device and it can be used to convert the 8
+ colours available on the BBC into any 8 colours from a range of 4096.
+
+ Programming the hardware directly
+ ---------------------------------
+ The hardware consists of 3 banks of very fast RAM (for red, green and blue
+ levels) and a 6522 versatile interface adaptor.
+
+ The memory map is as follows:
+
+ 6522 VIA &FC90 to &FC9F
+
+ RED BANK &FCA0 to &FCA7
+ GREEN BANK &FCA8 to &FCAF
+ BLUE BANK &FCB0 to &FCB8
+
+ There are 8 bytes in each bank, one for each actual colour. The physical
+ colour for logical colour L is stored at &FCA0+L, &FCA8+L and &FCB0+L.
+
+ For example, to reprogram actual colour 1 to brown, 10 would be stored in
+ &FCA1, 6 in &FCA9 and 0 in &FCB1.
+
+ Port A of the 6522 VIA is available for use as an extra 'user port', and
+ Port B is used internally.
+
+ Note : Line (Horizontal) sync pulses are available on PB6
+ Field (Vertical) sync pulses are available on CB1
+
+**********************************************************************/
+
+
+#include "emu.h"
+#include "cc500.h"
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+DEFINE_DEVICE_TYPE(BBC_CC500, bbc_cc500_device, "bbc_cc500", "CTS Colour Card 500")
+
+
+//-------------------------------------------------
+// ROM( cc500 )
+//-------------------------------------------------
+
+ROM_START(cc500)
+ ROM_REGION(0x4000, "exp_rom", 0)
+ ROM_LOAD("cts_palette_1.10.rom", 0x0000, 0x2000, CRC(93533144) SHA1(e645afdc5c7574a487ff484b79ea21a3b476f847))
+ROM_END
+
+//-------------------------------------------------
+// device_add_mconfig - add device configuration
+//-------------------------------------------------
+
+void bbc_cc500_device::device_add_mconfig(machine_config &config)
+{
+ VIA6522(config, m_via, DERIVED_CLOCK(1, 1));
+ m_via->readpa_handler().set(m_userport, FUNC(bbc_userport_slot_device::pb_r));
+ m_via->writepa_handler().set(m_userport, FUNC(bbc_userport_slot_device::pb_w));
+ m_via->irq_handler().set(DEVICE_SELF_OWNER, FUNC(bbc_1mhzbus_slot_device::irq_w));
+
+ BBC_USERPORT_SLOT(config, m_userport, bbc_userport_devices, nullptr);
+ m_userport->cb1_handler().set(m_via, FUNC(via6522_device::write_ca1));
+ m_userport->cb2_handler().set(m_via, FUNC(via6522_device::write_ca2));
+
+ BBC_1MHZBUS_SLOT(config, m_1mhzbus, DERIVED_CLOCK(1, 1), bbc_1mhzbus_devices, nullptr);
+ m_1mhzbus->irq_handler().set(DEVICE_SELF_OWNER, FUNC(bbc_1mhzbus_slot_device::irq_w));
+ m_1mhzbus->nmi_handler().set(DEVICE_SELF_OWNER, FUNC(bbc_1mhzbus_slot_device::nmi_w));
+}
+
+//-------------------------------------------------
+// rom_region - device-specific ROM region
+//-------------------------------------------------
+
+const tiny_rom_entry* bbc_cc500_device::device_rom_region() const
+{
+ return ROM_NAME(cc500);
+}
+
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// bbc_cc500_device - constructor
+//-------------------------------------------------
+
+bbc_cc500_device::bbc_cc500_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+ : device_t(mconfig, BBC_CC500, tag, owner, clock)
+ , device_bbc_1mhzbus_interface(mconfig, *this)
+ , m_palette(*this, ":palette")
+ , m_1mhzbus(*this, "1mhzbus")
+ , m_via(*this, "via")
+ , m_userport(*this, "userport")
+{
+}
+
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void bbc_cc500_device::device_start()
+{
+ memset(m_palette_ram, 0, sizeof(m_palette_ram));
+
+ /* register for save states */
+ save_item(NAME(m_palette_ram));
+}
+
+
+//**************************************************************************
+// IMPLEMENTATION
+//**************************************************************************
+
+uint8_t bbc_cc500_device::fred_r(offs_t offset)
+{
+ uint8_t data = 0xff;
+
+ switch (offset & 0xf0)
+ {
+ case 0x90:
+ data = m_via->read(offset & 0x0f);
+ break;
+ }
+
+ data &= m_1mhzbus->fred_r(offset);
+
+ return data;
+}
+
+void bbc_cc500_device::fred_w(offs_t offset, uint8_t data)
+{
+ switch (offset & 0xf0)
+ {
+ case 0x90:
+ m_via->write(offset & 0x0f, data);
+ break;
+
+ case 0xa0: case 0xb0:
+ switch (offset & 0x18)
+ {
+ case 0x00:
+ m_palette_ram[~offset & 0x07].set_r((data << 4) | (data & 0x0f));
+ break;
+ case 0x08:
+ m_palette_ram[~offset & 0x07].set_g((data << 4) | (data & 0x0f));
+ break;
+ case 0x10:
+ m_palette_ram[~offset & 0x07].set_b((data << 4) | (data & 0x0f));
+ break;
+ }
+ m_palette->set_pen_colors(0, &m_palette_ram[0], 8);
+ break;
+ }
+
+ m_1mhzbus->fred_w(offset, data);
+}
+
+uint8_t bbc_cc500_device::jim_r(offs_t offset)
+{
+ return m_1mhzbus->jim_r(offset);
+}
+
+void bbc_cc500_device::jim_w(offs_t offset, uint8_t data)
+{
+ m_1mhzbus->jim_w(offset, data);
+}