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-rw-r--r--src/devices/bus/tanbus/ravdu.cpp195
1 files changed, 195 insertions, 0 deletions
diff --git a/src/devices/bus/tanbus/ravdu.cpp b/src/devices/bus/tanbus/ravdu.cpp
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+++ b/src/devices/bus/tanbus/ravdu.cpp
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+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/**********************************************************************
+
+ Ralph Allen Colour VDU Card
+
+ http://www.microtan.ukpc.net/6809/Video.pdf
+
+ TODO:
+ - use MC6845 screen_update to implement cursor, requires interlace
+ - verify whether INHRAM and BE lines are used
+
+**********************************************************************/
+
+
+#include "emu.h"
+#include "ravdu.h"
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+DEFINE_DEVICE_TYPE(TANBUS_RAVDU, tanbus_ravdu_device, "tanbus_ravdu", "Ralph Allen Colour VDU Card")
+
+
+//-------------------------------------------------
+// device_add_mconfig - add device configuration
+//-------------------------------------------------
+
+void tanbus_ravdu_device::device_add_mconfig(machine_config &config)
+{
+ SCREEN(config, m_screen, SCREEN_TYPE_RASTER);
+ m_screen->set_refresh_hz(50);
+ m_screen->set_vblank_time(ATTOSECONDS_IN_USEC(2500));
+ m_screen->set_size(1536, 624);
+ m_screen->set_visarea(0, 972 - 1, 0, 500 - 1);
+ //m_screen->set_screen_update("mc6845", FUNC(mc6845_device::screen_update)); // TODO: implement interlace in mc6845
+ m_screen->set_screen_update("saa5055", FUNC(saa5055_device::screen_update));
+
+ MC6845(config, m_crtc, DERIVED_CLOCK(1, 4));
+ m_crtc->set_screen(nullptr);
+ m_crtc->set_show_border_area(false);
+ m_crtc->set_char_width(12);
+ m_crtc->out_vsync_callback().set(FUNC(tanbus_ravdu_device::vsync_changed));
+ m_crtc->set_update_row_callback(FUNC(tanbus_ravdu_device::crtc_update_row), this);
+
+ SAA5055(config, m_trom, DERIVED_CLOCK(1, 1));
+ m_trom->d_cb().set(FUNC(tanbus_ravdu_device::videoram_r));
+ m_trom->set_screen_size(81, 25, 81);
+}
+
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// tanbus_ravdu_device - constructor
+//-------------------------------------------------
+
+tanbus_ravdu_device::tanbus_ravdu_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+ : device_t(mconfig, TANBUS_RAVDU, tag, owner, clock)
+ , device_tanbus_interface(mconfig, *this)
+ , m_screen(*this, "screen")
+ , m_crtc(*this, "mc6845")
+ , m_trom(*this, "saa5055")
+{
+}
+
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void tanbus_ravdu_device::device_start()
+{
+ set_clock(m_tanbus->clock());
+ m_videoram = std::make_unique<uint8_t[]>(0x800);
+ memset(m_videoram.get(), 0xff, sizeof(uint8_t) * 0x800);
+
+ save_pointer(NAME(m_videoram), 0x800);
+}
+
+//-------------------------------------------------
+// device_reset - device-specific reset
+//-------------------------------------------------
+
+void tanbus_ravdu_device::device_reset()
+{
+}
+
+//-------------------------------------------------
+// read - card read
+//-------------------------------------------------
+
+uint8_t tanbus_ravdu_device::read(offs_t offset, int inhrom, int inhram, int be)
+{
+ uint8_t data = 0xff;
+
+ if ((offset & 0xf800) == 0xe000)
+ {
+ data = m_videoram[offset & 0x7ff];
+ }
+
+ switch (offset)
+ {
+ case 0xe7fe:
+ data = m_crtc->status_r();
+ break;
+ case 0xe7ff:
+ data = m_crtc->register_r();
+ break;
+ }
+
+ return data;
+}
+
+//-------------------------------------------------
+// write - card write
+//-------------------------------------------------
+
+void tanbus_ravdu_device::write(offs_t offset, uint8_t data, int inhrom, int inhram, int be)
+{
+ if ((offset & 0xf800) == 0xe000)
+ {
+ m_videoram[offset & 0x7ff] = data;
+ }
+
+ switch (offset)
+ {
+ case 0xe7fe:
+ m_crtc->address_w(data);
+ break;
+ case 0xe7ff:
+ m_crtc->register_w(data);
+ break;
+ }
+}
+
+//-------------------------------------------------
+// set_inhibit_lines
+//-------------------------------------------------
+
+void tanbus_ravdu_device::set_inhibit_lines(offs_t offset, int &inhram, int &inhrom)
+{
+ if ((offset & 0xf800) == 0xe000)
+ {
+ inhram = 1;
+ }
+};
+
+//**************************************************************************
+// IMPLEMENTATION
+//**************************************************************************
+
+READ8_MEMBER(tanbus_ravdu_device::videoram_r)
+{
+ return m_videoram[offset & 0x7ff];
+}
+
+MC6845_UPDATE_ROW(tanbus_ravdu_device::crtc_update_row)
+{
+ uint32_t *p = &bitmap.pix32(y);
+
+ m_trom->lose_w(1);
+ m_trom->lose_w(0);
+
+ for (int column = 0; column < x_count; column++)
+ {
+ m_trom->write(m_videoram[(ma + column) & 0x7ff]);
+
+ m_trom->f1_w(1);
+ m_trom->f1_w(0);
+
+ for (int bit = 0; bit < 12; bit++)
+ {
+ m_trom->tr6_w(1);
+ m_trom->tr6_w(0);
+
+ int col = m_trom->get_rgb() ^ ((column == cursor_x) ? 7 : 0);
+
+ int r = BIT(col, 0) * 0xff;
+ int g = BIT(col, 1) * 0xff;
+ int b = BIT(col, 2) * 0xff;
+
+ *p++ = rgb_t(r, g, b);
+ }
+ }
+}
+
+WRITE_LINE_MEMBER(tanbus_ravdu_device::vsync_changed)
+{
+ m_trom->dew_w(state);
+}