scn2674: Add BREQ output; get a bit smarter about screen reconfiguration (nw)

src/devices/video/scn2674.cpp

@@ -14,7 +14,7 @@
 #define LOG_COMMAND (1 << 1)
 #define LOG_INTR    (1 << 2)
 #define LOG_READ    (1 << 3)
-#define VERBOSE     (0)
+#define VERBOSE     (1)
 #include "logmacro.h"
 
 
@@ -43,6 +43,7 @@ scn2674_device::scn2674_device(const machine_config &mconfig, device_type type,
 	, device_video_interface(mconfig, *this)
 	, device_memory_interface(mconfig, *this)
 	, m_intr_cb(*this)
+	, m_breq_cb(*this)
 	, m_IR_pointer(0)
 	, m_screen1_address(0), m_screen2_address(0)
 	, m_cursor_address(0)
@@ -103,6 +104,7 @@ void scn2674_device::device_start()
 	// resolve callbacks
 	m_display_cb.bind_relative_to(*owner());
 	m_intr_cb.resolve_safe();
+	m_breq_cb.resolve_safe();
 	m_scanline_timer = timer_alloc(TIMER_SCANLINE);
 	screen().register_screen_bitmap(m_bitmap);
 
@@ -221,9 +223,12 @@ void scn2672_device::write_init_regs(uint8_t data)
 {
 	//LOGMASKED(LOG_COMMAND, "scn2674_write_init_regs %02x %02x\n",m_IR_pointer,data);
 
+	bool parameters_changed = false;
 	switch (m_IR_pointer)
 	{
 	case 0:
+		parameters_changed = m_scanline_per_char_row != ((data & 0x78) >> 3) + 1;
+
 		m_double_ht_wd = BIT(data, 7);
 		m_scanline_per_char_row = ((data & 0x78) >> 3) + 1;
 		m_csync_select = BIT(data, 2);
@@ -252,6 +257,8 @@ void scn2672_device::write_init_regs(uint8_t data)
 		break;
 
 	case 1:
+		parameters_changed = m_equalizing_constant != (data & 0x7f) + 1;
+
 		m_interlace_enable = BIT(data, 7);
 		m_equalizing_constant = (data & 0x7f) + 1;
 
@@ -260,6 +267,8 @@ void scn2672_device::write_init_regs(uint8_t data)
 		break;
 
 	case 2:
+		parameters_changed = m_horz_sync_width != (((data & 0x78) >> 3) * 2) + 2;
+
 		m_horz_sync_width = (((data & 0x78) >> 3) * 2) + 2;
 		m_horz_back_porch = ((data & 0x07) * 4) + 1;
 
@@ -268,6 +277,9 @@ void scn2672_device::write_init_regs(uint8_t data)
 		break;
 
 	case 3:
+		parameters_changed = m_vert_front_porch != (((data & 0xe0) >> 5) * 4) + 4
+			|| m_vert_back_porch != ((data & 0x1f) * 2) + 4;
+
 		m_vert_front_porch = (((data & 0xe0) >> 5) * 4) + 4;
 		m_vert_back_porch = ((data & 0x1f) * 2) + 4;
 
@@ -276,6 +288,8 @@ void scn2672_device::write_init_regs(uint8_t data)
 		break;
 
 	case 4:
+		parameters_changed = m_rows_per_screen != (data & 0x7f) + 1;
+
 		m_rows_per_screen = (data & 0x7f) + 1;
 		m_character_blink_rate_divisor = BIT(data, 7) ? 32 : 16;
 
@@ -284,6 +298,8 @@ void scn2672_device::write_init_regs(uint8_t data)
 		break;
 
 	case 5:
+		parameters_changed = m_character_per_row != data + 1;
+
 		m_character_per_row = data + 1;
 		LOGMASKED(LOG_IR, "IR5 - Active Characters Per Row %02i\n", m_character_per_row);
 		break;
@@ -333,8 +349,7 @@ void scn2672_device::write_init_regs(uint8_t data)
 		break;
 	}
 
-	// Don't reconfigure if the display isn't turned on (incomplete configurations may generate invalid screen parameters)
+	if (parameters_changed)
-	if (m_display_enabled)
 		recompute_parameters();
 
 	m_IR_pointer = std::min(m_IR_pointer + 1, 10);
@@ -345,9 +360,12 @@ void scn2674_device::write_init_regs(uint8_t data)
 {
 	//LOGMASKED(LOG_COMMAND, "scn2674_write_init_regs %02x %02x\n",m_IR_pointer,data);
 
+	bool parameters_changed = false;
 	switch (m_IR_pointer)
 	{
 	case 0:
+		parameters_changed = m_scanline_per_char_row != ((data & 0x78) >> 3) + 1;
+
 		m_double_ht_wd = BIT(data, 7);
 		m_scanline_per_char_row = ((data & 0x78) >> 3) + 1;
 		m_csync_select = BIT(data, 2);
@@ -377,6 +395,8 @@ void scn2674_device::write_init_regs(uint8_t data)
 		break;
 
 	case 1:
+		parameters_changed = m_equalizing_constant != (data & 0x7f) + 1;
+
 		m_interlace_enable = BIT(data, 7);
 		m_equalizing_constant = (data & 0x7f) + 1;
 
@@ -385,6 +405,8 @@ void scn2674_device::write_init_regs(uint8_t data)
 		break;
 
 	case 2:
+		parameters_changed = m_horz_sync_width != (((data & 0x78) >> 3) * 2) + 2;
+
 		m_use_row_table = BIT(data, 7);
 		m_horz_sync_width = (((data & 0x78) >> 3) * 2) + 2;
 		m_horz_back_porch = ((data & 0x07) * 4) - 1;
@@ -395,6 +417,9 @@ void scn2674_device::write_init_regs(uint8_t data)
 		break;
 
 	case 3:
+		parameters_changed = m_vert_front_porch != (((data & 0xe0) >> 5) * 4) + 4
+			|| m_vert_back_porch != ((data & 0x1f) * 2) + 4;
+
 		m_vert_front_porch = (((data & 0xe0) >> 5) * 4) + 4;
 		m_vert_back_porch = ((data & 0x1f) * 2) + 4;
 
@@ -403,6 +428,8 @@ void scn2674_device::write_init_regs(uint8_t data)
 		break;
 
 	case 4:
+		parameters_changed = m_rows_per_screen != (data & 0x7f) + 1;
+
 		m_rows_per_screen = (data & 0x7f) + 1;
 		m_character_blink_rate_divisor = BIT(data, 7) ? 128 : 64;
 
@@ -411,6 +438,8 @@ void scn2674_device::write_init_regs(uint8_t data)
 		break;
 
 	case 5:
+		parameters_changed = m_character_per_row != data + 1;
+
 		m_character_per_row = data + 1;
 		LOGMASKED(LOG_IR, "IR5 - Active Characters Per Row %02i\n", m_character_per_row);
 		break;
@@ -429,6 +458,7 @@ void scn2674_device::write_init_regs(uint8_t data)
 			m_cursor_rate_divisor = BIT(data, 4) ? 64 : 32;
 			m_cursor_blink = BIT(data, 5);
 
+			parameters_changed = m_vsync_width != vsync_table[(data & 0xc0) >> 6];
 			m_vsync_width = vsync_table[(data & 0xc0) >> 6];
 
 			LOGMASKED(LOG_IR, "IR7 - Underline Position %02i\n", m_cursor_underline_position);
@@ -499,8 +529,7 @@ void scn2674_device::write_init_regs(uint8_t data)
 		break;
 	}
 
-	// Don't reconfigure if the display isn't turned on (incomplete configurations may generate invalid screen parameters)
+	if (parameters_changed)
-	if (m_display_enabled)
 		recompute_parameters();
 
 	m_IR_pointer = std::min(m_IR_pointer + 1, 14);
@@ -601,13 +630,7 @@ void scn2674_device::write_interrupt_mask(bool enabled, uint8_t bits)
 	if (BIT(changed_bits, 3))
 		LOGMASKED(LOG_INTR, "Line Zero IRQ %s\n", enabled ? "enabled" : "disabled");
 	if (BIT(changed_bits, 4))
-	{
 		LOGMASKED(LOG_INTR, "V-Blank IRQ %s\n", enabled ? "enabled" : "disabled");
-
-		// hack to allow PC-X to get its first interrupt
-		if (BIT(bits, 4) && !m_display_enabled)
-			recompute_parameters();
-	}
 }
 
 void scn2674_device::write_delayed_command(uint8_t data)
@@ -925,6 +948,12 @@ WRITE8_MEMBER( scn2674_device::write )
 
 void scn2674_device::recompute_parameters()
 {
+	if (!m_equalizing_constant || !m_character_per_row || !m_rows_per_screen)
+	{
+		m_scanline_timer->adjust(attotime::never);
+		return;
+	}
+
 	int horiz_chars_total = (m_equalizing_constant + (m_horz_sync_width << 1)) << 1;
 	int horiz_pix_total = horiz_chars_total * m_hpixels_per_column;
 	int vert_pix_total = m_rows_per_screen * m_scanline_per_char_row + m_vert_front_porch + m_vert_back_porch + m_vsync_width;
@@ -932,12 +961,6 @@ void scn2674_device::recompute_parameters()
 	int max_visible_x = (m_character_per_row * m_hpixels_per_column) - 1;
 	int max_visible_y = (m_rows_per_screen * m_scanline_per_char_row) - 1;
 
-	if (!horiz_pix_total || !vert_pix_total)
-	{
-		m_scanline_timer->adjust(attotime::never);
-		return;
-	}
-
 	//attoseconds_t refresh = clocks_to_attotime(horiz_chars_total * vert_pix_total).as_attoseconds();
 	LOGMASKED(LOG_IR, "width %u height %u max_x %u max_y %u refresh %f\n", horiz_pix_total, vert_pix_total, max_visible_x, max_visible_y, ATTOSECONDS_TO_HZ(refresh));
 
@@ -996,7 +1019,11 @@ void scn2674_device::device_timer(emu_timer &timer, device_timer_id id, int para
 					m_irq_register |= 0x08;
 					m_intr_cb(ASSERT_LINE);
 				}
+				if (m_buffer_mode_select == 3)
+					m_breq_cb(ASSERT_LINE);
 			}
+			else if (m_buffer_mode_select == 3)
+				m_breq_cb(CLEAR_LINE);
 
 			// Handle screen splits
 			for (int s = 0; s < 2; s++)

src/devices/video/scn2674.h

@@ -22,7 +22,9 @@ public:
 
 	// static configuration
 	auto intr_callback() { return m_intr_cb.bind(); }
+	auto breq_callback() { return m_breq_cb.bind(); }
 	void set_character_width(int value) { m_hpixels_per_column = value; }
+
 	template <class FunctionClass>
 	void set_display_callback(void (FunctionClass::*callback)(bitmap_rgb32 &, int, int, uint8_t, uint8_t, uint8_t, uint16_t, bool, bool, bool, bool, bool), const char *name)
 	{
@@ -59,6 +61,7 @@ protected:
 //protected:
 	bitmap_rgb32 m_bitmap;
 	devcb_write_line m_intr_cb;
+	devcb_write_line m_breq_cb;
 
 	uint8_t m_IR_pointer;
 	uint16_t m_screen1_address;

src/mame/drivers/qvt201.cpp

@@ -21,6 +21,7 @@ public:
 	qvt201_state(const machine_config &mconfig, device_type type, const char *tag)
 		: driver_device(mconfig, type, tag)
 		, m_maincpu(*this, "maincpu")
+		, m_mainnmi(*this, "mainnmi")
 		, m_eia(*this, "eia")
 		, m_screen(*this, "screen")
 		, m_p_chargen(*this, "chargen")
@@ -40,6 +41,7 @@ private:
 	void mem_map(address_map &map);
 
 	required_device<cpu_device> m_maincpu;
+	required_device<input_merger_device> m_mainnmi;
 	required_device<rs232_port_device> m_eia;
 	required_device<screen_device> m_screen;
 	required_region_ptr<u8> m_p_chargen;
@@ -73,11 +75,12 @@ WRITE8_MEMBER(qvt201_state::duart_out_w)
 	// OP3 = 132/_80
 	// OP4 = SRV
 	// OP5 = BLOCK/_UL
-	// OP6 = preset NMI flipflop
+	// OP6 = preset MBC NMI flipflop
 	// OP7 = _DATA/TALK (EIA pin 14)
 
 	m_eia->write_rts(BIT(data, 0));
 	m_eia->write_dtr(BIT(data, 1));
+	m_mainnmi->in_w<1>(!BIT(data, 6));
 }
 
 void qvt201_state::mem_map(address_map &map)
@@ -100,8 +103,11 @@ MACHINE_CONFIG_START(qvt201_state::qvt201)
 	MCFG_DEVICE_ADD("maincpu", Z80, 3.6864_MHz_XTAL)
 	MCFG_DEVICE_PROGRAM_MAP(mem_map) // IORQ is not used at all
 
-	MCFG_INPUT_MERGER_ANY_HIGH("mainint") // open collector
+	input_merger_device &mainint(INPUT_MERGER_ANY_HIGH(config, "mainint")); // open collector
-	MCFG_INPUT_MERGER_OUTPUT_HANDLER(INPUTLINE("maincpu", 0))
+	mainint.output_handler().set_inputline("maincpu", INPUT_LINE_IRQ0);
+
+	input_merger_device &mainnmi(INPUT_MERGER_ALL_HIGH(config, "mainnmi"));
+	mainnmi.output_handler().set_inputline("maincpu", INPUT_LINE_NMI);
 
 	MCFG_DEVICE_ADD("duart", SCN2681, 3.6864_MHz_XTAL) // XTAL not directly connected
 	MCFG_MC68681_IRQ_CALLBACK(WRITELINE("mainint", input_merger_device, in_w<1>))
@@ -126,6 +132,7 @@ MACHINE_CONFIG_START(qvt201_state::qvt201)
 	scn2672_device &crtc(SCN2672(config, "crtc", 48.654_MHz_XTAL / 30));
 	crtc.set_character_width(10); // 9 in 132-column mode
 	crtc.intr_callback().set("mainint", FUNC(input_merger_device::in_w<0>));
+	crtc.breq_callback().set("mainnmi", FUNC(input_merger_device::in_w<0>));
 	crtc.set_screen("screen");
 MACHINE_CONFIG_END