bbc: fdc intrq/drq causes nmi

src/mame/drivers/bbc.c

@@ -864,7 +864,7 @@ static MACHINE_CONFIG_DERIVED( bbcb, bbca )
 
 	/* fdc */
 	MCFG_DEVICE_ADD("i8271" , I8271 , 0)
-	MCFG_I8271_IRQ_CALLBACK(WRITELINE(bbc_state, bbc_i8271_interrupt))
+	MCFG_I8271_IRQ_CALLBACK(INPUTLINE("maincpu", INPUT_LINE_NMI))
 	MCFG_I8271_HDL_CALLBACK(WRITELINE(bbc_state, motor_w))
 	MCFG_I8271_OPT_CALLBACK(WRITELINE(bbc_state, side_w))
 	MCFG_FLOPPY_DRIVE_ADD("i8271:0", bbc_floppies_525, "qd", bbc_state::floppy_formats_bbc)
@@ -889,8 +889,8 @@ static MACHINE_CONFIG_DERIVED(bbcb1770, bbcb)
 	MCFG_DEVICE_REMOVE("i8271")
 
 	MCFG_WD1770_ADD("wd1770", XTAL_16MHz / 2)
-	MCFG_WD_FDC_INTRQ_CALLBACK(WRITELINE(bbc_state, bbc_wd177x_intrq_w))
+	MCFG_WD_FDC_INTRQ_CALLBACK(WRITELINE(bbc_state, fdc_intrq_w))
-	MCFG_WD_FDC_DRQ_CALLBACK(WRITELINE(bbc_state, bbc_wd177x_drq_w))
+	MCFG_WD_FDC_DRQ_CALLBACK(WRITELINE(bbc_state, fdc_drq_w))
 
 	MCFG_FLOPPY_DRIVE_ADD("wd1770:0", bbc_floppies_525, "qd", bbc_state::floppy_formats_bbcm)
 	MCFG_FLOPPY_DRIVE_SOUND(true)
@@ -1166,8 +1166,8 @@ static MACHINE_CONFIG_START( bbcm, bbc_state )
 
 	/* fdc */
 	MCFG_WD1770_ADD("wd1770", XTAL_16MHz / 2)
-	MCFG_WD_FDC_INTRQ_CALLBACK(WRITELINE(bbc_state, bbc_wd177x_intrq_w))
+	MCFG_WD_FDC_INTRQ_CALLBACK(WRITELINE(bbc_state, fdc_intrq_w))
-	MCFG_WD_FDC_DRQ_CALLBACK(WRITELINE(bbc_state, bbc_wd177x_drq_w))
+	MCFG_WD_FDC_DRQ_CALLBACK(WRITELINE(bbc_state, fdc_drq_w))
 
 	MCFG_FLOPPY_DRIVE_ADD("wd1770:0", bbc_floppies_525, "qd", bbc_state::floppy_formats_bbcm)
 	MCFG_FLOPPY_DRIVE_SOUND(true)
@@ -1271,8 +1271,8 @@ static MACHINE_CONFIG_DERIVED( bbcmc, bbcm )
 	MCFG_DEVICE_REMOVE("wd1770")
 
 	MCFG_WD1772_ADD("wd1772", XTAL_16MHz / 2)
-	MCFG_WD_FDC_INTRQ_CALLBACK(WRITELINE(bbc_state, bbc_wd177x_intrq_w))
+	MCFG_WD_FDC_INTRQ_CALLBACK(WRITELINE(bbc_state, fdc_intrq_w))
-	MCFG_WD_FDC_DRQ_CALLBACK(WRITELINE(bbc_state, bbc_wd177x_drq_w))
+	MCFG_WD_FDC_DRQ_CALLBACK(WRITELINE(bbc_state, fdc_drq_w))
 
 	MCFG_FLOPPY_DRIVE_ADD("wd1772:0", bbc_floppies_35, "qd", bbc_state::floppy_formats_bbcmc)
 	MCFG_FLOPPY_DRIVE_SOUND(true)

src/mame/includes/bbc.h

@@ -154,8 +154,6 @@ public:
 	DECLARE_READ8_MEMBER(bbcb_via_user_read_portb);
 	DECLARE_WRITE8_MEMBER(bbcb_via_user_write_portb);
 	DECLARE_WRITE_LINE_MEMBER(bbcb_via_user_irq_w);
-	DECLARE_WRITE_LINE_MEMBER(bbc_wd177x_intrq_w);
-	DECLARE_WRITE_LINE_MEMBER(bbc_wd177x_drq_w);
 	DECLARE_WRITE_LINE_MEMBER(bbc_vsync);
 	void update_acia_rxd();
 	void update_acia_dcd();
@@ -166,7 +164,8 @@ public:
 	DECLARE_WRITE_LINE_MEMBER(write_dcd_serial);
 	DECLARE_WRITE_LINE_MEMBER(write_cts_serial);
 	DECLARE_INPUT_CHANGED_MEMBER( trigger_reset );
-	DECLARE_WRITE_LINE_MEMBER(bbc_i8271_interrupt);
+	DECLARE_WRITE_LINE_MEMBER(fdc_intrq_w);
+	DECLARE_WRITE_LINE_MEMBER(fdc_drq_w);
 	DECLARE_WRITE_LINE_MEMBER(motor_w);
 	DECLARE_WRITE_LINE_MEMBER(side_w);
 
@@ -344,21 +343,13 @@ public: // HACK FOR MC6845
 	emu_timer *m_tape_timer;
 
 
-							/**************************************
-							   i8271 disc control
-							***************************************/
-
-	int m_previous_i8271_int_state; // 8271 interrupt status
-
 							/**************************************
 							   WD1770 disc control
 							***************************************/
 
 	int m_drive_control;
-	int m_wd177x_irq_state;
+	int m_fdc_irq;
-	int m_wd177x_drq_state;
+	int m_fdc_drq;
-	int m_previous_wd177x_int_state;
-	int m_wd177x_int_enabled;
 
 							/**************************************
 							   Video Code
@@ -409,7 +400,7 @@ public: // HACK FOR MC6845
 	int m_videoULA_palette1[16];
 	int *m_videoULA_palette_lookup;
 
-	void bbcbp_setvideoshadow(int vdusel);
+	void bbc_setvideoshadow(int vdusel);
 	void common_init(int memorySize);
 	void set_pixel_lookup();
 	void set_cursor(bbc_state *state);
@@ -422,10 +413,9 @@ public: // HACK FOR MC6845
 	int bbc_keyboard(address_space &space, int data);
 	void bbcb_IC32_initialise(bbc_state *state);
 	void MC146818_set(address_space &space);
-	void bbc_TMSint(int status);
 	void MC6850_Receive_Clock(int new_clock);
 	void BBC_Cassette_motor(unsigned char status);
-	void bbc_update_fdq_int(int state);
+	void bbc_update_nmi();
 	unsigned int calculate_video_address(int ma,int ra);
 	required_device<palette_device> m_palette;
 };

src/mame/machine/bbc.c

@@ -136,7 +136,7 @@ WRITE8_MEMBER(bbc_state::bbc_page_selectbp_w)
 	{
 		//the video display should now use this flag to display the shadow ram memory
 		m_vdusel=BIT(data,7);
-		bbcbp_setvideoshadow(m_vdusel);
+		bbc_setvideoshadow(m_vdusel);
 		//need to make the video display do a full screen refresh for the new memory area
 		m_bank2->set_base(m_region_maincpu->base() + 0x3000);
 	}
@@ -349,7 +349,7 @@ WRITE8_MEMBER(bbc_state::bbcm_ACCCON_write)
 		m_bank7->set_base(m_region_os->base());
 	}
 
-	bbcbp_setvideoshadow(m_ACCCON_D);
+	bbc_setvideoshadow(m_ACCCON_D);
 
 
 	if (m_ACCCON_X)
@@ -1424,27 +1424,6 @@ WRITE_LINE_MEMBER(bbc_state::write_acia_clock)
 ***************************************/
 
 
-WRITE_LINE_MEMBER(bbc_state::bbc_i8271_interrupt)
-{
-	/* I'm assuming that the nmi is edge triggered */
-	/* a interrupt from the fdc will cause a change in line state, and
-	the nmi will be triggered, but when the state changes because the int
-	is cleared this will not cause another nmi */
-	/* I'll emulate it like this to be sure */
-
-	if (state != m_previous_i8271_int_state)
-	{
-		if (state)
-		{
-			/* I'll pulse it because if I used hold-line I'm not sure
-			it would clear - to be checked */
-			m_maincpu->set_input_line(INPUT_LINE_NMI, PULSE_LINE);
-		}
-	}
-
-	m_previous_i8271_int_state = state;
-}
-
 WRITE_LINE_MEMBER(bbc_state::motor_w)
 {
 	m_i8271->subdevice<floppy_connector>("0")->get_device()->mon_w(!state);
@@ -1463,6 +1442,38 @@ WRITE_LINE_MEMBER(bbc_state::side_w)
 ***************************************/
 
 
+/* wd177x_IRQ_SET and latch bit 4 (nmi_enable) are NAND'ED together
+   wd177x_DRQ_SET and latch bit 4 (nmi_enable) are NAND'ED together
+   the output of the above two NAND gates are then OR'ED together and sent to the 6502 NMI line.
+    DRQ and IRQ are active low outputs from wd177x. We use wd177x_DRQ_SET for DRQ = 0,
+    and wd177x_DRQ_CLR for DRQ = 1. Similarly wd177x_IRQ_SET for IRQ = 0 and wd177x_IRQ_CLR
+    for IRQ = 1.
+
+  The above means that if IRQ or DRQ are set, a interrupt should be generated.
+  The nmi_enable decides if interrupts are actually triggered.
+  The nmi is edge triggered, and triggers on a +ve edge.
+*/
+
+
+void bbc_state::bbc_update_nmi()
+{
+	if (m_fdc_irq || m_fdc_drq)
+		m_maincpu->set_input_line(INPUT_LINE_NMI, PULSE_LINE);
+}
+
+WRITE_LINE_MEMBER(bbc_state::fdc_intrq_w)
+{
+	m_fdc_irq = state;
+	bbc_update_nmi();
+
+}
+
+WRITE_LINE_MEMBER(bbc_state::fdc_drq_w)
+{
+	m_fdc_drq = state;
+	bbc_update_nmi();
+}
+
 /*
    B/ B+ drive control:
 
@@ -1477,67 +1488,6 @@ WRITE_LINE_MEMBER(bbc_state::side_w)
          0        Drive select 0.
 */
 
-/*
-density select
-single density is as the 8271 disc format
-double density is as the 8271 disc format but with 16 sectors per track
-*/
-
-
-/* wd177x_IRQ_SET and latch bit 4 (nmi_enable) are NAND'ED together
-   wd177x_DRQ_SET and latch bit 4 (nmi_enable) are NAND'ED together
-   the output of the above two NAND gates are then OR'ED together and sent to the 6502 NMI line.
-    DRQ and IRQ are active low outputs from wd177x. We use wd177x_DRQ_SET for DRQ = 0,
-    and wd177x_DRQ_CLR for DRQ = 1. Similarly wd177x_IRQ_SET for IRQ = 0 and wd177x_IRQ_CLR
-    for IRQ = 1.
-
-  The above means that if IRQ or DRQ are set, a interrupt should be generated.
-  The nmi_enable decides if interrupts are actually triggered.
-  The nmi is edge triggered, and triggers on a +ve edge.
-*/
-
-void bbc_state::bbc_update_fdq_int(int state)
-{
-	int bbc_state;
-
-	/* if drq or irq is set, and interrupt is enabled */
-	if ((m_wd177x_irq_state || m_wd177x_drq_state) && (m_wd177x_int_enabled))
-	{
-		/* int trigger */
-		bbc_state = 1;
-	}
-	else
-	{
-		/* do not trigger int */
-		bbc_state = 0;
-	}
-	/* nmi is edge triggered, and triggers when the state goes from clear->set.
-	Here we are checking this transition before triggering the nmi */
-	if (bbc_state != m_previous_wd177x_int_state)
-	{
-		if (bbc_state)
-		{
-			/* I'll pulse it because if I used hold-line I'm not sure
-			it would clear - to be checked */
-			m_maincpu->set_input_line(INPUT_LINE_NMI,PULSE_LINE);
-		}
-	}
-
-	m_previous_wd177x_int_state = bbc_state;
-}
-
-WRITE_LINE_MEMBER(bbc_state::bbc_wd177x_intrq_w)
-{
-	m_wd177x_irq_state = state;
-	bbc_update_fdq_int(state);
-}
-
-WRITE_LINE_MEMBER(bbc_state::bbc_wd177x_drq_w)
-{
-	m_wd177x_drq_state = state;
-	bbc_update_fdq_int(state);
-}
-
 WRITE8_MEMBER(bbc_state::bbc_wd1770_status_w)
 {
 	floppy_image_device *floppy = NULL;
@@ -1558,14 +1508,21 @@ WRITE8_MEMBER(bbc_state::bbc_wd1770_status_w)
 
 	// bit 5: reset
 	if (!BIT(data, 5)) m_wd1770->soft_reset();
-
-	// bit 4: interrupt enable
-	m_wd177x_int_enabled = !BIT(data, 4);
 }
 
-/***************************************
+/*
-BBC MASTER DISC SUPPORT
+   Master drive control:
-***************************************/
+
+        Bit       Meaning
+        -----------------
+        7,6       Not used.
+         5        Double density select (0 = double, 1 = single).
+         4        Side select (0 = side 0, 1 = side 1).
+         3        Drive select 2.
+         2        Reset drive controller chip. (0 = reset controller, 1 = no reset)
+         1        Drive select 1.
+         0        Drive select 0.
+*/
 
 READ8_MEMBER(bbc_state::bbcm_wd177xl_read)
 {
@@ -1593,8 +1550,6 @@ WRITE8_MEMBER(bbc_state::bbcm_wd1770l_write)
 
 	// bit 2: reset
 	if (!BIT(data, 2)) m_wd1770->soft_reset();
-
-	m_wd177x_int_enabled = 1;
 }
 
 WRITE8_MEMBER(bbc_state::bbcm_wd1772l_write)
@@ -1618,8 +1573,6 @@ WRITE8_MEMBER(bbc_state::bbcm_wd1772l_write)
 
 	// bit 2: reset
 	if (!BIT(data, 2)) m_wd1772->soft_reset();
-
-	m_wd177x_int_enabled = 1;
 }
 
 /**************************************
@@ -1797,8 +1750,6 @@ MACHINE_RESET_MEMBER(bbc_state, bbca)
 MACHINE_START_MEMBER(bbc_state, bbcb)
 {
 	m_mc6850_clock = 0;
-	m_previous_i8271_int_state=0;
-	m_previous_wd177x_int_state=1;
 	bbc_setup_banks(m_bank4, 16, 0, 0x4000);
 }
 
@@ -1833,14 +1784,12 @@ MACHINE_RESET_MEMBER(bbc_state, bbcbp)
 {
 	m_Speech = 1;
 	m_bank1->set_base(m_region_maincpu->base());
-	m_bank2->set_base(m_region_maincpu->base() + 0x03000);  /* bank 2 screen/shadow ram     from 3000 to 7fff */
+	m_bank2->set_base(m_region_maincpu->base() + 0x3000);  /* bank 2 screen/shadow ram     from 3000 to 7fff */
 	m_bank4->set_entry(0);
 	m_bank6->set_entry(0);
-	m_bank7->set_base(m_region_os->base());                 /* bank 7 points at the OS rom  from c000 to ffff */
+	m_bank7->set_base(m_region_os->base());                /* bank 7 points at the OS rom  from c000 to ffff */
 
 	bbcb_IC32_initialise(this);
-
-	m_previous_wd177x_int_state=1;
 }
 
 
@@ -1868,6 +1817,4 @@ MACHINE_RESET_MEMBER(bbc_state, bbcm)
 	m_bank7->set_base(m_region_os->base());                /* bank 6 OS rom of RAM         from c000 to dfff */
 
 	bbcb_IC32_initialise(this);
-
-	m_previous_wd177x_int_state=1;
 }

src/mame/video/bbc.c

@@ -272,10 +272,13 @@ WRITE_LINE_MEMBER(bbc_state::bbc_vsync)
 }
 
 
-/**** BBC B+ Shadow Ram change ****/
+/**** BBC B+/Master Shadow Ram change ****/
 
-void bbc_state::bbcbp_setvideoshadow(int vdusel)
+void bbc_state::bbc_setvideoshadow(int vdusel)
 {
+	// LYNNE lives at 0xb000 in our map, but the offset we use here is 0x8000
+	// as the video circuitry will already be looking at 0x3000 or so above
+	// the offset.
 	if (vdusel)
 		m_BBC_Video_RAM = m_region_maincpu->base()+0x8000;
 	else