x68k: add CZ-7BS1 dma glue logic

src/devices/bus/x68k/x68k_scsiext.cpp

@@ -56,7 +56,7 @@ void x68k_scsiext_device::device_add_mconfig(machine_config &config)
 		{
 			mb89352_device &spc = downcast<mb89352_device &>(*device);
 
-			spc.set_clock(8'000'000); // ?
+			spc.set_clock(10'000'000 / 2); // 10MHz clock from bus
 			spc.out_irq_callback().set(*this, FUNC(x68k_scsiext_device::irq_w));
 			spc.out_dreq_callback().set(*this, FUNC(x68k_scsiext_device::drq_w));
 		});
@@ -68,16 +68,24 @@ x68k_scsiext_device::x68k_scsiext_device(const machine_config &mconfig, const ch
 	, m_slot(nullptr)
 	, m_spc(*this, "scsi:7:spc")
 	, m_rom(*this, "scsiexrom")
+	, m_drq(false)
 {
 }
 
 void x68k_scsiext_device::device_start()
 {
+	save_item(NAME(m_drq));
+
 	m_slot = dynamic_cast<x68k_expansion_slot_device *>(owner());
 
 	m_slot->space().install_rom(0xea0020,0xea1fff, m_rom.target());
 	m_slot->space().unmap_write(0xea0020,0xea1fff);
 	m_slot->space().install_device(0xea0000, 0xea001f, *m_spc, &mb89352_device::map, 0x00ff00ff);
+
+	// replace data register handlers with DMA-aware glue
+	m_slot->space().install_readwrite_handler(0xea0015, 0xea0015,
+		emu::rw_delegate(*this, FUNC(x68k_scsiext_device::data_r)),
+		emu::rw_delegate(*this, FUNC(x68k_scsiext_device::data_w)));
 }
 
 void x68k_scsiext_device::device_reset()
@@ -86,7 +94,8 @@ void x68k_scsiext_device::device_reset()
 
 void x68k_scsiext_device::irq_w(int state)
 {
-	m_slot->irq2_w(state);  // correct?  Or perhaps selectable?
+	// TODO: jumper-configurable IRQ2/IRQ4
+	m_slot->irq2_w(state);
 }
 
 uint8_t x68k_scsiext_device::iack2()
@@ -96,5 +105,36 @@ uint8_t x68k_scsiext_device::iack2()
 
 void x68k_scsiext_device::drq_w(int state)
 {
-	// TODO
+	m_drq = bool(state);
+}
+
+u8 x68k_scsiext_device::data_r()
+{
+	// check for DMA cycle
+	if (m_slot->exown() && !machine().side_effects_disabled())
+	{
+		// negate #DTACK if not requesting a DMA transfer
+		if (!m_drq)
+			m_slot->dtack_w(1);
+
+		return m_spc->dma_r();
+	}
+	else
+		return m_spc->dreg_r();
+
+}
+
+void x68k_scsiext_device::data_w(u8 data)
+{
+	// check for DMA cycle
+	if (m_slot->exown())
+	{
+		// negate #DTACK if not requesting a DMA transfer
+		if (!m_drq)
+			m_slot->dtack_w(1);
+		else
+			m_spc->dma_w(data);
+	}
+	else
+		m_spc->dreg_w(data);
 }

src/devices/bus/x68k/x68k_scsiext.h

@@ -22,23 +22,28 @@ public:
 	x68k_scsiext_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
 
 protected:
-	// device-level overrides
+	// device_t implementation
 	virtual void device_start() override ATTR_COLD;
 	virtual void device_reset() override ATTR_COLD;
 	virtual void device_add_mconfig(machine_config &config) override ATTR_COLD;
 	virtual const tiny_rom_entry *device_rom_region() const override ATTR_COLD;
 
-	// device_x68k_expansion_card_interface overrides
+	// device_x68k_expansion_card_interface implementation
 	virtual uint8_t iack2() override;
 
 private:
 	void irq_w(int state);
 	void drq_w(int state);
 
+	u8 data_r();
+	void data_w(u8 data);
+
 	x68k_expansion_slot_device *m_slot;
 
 	required_device<mb89352_device> m_spc;
 	required_region_ptr<u8> m_rom;
+
+	bool m_drq;
 };
 
 // device type definition

src/devices/bus/x68k/x68kexp.cpp

@@ -53,6 +53,7 @@ x68k_expansion_slot_device::x68k_expansion_slot_device(const machine_config &mco
 	m_out_irq4_cb(*this),
 	m_out_nmi_cb(*this),
 	m_out_reset_cb(*this),
+	m_out_dtack_cb(*this),
 	m_card(nullptr)
 {
 }
@@ -67,6 +68,8 @@ x68k_expansion_slot_device::~x68k_expansion_slot_device()
 
 void x68k_expansion_slot_device::device_start()
 {
+	save_item(NAME(m_exown));
+
 	m_card = get_card_device();
 }
 
@@ -75,3 +78,4 @@ void x68k_expansion_slot_device::irq2_w(int state) { m_out_irq2_cb(state); }
 void x68k_expansion_slot_device::irq4_w(int state) { m_out_irq4_cb(state); }
 void x68k_expansion_slot_device::nmi_w(int state) { m_out_nmi_cb(state); }
 void x68k_expansion_slot_device::reset_w(int state) { m_out_reset_cb(state); }
+void x68k_expansion_slot_device::dtack_w(int state) { m_out_dtack_cb(state); }

src/devices/bus/x68k/x68kexp.h

@@ -115,6 +115,7 @@ public:
 	auto out_irq4_callback() { return m_out_irq4_cb.bind(); }
 	auto out_nmi_callback() { return m_out_nmi_cb.bind(); }
 	auto out_reset_callback() { return m_out_reset_cb.bind(); }
+	auto out_dtack_callback() { return m_out_dtack_cb.bind(); }
 
 	address_space &space() { return *m_space; }
 
@@ -122,22 +123,29 @@ public:
 	void irq4_w(int state);
 	void nmi_w(int state);
 	void reset_w(int state);
+	void dtack_w(int state);
+	bool exown() const { return m_exown; }
 
 	uint8_t iack2() { return (m_card != nullptr) ? m_card->iack2() : 0x18; }
 	uint8_t iack4() { return (m_card != nullptr) ? m_card->iack4() : 0x18; }
+	void exown_w(int state) { m_exown = !state; }
 
 protected:
-	// device-level overrides
+	// device_t implementation
 	virtual void device_start() override ATTR_COLD;
 
 	required_address_space m_space;
 
+private:
 	devcb_write_line    m_out_irq2_cb;
 	devcb_write_line    m_out_irq4_cb;
 	devcb_write_line    m_out_nmi_cb;
 	devcb_write_line    m_out_reset_cb;
+	devcb_write_line    m_out_dtack_cb;
 
 	device_x68k_expansion_card_interface *m_card;
+
+	bool m_exown;
 };
 
 

src/mame/sharp/x68k.cpp

@@ -742,24 +742,24 @@ void x68k_state::irq4_line(int state)
 
 uint8_t x68k_state::iack2()
 {
-	// Relative priority of IACK2-1 and IACK2-2 is unknown
+	// IACK2-1 has higher priority than IACK2-2
 	if (m_exp_irq2[0])
 		return m_expansion[0]->iack2();
 	else if (m_exp_irq2[1])
 		return m_expansion[1]->iack2();
 	else
-		return 0x18; // spurious interrupt
+		return m68000_base_device::autovector(0); // spurious interrupt
 }
 
 uint8_t x68k_state::iack4()
 {
-	// Relative priority of IACK4-1 and IACK4-2 is unknown
+	// IACK4-1 has higher priority than IACK4-2
 	if (m_exp_irq4[0])
 		return m_expansion[0]->iack4();
 	else if (m_exp_irq4[1])
 		return m_expansion[1]->iack4();
 	else
-		return 0x18; // spurious interrupt
+		return m68000_base_device::autovector(0); // spurious interrupt
 }
 
 void x68k_state::cpu_space_map(address_map &map)
@@ -1111,12 +1111,16 @@ void x68k_state::x68000_base(machine_config &config)
 	m_expansion[0]->out_irq2_callback().set(FUNC(x68k_state::irq2_line<0>));
 	m_expansion[0]->out_irq4_callback().set(FUNC(x68k_state::irq4_line<0>));
 	m_expansion[0]->out_nmi_callback().set(nmi, FUNC(input_merger_any_high_device::in_w<0>));
+	m_expansion[0]->out_dtack_callback().set(m_hd63450, FUNC(hd63450_device::dtack_w));
+	m_hd63450->own().append(m_expansion[0], FUNC(x68k_expansion_slot_device::exown_w));
 
 	X68K_EXPANSION_SLOT(config, m_expansion[1], x68000_exp_cards, nullptr);
 	m_expansion[1]->set_space(m_maincpu, AS_PROGRAM);
 	m_expansion[1]->out_irq2_callback().set(FUNC(x68k_state::irq2_line<1>));
 	m_expansion[1]->out_irq4_callback().set(FUNC(x68k_state::irq4_line<1>));
 	m_expansion[1]->out_nmi_callback().set(nmi, FUNC(input_merger_any_high_device::in_w<1>));
+	m_expansion[1]->out_dtack_callback().set(m_hd63450, FUNC(hd63450_device::dtack_w));
+	m_hd63450->own().append(m_expansion[1], FUNC(x68k_expansion_slot_device::exown_w));
 
 	/* internal ram */
 	RAM(config, m_ram).set_default_size("4M").set_extra_options("1M,2M,3M,5M,6M,7M,8M,9M,10M,11M,12M");
@@ -1169,12 +1173,9 @@ void x68ksupr_state::x68ksupr_base(machine_config &config)
 
 			spc.set_clock(40_MHz_XTAL / 8);
 			spc.out_irq_callback().set(*this, FUNC(x68ksupr_state::ioc_irq<IOC_HDD_INT>));
-			spc.out_dreq_callback().set(m_hd63450, FUNC(hd63450_device::drq1_w));
+			// TODO: duplicate DMA glue from CZ-6BS1
 		});
 
-	m_hd63450->dma_read<1>().set("scsi:7:spc", FUNC(mb89352_device::dma_r));
-	m_hd63450->dma_write<1>().set("scsi:7:spc", FUNC(mb89352_device::dma_w));
-
 	VICON(config, m_crtc, 38.86363_MHz_XTAL);
 	m_crtc->set_clock_69m(69.55199_MHz_XTAL);
 	m_crtc->set_screen("screen");