heathzenith/h89.cpp: Add wait states for mms 77316 fdc (#12502)

Author: mgarlanger

src/mame/heathzenith/h89.cpp

@@ -150,6 +150,8 @@ class h89_base_state : public driver_device
 
 	void h89_base_io(address_map &map);
 
+	void set_wait_state(int data);
+
 	u8 raise_NMI_r();
 	void raise_NMI_w(u8 data);
 	void console_intr(int data);
@@ -247,14 +249,14 @@ class h89_mms_state : public h89_base_state
 public:
 	h89_mms_state(const machine_config &mconfig, device_type type, const char *tag):
 		h89_base_state(mconfig, type, tag),
-		m_mms(*this, "mms_fdc")
+		m_mms316(*this, "mms77316")
 	{
 	}
 
 	void h89_mms(machine_config &config);
 
 protected:
-	required_device<mms77316_fdc_device> m_mms;
+	required_device<mms77316_fdc_device> m_mms316;
 
 	void h89_mms_io(address_map &map);
 };
@@ -466,7 +468,7 @@ void h89_mms_state::h89_mms_io(address_map &map)
 	h89_base_state::h89_base_io(map);
 
 	// Add MMS 77316 Double Density Controller
-	map(0x38,0x3f).rw(m_mms, FUNC(mms77316_fdc_device::read), FUNC(mms77316_fdc_device::write));
+	map(0x38,0x3f).rw(m_mms316, FUNC(mms77316_fdc_device::read), FUNC(mms77316_fdc_device::write));
 }
 
 
@@ -783,6 +785,16 @@ void h89_base_state::machine_reset()
 	update_mem_view();
 }
 
+void h89_base_state::set_wait_state(int data)
+{
+	m_maincpu->set_input_line(Z80_INPUT_LINE_WAIT, data);
+	if (data)
+	{
+		machine().scheduler().synchronize();
+		m_maincpu->defer_access();
+	}
+}
+
 u8 h89_base_state::raise_NMI_r()
 {
 	m_maincpu->pulse_input_line(INPUT_LINE_NMI, attotime::from_usec(2));
@@ -1010,9 +1022,10 @@ void h89_mms_state::h89_mms(machine_config &config)
 	m_intr_socket->set_default_option("mms");
 	m_intr_socket->set_fixed(true);
 
-	MMS77316_FDC(config, m_mms);
-	m_mms->drq_cb().set(m_intr_socket, FUNC(heath_intr_socket::set_drq));
-	m_mms->irq_cb().set(m_intr_socket, FUNC(heath_intr_socket::set_irq));
+	MMS77316_FDC(config, m_mms316);
+	m_mms316->drq_cb().set(m_intr_socket, FUNC(heath_intr_socket::set_drq));
+	m_mms316->irq_cb().set(m_intr_socket, FUNC(heath_intr_socket::set_irq));
+	m_mms316->wait_cb().set(FUNC(h89_mms_state::set_wait_state));
 }
 
 

src/mame/heathzenith/mms77316_fdc.cpp

@@ -41,6 +41,7 @@ mms77316_fdc_device::mms77316_fdc_device(const machine_config &mconfig, const ch
 	device_t(mconfig, MMS77316_FDC, tag, owner, 0),
 	m_irq_cb(*this),
 	m_drq_cb(*this),
+	m_wait_cb(*this),
 	m_fdc(*this, "mms_fdc"),
 	m_floppies(*this, "mms_fdc:%u", 0U)
 {
@@ -84,7 +85,7 @@ void mms77316_fdc_device::ctrl_w(u8 val)
 			floppy_image_device *floppy = elem->get_device();
 			if (floppy)
 			{
-				// turn on all installed 5" floppies
+				// set motor for installed 5" drives
 				floppy->mon_w(!five_in_drv);
 			}
 		}
@@ -93,10 +94,12 @@ void mms77316_fdc_device::ctrl_w(u8 val)
 
 void mms77316_fdc_device::data_w(u8 val)
 {
-	if (burstMode())
+	if (burst_mode_r() && !m_drq && !m_irq)
 	{
-		// TODO add wait states in burst mode, currently blocked on Z80 properly supporting wait states
-		LOGBURST("%s: burst_mode: %d\n", FUNCNAME, val);
+		LOGBURST("%s: burst_mode_r\n", FUNCNAME);
+		m_wait_cb(ASSERT_LINE);
+
+		return;
 	}
 
 	m_fdc->data_w(val);
@@ -133,10 +136,12 @@ void mms77316_fdc_device::write(offs_t reg, u8 val)
 
 u8 mms77316_fdc_device::data_r()
 {
-	if (burstMode())
+	if (burst_mode_r() && !m_drq && !m_irq)
 	{
-		// TODO add wait states in burst mode, currently blocked on Z80 properly supporting wait states
-		LOGBURST("%s: burst_mode\n", FUNCNAME);
+		LOGBURST("%s: burst_mode setting wait state\n", FUNCNAME);
+		m_wait_cb(ASSERT_LINE);
+
+		return(0x00);
 	}
 
 	return m_fdc->data_r();
@@ -193,6 +198,7 @@ void mms77316_fdc_device::device_reset()
 
 	m_irq_cb(0);
 	m_drq_cb(0);
+	m_wait_cb(0);
 	for (int i = 0; i < 4; i++)
 	{
 		auto elem = m_floppies[i];
@@ -265,6 +271,7 @@ void mms77316_fdc_device::set_irq(int state)
 
 	if (state)
 	{
+		m_wait_cb(CLEAR_LINE);
 		m_drq_count = 0;
 	}
 
@@ -275,16 +282,22 @@ void mms77316_fdc_device::set_irq(int state)
 
 void mms77316_fdc_device::set_drq(int state)
 {
-	bool drq_allowed = false;
-
 	LOGLINES("set drq, allowed: %d state: %d\n", m_drq_allowed, state);
+
 	m_drq = state;
 
-	if (m_drq)
+	if (burst_mode_r())
 	{
-		// even if drq bit is not set, trigger if the first one after an IRQ.
-		drq_allowed = m_drq_allowed || (m_drq_count++ == 0);
-	}
+		LOGBURST("%s: in burst mode drq: %d, m_drq_count: %d\n", FUNCNAME, m_drq, m_drq_count);
+		if (m_drq)
+		{
+			m_wait_cb(CLEAR_LINE);
+		}
 
-	m_drq_cb(drq_allowed ? m_drq : CLEAR_LINE);
+		m_drq_cb(m_drq_count == 0 ? m_drq : CLEAR_LINE);
+	}
+	else
+	{
+		m_drq_cb(m_drq_allowed ? m_drq : CLEAR_LINE);
+	}
 }

src/mame/heathzenith/mms77316_fdc.h

@@ -26,6 +26,7 @@ class mms77316_fdc_device : public device_t
 
 	auto irq_cb() { return m_irq_cb.bind(); }
 	auto drq_cb() { return m_drq_cb.bind(); }
+	auto wait_cb() { return m_wait_cb.bind(); }
 
 protected:
 
@@ -43,12 +44,13 @@ class mms77316_fdc_device : public device_t
 	// Burst mode was required for a 2 MHz Z80 to handle 8" DD data rates.
 	// The typical irq/drq was too slow, this utilizes wait states to read the
 	// WD1797 data port once the drq line is high.
-	inline bool burstMode() { return !m_drq_allowed; }
+	inline bool burst_mode_r() { return !m_drq_allowed; }
 
 private:
 
 	devcb_write_line                           m_irq_cb;
 	devcb_write_line                           m_drq_cb;
+	devcb_write_line                           m_wait_cb;
 
 	required_device<fd1797_device>             m_fdc;
 	required_device_array<floppy_connector, 8> m_floppies;