a2gameio: One fine point (nw)

src/devices/bus/a2gameio/gameio.cpp

@@ -11,12 +11,15 @@
     input signals (0-150KΩ resistance) which are converted to
     digital pulses by a NE558 quad timer on the main board. The
     connector also provides several digital switch inputs and
-    "annunciator" outputs, all LS/TTL compatible.
+    "annunciator" outputs, all LS/TTL compatible. Apple joysticks
+    provide active high switches (though at least one third-party
+    product treats them as active low) and Apple main boards have no
+    pullups on these inputs, which thus read 0 if disconnected.
 
     While pins 9 and 16 are unconnected on the Apple II, they provide
     additional digital output and input pins respectively on the Sanyo
     MBC-550/555 (which uses 74LS123 monostables instead of a NE558).
-    The Apple //gs also recognizes a switch input 3, though this is
+    The Apple IIgs also recognizes a switch input 3, though this is
     placed on pin 9 of the internal connector rather than 16.
 
     The Apple IIe, IIc and IIgs also have an external DE-9 connector
@@ -73,6 +76,12 @@ void apple2_gameio_device::device_config_complete()
 	m_intf = dynamic_cast<device_a2gameio_interface *>(get_card_device());
 }
 
+void apple2_gameio_device::device_resolve_objects()
+{
+	if (m_intf != nullptr)
+		m_intf->m_connector = this;
+}
+
 void apple2_gameio_device::device_start()
 {
 }
@@ -119,7 +128,7 @@ READ_LINE_MEMBER(apple2_gameio_device::sw0_r)
 	if (m_intf != nullptr)
 		return m_intf->sw0_r();
 
-	return 0;
+	return m_sw_pullups ? 1 : 0;
 }
 
 READ_LINE_MEMBER(apple2_gameio_device::sw1_r)
@@ -127,7 +136,7 @@ READ_LINE_MEMBER(apple2_gameio_device::sw1_r)
 	if (m_intf != nullptr)
 		return m_intf->sw1_r();
 
-	return 0;
+	return m_sw_pullups ? 1 : 0;
 }
 
 READ_LINE_MEMBER(apple2_gameio_device::sw2_r)
@@ -135,7 +144,7 @@ READ_LINE_MEMBER(apple2_gameio_device::sw2_r)
 	if (m_intf != nullptr)
 		return m_intf->sw2_r();
 
-	return 0;
+	return m_sw_pullups ? 1 : 0;
 }
 
 READ_LINE_MEMBER(apple2_gameio_device::sw3_r)
@@ -143,7 +152,7 @@ READ_LINE_MEMBER(apple2_gameio_device::sw3_r)
 	if (m_intf != nullptr)
 		return m_intf->sw3_r();
 
-	return 0;
+	return m_sw_pullups ? 1 : 0;
 }
 
 WRITE_LINE_MEMBER(apple2_gameio_device::an0_w)
@@ -189,6 +198,7 @@ WRITE_LINE_MEMBER(apple2_gameio_device::strobe_w)
 
 device_a2gameio_interface::device_a2gameio_interface(const machine_config &mconfig, device_t &device)
 	: device_slot_card_interface(mconfig, device)
+	, m_connector(nullptr)
 {
 }
 

src/devices/bus/a2gameio/gameio.h

@@ -37,6 +37,10 @@ public:
 		set_fixed(false);
 	}
 
+	// configuration
+	void set_sw_pullups(bool enabled) { m_sw_pullups = enabled; }
+	bool has_sw_pullups() const { return m_sw_pullups; }
+
 	// standard options
 	static void default_options(device_slot_interface &slot);
 
@@ -65,11 +69,14 @@ public:
 protected:
 	// device-level overrides
 	virtual void device_config_complete() override;
+	virtual void device_resolve_objects() override;
 	virtual void device_start() override;
 
 private:
 	// selected device
 	device_a2gameio_interface *m_intf;
+
+	bool m_sw_pullups;
 };
 
 // ======================> device_a2gameio_interface
@@ -88,10 +95,10 @@ protected:
 	virtual u8 pdl1_r() { return 0; }
 	virtual u8 pdl2_r() { return 0; }
 	virtual u8 pdl3_r() { return 0; }
-	virtual DECLARE_READ_LINE_MEMBER(sw0_r) { return 0; }
-	virtual DECLARE_READ_LINE_MEMBER(sw1_r) { return 0; }
-	virtual DECLARE_READ_LINE_MEMBER(sw2_r) { return 0; }
-	virtual DECLARE_READ_LINE_MEMBER(sw3_r) { return 0; }
+	virtual DECLARE_READ_LINE_MEMBER(sw0_r) { return m_connector->has_sw_pullups() ? 1 : 0; }
+	virtual DECLARE_READ_LINE_MEMBER(sw1_r) { return m_connector->has_sw_pullups() ? 1 : 0; }
+	virtual DECLARE_READ_LINE_MEMBER(sw2_r) { return m_connector->has_sw_pullups() ? 1 : 0; }
+	virtual DECLARE_READ_LINE_MEMBER(sw3_r) { return m_connector->has_sw_pullups() ? 1 : 0; }
 
 	// optional output overrides
 	virtual DECLARE_WRITE_LINE_MEMBER(an0_w) { }
@@ -100,6 +107,9 @@ protected:
 	virtual DECLARE_WRITE_LINE_MEMBER(an3_w) { }
 	virtual DECLARE_WRITE_LINE_MEMBER(an4_w) { }
 	virtual DECLARE_WRITE_LINE_MEMBER(strobe_w) { }
+
+private:
+	apple2_gameio_device *m_connector;
 };
 
 // device type declaration

src/mame/drivers/mbc55x.cpp

@@ -362,6 +362,7 @@ void mbc55x_state::mbc55x(machine_config &config)
 	INPUT_MERGER_ANY_HIGH(config, "sioint").output_handler().set(m_pic, FUNC(pic8259_device::ir2_w));
 
 	APPLE2_GAMEIO(config, m_gameio, apple2_gameio_device::default_options, nullptr);
+	m_gameio->set_sw_pullups(true); // 3300 ohm pullups to 5.0V on pins 2-4 and 16
 
 	CENTRONICS(config, m_printer, centronics_devices, nullptr);
 	m_printer->busy_handler().set(FUNC(mbc55x_state::printer_busy_w)).invert(); // LS14 Schmitt trigger