(MESS) apple3: improved interrupt generation and scanline timing [R. Belmont]

src/mess/drivers/apple3.c

@@ -52,7 +52,6 @@ static MACHINE_CONFIG_START( apple3, apple3_state )
 	MCFG_CPU_ADD("maincpu", M6502, 2000000)        /* 2 MHz */
 	MCFG_M6502_SYNC_CALLBACK(WRITELINE(apple3_state, apple3_sync_w))
 	MCFG_CPU_PROGRAM_MAP(apple3_map)
-	MCFG_CPU_PERIODIC_INT_DRIVER(apple3_state, apple3_interrupt, 192)
 	MCFG_QUANTUM_TIME(attotime::from_hz(60))
 
 	MCFG_MACHINE_RESET_OVERRIDE(apple3_state, apple3 )
@@ -61,7 +60,7 @@ static MACHINE_CONFIG_START( apple3, apple3_state )
 	MCFG_SCREEN_ADD("screen", RASTER)
 	MCFG_SCREEN_REFRESH_RATE(60)
 	MCFG_SCREEN_VBLANK_TIME(ATTOSECONDS_IN_USEC(2500)) /* not accurate */
-	MCFG_SCREEN_SIZE(280*2, 192)
+	MCFG_SCREEN_SIZE(280*2, 224)
 	MCFG_SCREEN_VISIBLE_AREA(0, (280*2)-1,0,192-1)
 	MCFG_SCREEN_UPDATE_DRIVER(apple3_state, screen_update_apple3)
 
@@ -70,6 +69,8 @@ static MACHINE_CONFIG_START( apple3, apple3_state )
 
 	MCFG_VIDEO_START_OVERRIDE(apple3_state, apple3 )
 
+	MCFG_TIMER_DRIVER_ADD_SCANLINE("scantimer", apple3_state, apple3_interrupt, "screen", 0, 1)
+
 	/* slot bus */
 	MCFG_A2BUS_BUS_ADD("a2bus", "maincpu", a2bus_intf)
 

src/mess/includes/apple3.h

@@ -73,7 +73,7 @@ public:
 	DECLARE_MACHINE_RESET(apple3);
 	DECLARE_VIDEO_START(apple3);
 	UINT32 screen_update_apple3(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
-	INTERRUPT_GEN_MEMBER(apple3_interrupt);
+	TIMER_DEVICE_CALLBACK_MEMBER(apple3_interrupt);
 	DECLARE_WRITE8_MEMBER(apple3_via_0_out_a);
 	DECLARE_WRITE8_MEMBER(apple3_via_0_out_b);
 	DECLARE_WRITE8_MEMBER(apple3_via_1_out_a);
@@ -95,6 +95,7 @@ public:
 	UINT8 *apple3_get_indexed_addr(offs_t offset);
 	TIMER_DEVICE_CALLBACK_MEMBER(apple3_c040_tick);
 	DECLARE_PALETTE_INIT(apple3);
+	void apple3_irq_update();
 
 	bool m_sync;
 	UINT8 m_indir_opcode;

src/mess/machine/apple3.c

@@ -4,22 +4,41 @@
 
     Apple ///
 
-
     VIA #0 (D VIA)
-        CA1:    1 if a cartridge is inserted, 0 otherwise
+	    CA1: IRQ from the MM58167 RTC
+    	CA2: 1 if key pressed, 0 otherwise
+    	CB1/CB2: connected to VBL
+ 
+		Port A: Environment register (all bits out)
+			bit 7: 1 for 1 MHz, 0 for 2 MHz
+			bit 6: 1 for I/O at C000-CFFF
+			bit 5: 1 to enable video 
+			bit 4: 1 to enable NMI/Reset 
+			bit 3: 1 to write-protect RAM in system bank C000-FFFF
+			bit 2: 1 to force primary stack at 0100-01FF
+			bit 1: 1 for primary ROM, 0 for secondary (Apple III doesn't have a secondary ROM, so this should always be '1' when bit 0 is)
+			bit 0: 1 to enable ROM in F000-FFFF
+ 
+		Port B: Zero page high 8 address bits, also MM58167 RTC register select (all bits out)
  
     VIA #1 (E VIA)
-        CA2:    1 if key pressed, 0 otherwise
+    	CA1: OR of all 4 slots' IRQ status
+    	CA2: SW1 (Open Apple key?)
+    	CB1: SW3/SCO
+    	CB2: SER
  
-    m_via_0_a: Environment register
+    	Port A:
-    	bit 7: 1 for 1 MHz, 0 for 2 MHz
+			bits 0-2: bank select for $2000-$9FFF range
-    	bit 6: 1 for I/O at C000-CFFF
+			bit 3: n/c
-    	bit 5: 1 to enable video 
+			bit 4: slot 4 IRQ (in)
-    	bit 4: 1 to enable NMI/Reset 
+			bit 5: slot 3 IRQ (in)
-    	bit 3: 1 to write-protect RAM in system bank C000-FFFF
+			bit 6: Apple II mode trap output (out)
-    	bit 2: 1 to force primary stack at 0100-01FF
+			bit 7: IRQ status (in) (0 = IRQ, 1 = no IRQ)
-    	bit 1: 1 for primary ROM, 0 for secondary (Apple III doesn't have a secondary ROM, so this should always be '1' when bit 0 is)
+ 
-    	bit 0: 1 to enable ROM in F000-FFFF
+		Port B:
+			bits 0-5: 6-bit audio DAC output
+			bit 6: screen blank
+			bit 7: OR of NMI from slots
  
 ***************************************************************************/
 
@@ -228,15 +247,13 @@ WRITE8_MEMBER(apple3_state::apple3_c0xx_w)
 	}
 }
 
-INTERRUPT_GEN_MEMBER(apple3_state::apple3_interrupt)
+TIMER_DEVICE_CALLBACK_MEMBER(apple3_state::apple3_interrupt)
 {
 	m_via_1->write_ca2((AY3600_keydata_strobe_r(machine()) & 0x80) ? 1 : 0);
 	m_via_1->write_cb1(machine().primary_screen->vblank()); 
 	m_via_1->write_cb2(machine().primary_screen->vblank());
 }
 
-
-
 UINT8 *apple3_state::apple3_bankaddr(UINT16 bank, offs_t offset)
 {
 	if (bank != (UINT16) ~0)
@@ -373,31 +390,35 @@ WRITE8_MEMBER(apple3_state::apple3_via_1_out_b)
 	apple3_via_out(&m_via_1_b, data);
 }
 
-WRITE_LINE_MEMBER(apple3_state::apple3_via_1_irq_func)
+void apple3_state::apple3_irq_update()
 {
-	m_via_1_irq = state;
 	if (m_via_1_irq || m_via_0_irq)
 	{
+//		printf("   asserting IRQ\n");
 		m_maincpu->set_input_line(M6502_IRQ_LINE, ASSERT_LINE);
+		m_via_1->write_pa7(0);	// this is active low
 	}
 	else
 	{
+//		printf("   clearing IRQ\n");
 		m_maincpu->set_input_line(M6502_IRQ_LINE, CLEAR_LINE);
+		m_via_1->write_pa7(1);
 	}
 }
 
+WRITE_LINE_MEMBER(apple3_state::apple3_via_1_irq_func)
+{
+//	printf("via 1 IRQ: %d\n", state);
+	m_via_1_irq = state;
+	apple3_irq_update();
+}
+
 
 WRITE_LINE_MEMBER(apple3_state::apple3_via_0_irq_func)
 {
+//	printf("via 0 IRQ: %d\n", state);
 	m_via_0_irq = state;
-	if (m_via_1_irq || m_via_0_irq)
+	apple3_irq_update();
-	{
-		m_maincpu->set_input_line(M6502_IRQ_LINE, ASSERT_LINE);
-	}
-	else
-	{
-		m_maincpu->set_input_line(M6502_IRQ_LINE, CLEAR_LINE);
-	}
 }
 
 MACHINE_RESET_MEMBER(apple3_state,apple3)