abc80x: Implemented option ROM opcode fetch thru character RAM. [Curt Coder]

src/mame/drivers/abc80x.cpp

@@ -379,6 +379,68 @@ void abc806_state::bankswitch()
 }
 
 
+//-------------------------------------------------
+//  m1_r - opcode read
+//-------------------------------------------------
+
+READ8_MEMBER( abc800_state::m1_r )
+{
+	if (offset >= 0x7800 && offset < 0x8000)
+	{
+		if (!m_fetch_charram)
+		{
+			m_fetch_charram = 1;
+			bankswitch();
+		}
+
+		return m_rom->base()[0x7800 | (offset & 0x7ff)];
+	}
+
+	if (m_fetch_charram)
+	{
+		m_fetch_charram = 0;
+		bankswitch();
+	}
+
+	return m_maincpu->space(AS_PROGRAM).read_byte(offset);
+}
+
+READ8_MEMBER( abc800c_state::m1_r )
+{
+	if (offset >= 0x7c00 && offset < 0x8000)
+	{
+		if (!m_fetch_charram)
+		{
+			m_fetch_charram = 1;
+			bankswitch();
+		}
+
+		return m_rom->base()[0x7c00 | (offset & 0x3ff)];
+	}
+
+	if (m_fetch_charram)
+	{
+		m_fetch_charram = 0;
+		bankswitch();
+	}
+
+	return m_maincpu->space(AS_PROGRAM).read_byte(offset);
+}
+
+READ8_MEMBER( abc802_state::m1_r )
+{
+	if (m_lrs)
+	{
+		if (offset >= 0x7800 && offset < 0x8000)
+		{
+			return m_rom->base()[0x7800 | (offset & 0x7ff)];
+		}
+	}
+
+	return m_maincpu->space(AS_PROGRAM).read_byte(offset);
+}
+
+
 //-------------------------------------------------
 //  mai_r - memory bank map read
 //-------------------------------------------------
@@ -425,6 +487,16 @@ WRITE8_MEMBER( abc806_state::mao_w )
 //  ADDRESS MAPS
 //**************************************************************************
 
+//-------------------------------------------------
+//  ADDRESS_MAP( abc800_m1 )
+//-------------------------------------------------
+
+void abc800_state::abc800_m1(address_map &map)
+{
+	map(0x0000, 0xffff).r(this, FUNC(abc800_state::m1_r));
+}
+
+
 //-------------------------------------------------
 //  ADDRESS_MAP( abc800c_mem )
 //-------------------------------------------------
@@ -466,11 +538,11 @@ ADDRESS_MAP_END
 //-------------------------------------------------
 
 ADDRESS_MAP_START(abc800_state::abc800m_mem)
-	ADDRESS_MAP_UNMAP_HIGH
+	map.unmap_value_high();
-	AM_RANGE(0x0000, 0x3fff) AM_RAM AM_SHARE("video_ram")
+	map(0x0000, 0x3fff).ram().share("video_ram");
-	AM_RANGE(0x4000, 0x77ff) AM_ROM
+	map(0x4000, 0x77ff).rom();
-	AM_RANGE(0x7800, 0x7fff) AM_RAM AM_SHARE("char_ram")
+	map(0x7800, 0x7fff).ram().share("char_ram");
-	AM_RANGE(0x8000, 0xffff) AM_RAM
+	map(0x8000, 0xffff).ram();
 ADDRESS_MAP_END
 
 
@@ -1024,6 +1096,7 @@ MACHINE_CONFIG_START(abc800c_state::abc800c)
 	// basic machine hardware
 	MCFG_CPU_ADD(Z80_TAG, Z80, ABC800_X01/2/2)
 	MCFG_Z80_DAISY_CHAIN(abc800_daisy_chain)
+	MCFG_CPU_OPCODES_MAP(abc800_m1)
 	MCFG_CPU_PROGRAM_MAP(abc800c_mem)
 	MCFG_CPU_IO_MAP(abc800c_io)
 
@@ -1099,6 +1172,7 @@ MACHINE_CONFIG_START(abc800m_state::abc800m)
 	// basic machine hardware
 	MCFG_CPU_ADD(Z80_TAG, Z80, ABC800_X01/2/2)
 	MCFG_Z80_DAISY_CHAIN(abc800_daisy_chain)
+	MCFG_CPU_OPCODES_MAP(abc800_m1)
 	MCFG_CPU_PROGRAM_MAP(abc800m_mem)
 	MCFG_CPU_IO_MAP(abc800m_io)
 
@@ -1174,6 +1248,7 @@ MACHINE_CONFIG_START(abc802_state::abc802)
 	// basic machine hardware
 	MCFG_CPU_ADD(Z80_TAG, Z80, ABC800_X01/2/2)
 	MCFG_Z80_DAISY_CHAIN(abc800_daisy_chain)
+	MCFG_CPU_OPCODES_MAP(abc800_m1)
 	MCFG_CPU_PROGRAM_MAP(abc802_mem)
 	MCFG_CPU_IO_MAP(abc802_io)
 
@@ -1250,6 +1325,7 @@ MACHINE_CONFIG_START(abc806_state::abc806)
 	// basic machine hardware
 	MCFG_CPU_ADD(Z80_TAG, Z80, ABC800_X01/2/2)
 	MCFG_Z80_DAISY_CHAIN(abc800_daisy_chain)
+	MCFG_CPU_OPCODES_MAP(abc800_m1)
 	MCFG_CPU_PROGRAM_MAP(abc806_mem)
 	MCFG_CPU_IO_MAP(abc806_io)
 

src/mame/includes/abc80x.h

@@ -117,6 +117,7 @@ public:
 	void bankswitch();
 	void clock_cassette(int state);
 
+	virtual DECLARE_READ8_MEMBER( m1_r );
 	DECLARE_READ8_MEMBER( pling_r );
 	DECLARE_WRITE8_MEMBER( hrs_w );
 	DECLARE_WRITE8_MEMBER( hrc_w );
@@ -128,7 +129,9 @@ public:
 	DECLARE_WRITE_LINE_MEMBER( sio_rtsb_w );
 
 	// memory state
-	int m_fetch_charram;        // opcode fetched from character RAM region (0x7800-0x7fff)
+	bool m_fetch_charram;        // opcode fetched from character RAM region (0x7800-0x7fff)
+	uint16_t m_char_ram_start;
+	uint16_t m_char_ram_mask;
 
 	// sound state
 	int m_pling;
@@ -150,6 +153,7 @@ public:
 	// timers
 	emu_timer *m_ctc_timer;
 	emu_timer *m_cassette_timer;
+	void abc800_m1(address_map &map);
 	void abc800c_io(address_map &map);
 	void abc800m_io(address_map &map);
 	void abc800m_mem(address_map &map);
@@ -205,6 +209,7 @@ public:
 	offs_t translate_trom_offset(offs_t offset);
 	void hr_update(bitmap_rgb32 &bitmap, const rectangle &cliprect);
 
+	DECLARE_READ8_MEMBER( m1_r ) override;
 	DECLARE_READ8_MEMBER( char_ram_r );
 	DECLARE_PALETTE_INIT( abc800c );
 	void abc800c(machine_config &config);
@@ -239,6 +244,7 @@ public:
 
 	void bankswitch();
 
+	DECLARE_READ8_MEMBER( m1_r ) override;
 	DECLARE_READ8_MEMBER( pling_r );
 	DECLARE_WRITE_LINE_MEMBER( lrs_w );
 	DECLARE_WRITE_LINE_MEMBER( mux80_40_w );