some support for extended sprite addressing used by cybar120

src/devices/video/ppu2c0x.h

@@ -125,6 +125,7 @@ public:
 	virtual void read_sprite_plane_data(int address);
 	virtual void make_sprite_pixel_data(uint8_t &pixel_data, int flipx);
 	virtual void draw_sprite_pixel(int sprite_xpos, int color, int pixel, uint8_t pixel_data, bitmap_ind16& bitmap);
+	virtual void read_extra_sprite_bits(int sprite_index);
 
 	void draw_sprites( uint8_t *line_priority );
 	void render_scanline();
@@ -216,6 +217,7 @@ protected:
 	// used in rendering
 	uint8_t m_planebuf[2];
 	int                         m_scanline;         /* scanline count */
+	std::unique_ptr<uint8_t[]>  m_spriteram;           /* sprite ram */
 
 private:
 	static constexpr device_timer_id TIMER_HBLANK = 0;
@@ -226,7 +228,6 @@ private:
 	inline void writebyte(offs_t address, uint8_t data);
 
 	std::unique_ptr<bitmap_ind16>                m_bitmap;          /* target bitmap */
-	std::unique_ptr<uint8_t[]>  m_spriteram;           /* sprite ram */
 	std::unique_ptr<pen_t[]>    m_colortable;          /* color table modified at run time */
 	std::unique_ptr<pen_t[]>    m_colortable_mono;     /* monochromatic color table modified at run time */
 

src/devices/video/ppu2c0x_vt.cpp

@@ -230,10 +230,21 @@ void ppu_vt03_device::draw_tile_pixel(uint8_t pix, int color, uint16_t back_pen,
 	}
 }
 
+void ppu_vt03_device::read_extra_sprite_bits(int sprite_index)
+{
+	m_extra_sprite_bits = (m_spriteram[sprite_index + 2] & 0x1c) >>2;
+}
+
+uint8_t ppu_vt03_device::get_speva2_speva0()
+{
+	return m_extra_sprite_bits;
+}
+
 void ppu_vt03_device::set_2010_reg(uint8_t data)
 {
 	/*  7   : COLCOMP
-		6,5 : UNUSED
+		6   : UNUSED (8bpp enable on VT09?)
+		5   : UNUSED
 		4   : BKEXTEN
 		3   : SPEXTEN
 		2   : SP16EN

src/devices/video/ppu2c0x_vt.h

@@ -42,6 +42,7 @@ public:
 	virtual void read_sprite_plane_data(int address) override;
 	virtual void make_sprite_pixel_data(uint8_t &pixel_data, int flipx) override;
 	virtual void draw_sprite_pixel(int sprite_xpos, int color, int pixel, uint8_t pixel_data, bitmap_ind16& bitmap) override;
+	virtual void read_extra_sprite_bits(int sprite_index) override;
 
 	virtual void device_start() override;
 	virtual void device_reset() override;
@@ -51,6 +52,7 @@ public:
 
 	uint8_t get_va34();
 	uint8_t get_m_read_bg4_bg3();
+	uint8_t get_speva2_speva0();
 
 private:
 	devcb_read8 m_read_bg;
@@ -62,6 +64,7 @@ private:
 	int m_va34;
 
 	uint8_t m_extplanebuf[2];
+	uint8_t m_extra_sprite_bits;
 
 	palette_device *m_palette;
 

src/mame/drivers/nes_vt.cpp

@@ -14,7 +14,9 @@
   VT02 - banking scheme to access 32MB, Dual APU with PCM support
   VT03 - above + 4bpp sprite / bg modes, enhanced palette
   
-  VT08 - 8bpp or direct colour modes?
+  VT08 - ?
+
+  VT09 - 8bpp or direct colour modes?
   
   VT16 - ?
   VT18 - ?
@@ -374,6 +376,17 @@ int nes_vt_state::calculate_real_video_address(int addr, int extended, int readt
 			extended = 0;
 		}
 	}
+	else if (readtype == 1)
+	{
+		if (m_ppu->get_201x_reg(0x0) & 0x08)
+		{
+			extended = 1;
+		}
+		else
+		{
+			extended = 0;
+		}
+	}
 
 	/*
 	Calculating TVA17 - TVA10
@@ -517,8 +530,10 @@ int nes_vt_state::calculate_real_video_address(int addr, int extended, int readt
 			break;
 
 		case 1: // sprite display
-			is4bpp = m_ppu->get_201x_reg(0x0) & 0x04;
+			is4bpp = m_ppu->get_201x_reg(0x0) & 0x04; // 16 colors or 16-pixel wide (both adjust the read)
-			// todo (need something using it to test)
+
+			eva2_eva0 |= m_ppu->get_speva2_speva0();			
+			
 			break;
 
 		case 2: // CPU R/W access
@@ -526,7 +541,7 @@ int nes_vt_state::calculate_real_video_address(int addr, int extended, int readt
 			break;
 		}
 
-		finaladdr = ((m_410x[0x0] & 0x0F) << 21) | (va17_va10 << 13) | (eva2_eva0 << 10) | (addr & 0x03ff);
+		finaladdr = ((m_410x[0x0] & 0x0f) << 21) | (va17_va10 << 13) | (eva2_eva0 << 10) | (addr & 0x03ff);
 
 		if (is4bpp)
 			finaladdr = ((finaladdr &~0xf) << 1) | (va34 << 4) | (finaladdr & 0xf);