text: /*******************************************************************************
  
       Nova 2001 - Video Description:
       --------------------------------------------------------------------------
  
       Foreground Playfield Chars (static)
          character code index from first set of chars
       Foreground Playfield color modifier RAM
          Char colors are normally taken from the first set of 16,
          This is the pen for "color 1" for this tile (from the first 16 pens)
  
       Background Playfield Chars (scrolling)
          character code index from second set of chars
       Foreground Playfield color modifier RAM
          Char colors are normally taken from the second set of 16,
          This is the pen for "color 1" for this tile (from the second 16 pens)
       (Scrolling in controlled via the 8910 A and B port outputs)
  
       Sprite memory is made of 32 byte records:
  
          Sprite+0, 0x80 = Sprite Bank
          Sprite+0, 0x7f = Sprite Character Code
          Sprite+1, 0xff = X location
          Sprite+2, 0xff = Y location
          Sprite+3, 0x20 = Y Flip
          Sprite+3, 0x10 = X Flip
          Sprite+3, 0x0f = pen for "color 1" taken from the first 16 colors
      Sprite+3, 0x80
      Sprite+3, 0x40
  
          All the rest are unknown and/or uneccessary.
  
  *******************************************************************************/
  
  #include "driver.h"
  
  UINT8 *nova2001_videoram2, *nova2001_colorram2;
  
  static tilemap *bg_tilemap, *fg_tilemap;
  
  PALETTE_INIT( nova2001 )
  {
  	int i,j;
  
  
  	for (i = 0;i < machine->drv->total_colors;i++)
  	{
  		int intensity,r,g,b;
  
  
  		intensity = (*color_prom >> 0) & 0x03;
  		/* red component */
  		r = (((*color_prom >> 0) & 0x0c) | intensity) * 0x11;
  		/* green component */
  		g = (((*color_prom >> 2) & 0x0c) | intensity) * 0x11;
  		/* blue component */
  		b = (((*color_prom >> 4) & 0x0c) | intensity) * 0x11;
  
  		palette_set_color(machine,i,MAKE_RGB(r,g,b));
  		color_prom++;
  	}
  
  	/* Color #1 is used for palette animation.          */
  
  	/* To handle this, color entries 0-15 are based on  */
  	/* the primary 16 colors, while color entries 16-31 */
  	/* are based on the secondary set.                  */
  
  	/* The only difference among 0-15 and 16-31 is that */
  	/* color #1 changes each time */
  
  	for (i = 0;i < 16;i++)
  	{
  		for (j = 0;j < 16;j++)
  		{
  			if (j == 1)
  			{
  				colortable[16*i+1] = i;
  				colortable[16*i+16*16+1] = i+16;
  			}
  			else
  			{
  				colortable[16*i+j] = j;
  				colortable[16*i+16*16+j] = j+16;
  			}
  		}
  	}
  }
  
  WRITE8_HANDLER( nova2001_videoram_w )
  {
  	videoram[offset] = data;
  	tilemap_mark_tile_dirty(bg_tilemap, offset);
  }
  
  WRITE8_HANDLER( nova2001_colorram_w )
  {
  	colorram[offset] = data;
  	tilemap_mark_tile_dirty(bg_tilemap, offset);
  }
  
  WRITE8_HANDLER( nova2001_videoram2_w )
  {
  	nova2001_videoram2[offset] = data;
  	tilemap_mark_tile_dirty(fg_tilemap, offset);
  }
  
  WRITE8_HANDLER( nova2001_colorram2_w )
  {
  	nova2001_colorram2[offset] = data;
  	tilemap_mark_tile_dirty(fg_tilemap, offset);
  }
  
  WRITE8_HANDLER( nova2001_scroll_x_w )
  {
  	tilemap_set_scrollx(bg_tilemap, 0, data - (flip_screen ? 0 : 7));
  }
  
  WRITE8_HANDLER( nova2001_scroll_y_w )
  {
  	tilemap_set_scrolly(bg_tilemap, 0, data);
  }
  
  WRITE8_HANDLER( nova2001_flipscreen_w )
  {
  	if (flip_screen != (~data & 0x01))
  	{
  		flip_screen_set(~data & 0x01);
  		tilemap_mark_all_tiles_dirty(ALL_TILEMAPS);
  	}
  }
  
  static TILE_GET_INFO( get_bg_tile_info )
  {
  	int code = videoram[tile_index];
  	int color = colorram[tile_index] & 0x0f;
  
  	SET_TILE_INFO(1, code, color, 0);
  }
  
  static TILE_GET_INFO( get_fg_tile_info )
  {
  	int code = nova2001_videoram2[tile_index];
  	int color = nova2001_colorram2[tile_index] & 0x0f;
  
  	SET_TILE_INFO(0, code, color, 0);
  }
  
  VIDEO_START( nova2001 )
  {
  	bg_tilemap = tilemap_create(get_bg_tile_info, tilemap_scan_rows,
  		TILEMAP_TYPE_PEN, 8, 8, 32, 32);
  
  	fg_tilemap = tilemap_create(get_fg_tile_info, tilemap_scan_rows,
  		TILEMAP_TYPE_PEN, 8, 8, 32, 32);
  
  	tilemap_set_transparent_pen(fg_tilemap, 0);
  }
  
  static void draw_sprites(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect )
  {
  	int offs;
  
  	for (offs = 0;offs < spriteram_size;offs += 32)
  	{
  		int flipx = spriteram[offs+3] & 0x10;
  		int flipy = spriteram[offs+3] & 0x20;
  		int sx = spriteram[offs+1];
  		int sy = spriteram[offs+2];
  
  		if (flip_screen)
  		{
  			sx = 240 - sx;
  			sy = 240 - sy;
  			flipx = !flipx;
  			flipy = !flipy;
  		}
  
  		drawgfx(bitmap,machine->gfx[2 + ((spriteram[offs+0] & 0x80) >> 7)],
  			spriteram[offs+0] & 0x7f,
  			spriteram[offs+3] & 0x0f,
  			flipx,flipy,
  			sx,sy,
  			cliprect,TRANSPARENCY_PEN,0);
  	}
  }
  
  VIDEO_UPDATE( nova2001 )
  {
  	tilemap_draw(bitmap, cliprect, bg_tilemap, 0, 0);
  	draw_sprites(machine, bitmap, cliprect);
  	tilemap_draw(bitmap, cliprect, fg_tilemap, 0, 0);
  	return 0;
  }
  