[Oct/11/98]
 
 SPEED BALL  1987  DESYSTEM
 
 CPU Z80
 
 SOUND Z80 & YM3812
 
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 [MAME]
 
 Speed Ball
 
 Memory map
 
 Z80 MAIN CPU
 0000-7fff ROM 1 32k
 8000-dbff ROM 2 data
 dc00-dfff for both CPU&SOUND (Shared)
 e000-e1ff Video RAM background tiles 16*16 (2 bytes: 1 for tile char + 1 for color)
 e800-efff Video RAM characters 32*32 (2 bytes: 1 for char and 1 for color)
 f000-feff RAM
 ff00-ffff Sprites (64 total: four bytes to one)
 
 in:
 00	DSW ONE
 10	DSW TWO
 20	IN1  JOY 1 STATUS & COIN & START
 30	IN2  JOY 2 STATUS & TILT
 
 out:
 40	????
 50	????  maybe VSYNC ????
 
  ======================================================================
 
 Z80 SOUND
 0000-7fff ROM
 dc00-dfff shared with MAIN CPU
 f000-dfff RAM
 
 out:
 00	YM3812 control
 01	YM3812 data
 20	??
 
  ======================================================================
 
   Colors :   2 bits for foreground characters =  4 colors * 16 palettes
 	     4 bits for background tiles      = 16 colors * 16 palettes
 	     4 bits for sprites	       = 16 colors * 16 palettes
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