Directly from schematics.. MISSILE COMMAND --------------- HEX R/W D7 D6 D5 D4 D3 D2 D2 D0 function ---------+-----+------------------------+------------------------ 0000-01FF R/W D D D D D D D D 512 bytes working ram 0200-05FF R/W D D D D D D D D 3rd color bit region of screen ram. 0600-063F R/W D D D D D D D D More working ram. 06F0-3FFF R/W D D D D D D D D 2-color bit region of screen ram. ---------+-----+------------------------+------------------------ 4000-400F R/W D D D D D D D D POKEY ports. 4800 R D Right coin 4800 R D Center coin 4800 R D Left coin 4800 R D 1 player start 4800 R D 2 player start 4800 R D 2nd player left fire(cocktail) 4800 R D 2nd player center fire " 4800 R D 2nd player right fire " ---------+-----+------------------------+------------------------ 4800 R D D D D Horiz trackball displacement if ctrld=high. 4800 R D D D D Vert trackball displacement if ctrld=high. ---------+-----+------------------------+------------------------ 4800 W D Unused ?? 4800 W D screen flip 4800 W D left coin counter 4800 W D center coin counter 4800 W D right coin counter 4800 W D 2 player start LED. 4800 W D 1 player start LED. 4800 W D CTRLD, 0=read switches, 1= read trackball. ---------+-----+------------------------+------------------------ 4900 R D VBLANK read 4900 R D Self test switch input. 4900 R D SLAM switch input. 4900 R D Horiz trackball direction input. 4900 R D Vert trackball direction input. 4900 R D 1st player left fire. 4900 R D 1st player center fire. 4900 R D 1st player right fire. ---------+-----+------------------------+------------------------ 4A00 R D D D D D D D D Option switches. 4B00-4B07 W D D D D Color RAM. 4C00 W Watchdog. 4D00 W Interrupt acknowledge. ---------+-----+------------------------+------------------------ 5000-7FFF R D D D D D D D D Program. ---------+-----+------------------------+------------------------