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Memory Map

The following is a memory map that was generated based on the MAME source code (.180).  This information is only as accurate as the MAME driver is.  If you see any errors, please let me know what that error is.
 
The Memory Area is related to where the information is from (CPU, Sound Board, etc..), and it may also reflect what it has in common with other hardware.
Head On (Irem, 1979)
Memory Area:m15_main
Address RangeLengthFunctionDescription
0x0000-0x02FF768RAM, Sharedmemory (/* scratch ram */)
0x1000-0x33FF9216ROM, Sharedrom
0x4000-0x43FF1024RAM, Sharedvideoram
0x4800-0x4BFF1024RAM Write, Sharedm10_colorram_w, colorram (/* foreground colour */)
0x5000-0x57FF2048RAM Write, Sharedm15_chargen_w, chargen (/* background ????? */)
0xA0001Read PortP2
0x0003UnusedActive High
0x0004Button 1Active High
0x0008Joystick UpActive High
0x0010Joystick DownActive High
0x0020Joystick LeftActive High
0x0040Joystick RightActive High
0x0080UnknownActive High
0xA1001Writem15_a100_w (/* sound writes ???? */)
0xA2001Read PortDSW
0xA3001Read PortP1
0x0001Start 1Active High
0x0002Start 2Active High
0x0004Button 1Active High
0x0008Joystick UpActive High
0x0010Joystick DownActive High
0x0020Joystick LeftActive High
0x0040Joystick RightActive High
0x0080UnknownActive High
0xA4001Writem15_ctrl_w (/* sound, flip screen */)
0xFC00-0xFFFF1024ROM(/* for the reset / interrupt vectors */)
 

ROM Map for this game

 
This is the ROM map for the game.  This should tell you what address the ROM is at, how big it is, what it's used for.   
Memory Area:maincpu
Address RangeLengthLabel/LocationDescription
0x1000-0x13FF1024e1.9aCRC(05da5265) (Fluke: 7319)
0x1400-0x17FF1024e2.9bCRC(dada26a8) (Fluke: 6CE7)
0x1800-0x1BFF1024e3.9cCRC(61ff24f5) (Fluke: DE25)
0x1C00-0x1FFF1024e4.9dCRC(ce4c5a67) (Fluke: 0F18)
0x2000-0x23FF1024e5.9fCRC(b5232439) (Fluke: 5C5C)
0x2400-0x27FF1024e6.9gCRC(99acd1a6) (Fluke: 31C0)
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