User:Andlabs/Racing Hero

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Andlabs
Developers: Sega, Aicom Publisher: Sega Platform: Arcade (Sega X Board) Released internationally: TODO

Debugging Functionality

Prerequisites

Before we can access the debug features, we have to build a custom version of MAME with a simple change.

Go into src/mame/drivers/segaxbd.c and locate the block of code surrounded by

//**************************************************************************
//  GENERIC PORT DEFINITIONS
//**************************************************************************

static INPUT_PORTS_START( xboard_generic )
	...
INPUT_PORTS_END

Within that block should be a line that says

	PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_UNKNOWN )    // button? not used by any game we have

Change it to

	PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_BUTTON3 ) PORT_NAME("Debug Mode")

If all goes well, if you start MAME and open Racing Hero, you'll find that your Button 3 key (by default, the spacebar) will be assigned to a new button, "Debug Mode". You can change it if you want; I'll be referring to this button as "Debug Mode" from now on.

You will also need to assign keys to the "Suicide" and "Move to Center" buttons.

To do: Verify that all this works with A. B. Cop as well

Getting In

Now that we can access the debugging functionality, start MAME with the debugger.

Whether the debugging features are enabled is also dependent on bit 3 of byte $3FFFE in the main CPU ROM. By default, this byte is set to $E7, leaving bit 3 unset. We'll need to set it on with the debugger:

maincpu.ob@3FFFE = 0xEF
go

To do: The other unset bit, 4, seems to be a region switch; there's no racheroj (yet), though... There is abcop and abcopj, so I wouldn't be surprised, but its region bit seems to be different from what the code claims it is

Now we can finally begin debugging. Press both 1P Start and Debug Mode at the same time. The game should pause, and the text PAUSE should appear on the bottom-left corner of the screen. Press both buttons again to unpause.