Here are some of my notes from adding a "Free Play" option to Blackbelt.
If you read my notes on Farfalla, this is a continuation of that effort.
Blackbelt is another 2 x 2764 ROM layout, similar to Farfalla. In fact, the steps are the same as for Farfalla, and the blocks of code to be patched are virtually identical.
Again, 0x6000 is unused in the ROM space, so it's a perfect place to put my revised code to add Free Play.
Disables "Coin Meter" check
Patch [07 FF] to [07 00] @0x240F (0x0C0F in Rom1 Bank2)
Disable credit = 0? check
Patch [0C 1F 22] to [1F 60 00] @0x2829 (0x0829 in Rom2 Bank2)
Return address: 0x282C
Prevent credit decrement less than 0
Patch to [0C 1F 22 A4 01] to [1F 60 18 C0 C0] @0x2866 (0x0866 in Rom2 Bank2)
Return address: 0x286B
PinMAME tested – OK 12 February 2011
Game tested – OK 12 February 2011
David Gersic firstname.lastname@example.org
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