Here are some of my notes from adding a "Free Play" option to Devil Riders.
If you read my notes on Farfalla, this is a continuation of that effort.
This is almost identical to Farfalla and Blackbelt. Two 2764 ROMs, with nothing in Rom1 Bank4 (0x6000). By replacing Rom1 Bank4 with my own image data, containing the Free Play revisions to the game, and some patches that should look very familiar by now, Devil Riders is done and ready for testing.
Disables "Coin Meter" check
Patch [07 FF] to [07 00] @0x2407 (0x0C07 in ROM1 image)
Disable credit = 0? check
Patch [0C 1F 22] to [1F 60 00] @0x27CE (0x0FCE in ROM1 image)
Return address: 0x27D1
Prevent credit decrement less than 0
Patch to [0C 1F 22 A4 01] to [1F 60 18 C0 C0] @0x280B (0x080B in ROM2 image)
Return address: 0x2810
PinMAME tested – OK 24 February 2011
Game tested – Not Tested Yet
David Gersic email@example.com
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