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How To: Enable 1 Minute Penalties [SNES]


McMarkis

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Enable 1 Minute Penalties


Problem:
The SNES rom crashes when you try to modify penalties to be 1 minute, as the game developers never expected there to be 1 minute penalties.


Solution:
Modify the penalty length in the ROM and skip the problematic check for 0 or 1 if the penalty length is one minute.

Technical Details:

Similar to the "Defense Ctrl" code injection method, we have to swap out some of the existing code and insert a jump to new code that we create. This new code will be placed in the free space at the end of the 9E bank.

Problem Code:

image.png

Hijack Instruction before the problem code and run new code (One_Min_Pen)

image.png

Run new code to skip the compare if we know its a one minute penalty and continue like normal as if it was a 2 min penalty.

image.png

I have included the 1 min penalty rom to play around with or compare for differences if interested. Or you can download the tool and create your own ROM.

image.pngimage.png

https://github.com/Mhopkinsinc/NHL94SNESVault/releases

nhl94.sfc

Hex Version:

image.png

1) Change all the penalties from 02 minutes to 01 minutes.

Headerless ROM (.SFC)
ROM Offsets: (hex) 54C7,54E9,550B,552B,554B,556B,558C,55B1,55C9
Change:02 to 01

Headered ROM (.SMC)
ROM Offsets: (hex) 56C7,56E9,570B,572B,574B,576B,578C,57B1,57C9
Change:02 to 01

2) Hijack old code and point to the new code

Headerless ROM (.SFC)
ROM Offsets: (hex) F3417-F3419
Change:29 FF 00 to 4C 5B FB

Headered ROM (.SMC)
ROM Offsets: (hex) F3617-F3619
Change:29 FF 00 to 4C 5B FB

3) Insert new code that fixes the bug

Headerless ROM (.SFC)
ROM Offsets: (hex) F7B5B-F7B6D
Change: FF's to C9 01 04 F0 05 C9 01 0A D0 03 4C 21 B4 29 FF 00 4C 1A B4

Headered ROM (.SMC)
ROM Offsets: (hex) F7D5B-F7D6D
Change: FF's to C9 01 04 F0 05 C9 01 0A D0 03 4C 21 B4 29 FF 00 4C 1A B4

 

Edited by McMarkis
Updated, added Hex version so this can be done by hand
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