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Steveyzerman

NHL'97 How do you edit the checksum

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I need help editing the checksum or bypassing the checksum, please help.

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Refer to this post.

Note, the checksum routine is bigger in 97 than 94 (used in the example), and the refering offset is at Hex 768 and not Hex 302.

Ignoring the above, and if you want the you want the quick fix, find the last occurence of 4E71 and change it to 6602 (from memory).... I recommend you follow the stesp above though/

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Refer to this post.

Note, the checksum routine is bigger in 97 than 94 (used in the example), and the refering offset is at Hex 768 and not Hex 302.

Ignoring the above, and if you want the you want the quick fix, find the last occurence of  4E71 and change it to 6602 (from memory).... I recommend you follow the stesp above though/

I tried that, but it did not work so well, Do you know the exact bin offset

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I tried that, but it did not work so well, Do you know the exact bin offset

Hmmmm.... it should work if done properly. Oh well, here is another way....

Take a clean 97 rom (or atleast don't use the same rom you used to test the method above).

Goto 1E253C

Change the value 6602 to 4E71

I got it the wrong way around in my earlier post! :D

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Hey that worked, cheers!

How did you know that anyway, how do you know about checksums of different games.

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Hey that worked, cheers!

How did you know that anyway, how do you know about checksums of different games.

I simply took some old game genie master codes for a few of the early NHL roms in the series. Working back what they did (they effiectively rom hack bytes dynamically when the game loads), all the master codes (needed to have other codes work) changed the checksum routine bytes 6602 to 4E71.

This works for all EA games I've checked except for NHL & NFL 98, which have no checksum routines... and from that I learnt who to remove the checksum in all games (as per my linked topic instructions).

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does it work with the Fifa series

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does it work with the Fifa series

Well I just checked the Genesis FIFA 95 and 98 and both have the common EA checksum routine as used in the NHL series.

Simply do a find for 6602, goto the last occurence of it and change it to 4E71 (or remove it completely as in my more detailed instructions to make it load marginally quicker. ;))

I did a quick name edit test after doing so, and can confirm it will load. :D

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Thanks :D

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I have done the same thing too (game genie "master codes") also when hacking Madden roms. If you don't want to convert the Game Genie text to hex in your head, there is a Game Genie Code converter out there. Those codes come in handy.

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Greetings!  I just a read a post you made a while back regarding FIFA 95 and was hoping you could help me.  I tried to follow your advice but I am a complete beginner in regards to Hex editing.  Waaaaaaaaaaayyy back in 2005 you said:

 

Quote
Well I just checked the Genesis FIFA 95 and 98 and both have the common EA checksum routine as used in the NHL series.

Simply do a find for 6602, goto the last occurence of it and change it to 4E71 (or remove it completely as in my more detailed instructions to make it load marginally quicker. ;))

I did a quick name edit test after doing so, and can confirm it will load. :D

How would i do this?

I have a trial version of Hex Editor Zero and was also trying to use the Free Online Hex Editor from - https://www.onlinehexeditor.com/ but when i search for 6602 I can no results.

You have me pretty excited as I am trying to find a way to edit the players names/attributes etc and if you can get me closer to this goal I would be eternally grateful.

 

regards.

 

shadowmeister

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6 hours ago, shadowmeister said:

Greetings!  I just a read a post you made a while back regarding FIFA 95 and was hoping you could help me.  I tried to follow your advice but I am a complete beginner in regards to Hex editing.  Waaaaaaaaaaayyy back in 2005 you said:

 

How would i do this?

I have a trial version of Hex Editor Zero and was also trying to use the Free Online Hex Editor from - https://www.onlinehexeditor.com/ but when i search for 6602 I can no results.

You have me pretty excited as I am trying to find a way to edit the players names/attributes etc and if you can get me closer to this goal I would be eternally grateful.

 

regards.

 

shadowmeister

Three is a good free hex editor called "HxD" (for windows), if you don't want to use that trial software or online editor.

(One small issue with hxd is you need to read the options carefully when doing a search as it tends to default to searching as text, not hex, and I think the "go to address" defaults to decimal not hex.. Which just aren't the defaults I would expect)

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