ROM Hack Hacking in Supercard saving

[i-link]

i tried changing the values in the saving after comparing with 2 saves, after confirm everything, i change 2 address and i save
after that i put the file back into the SD card and start to run the game, the game say file corrupted, how come?

i can confirm that my address is correct cause i tried that single game abt 4 -5 times, the saving different with different values in the same address only, using hex workshop i convert all the value that i want to hex and replace and save.

anyone can telll me y?

 

[davr]

most likely the game save uses some sort of checksum, and if you change any of the game data, you will also need to update the checksum. This involves: A) finding the checksum in the save file B) figuring out what method they are using to calculate the checksum C) after hacking the save, re-calculate the checksum using the discovered method.

 

[kelvinate]

Usually What I found in game saves as well is that there is a backup save somewhere down the save files which is the same. You will need to change both the first save as well as the backup save.

Anyidea on how to find the checksum? thats the single hardest thing to find in the save file.

 

[FAST6191]

The checksum is usually included within the file (do the usual save, move on space/fire one bullet....) and then check.
You will get the obvious drop in one number for the loss of a bullet/movement but there will also be another change: this is the checksum. (You might want to repeat this a few times just to make sure)

Now for the hard part: the checksum can be anything (bytesum, some crc variant, basic parity and does not have to be straightfoward (mathematical aplications to checksum or multiple checksums spread over multiple parts) and it also will not encompass the whole file.
Basically you have two options:
find a person who is willing to disassemble the rom and hack it (the only really viable method)
Get loads of saves and try to figure out the sum (snowballs chance in hell applies here).

 

[i-link]

hmm, i heard of the checksum but i just can't figure out which is which anyone can help?
save 1 time 18hr 07min 06sec

2F B93B 001E 001C 3327 2F29 3800 0006 002B 0800 004D 0300 0000 77A2

save 2 time 18hr 07min 14sec

00 BB3B 001E 001C 3327 2F29 3800 0006 002B 0800 004D 0300 0033 2593

save 3 time 18hr 06min 24sec

03 AF3B 001E 001C 3327 2F29 3800 0006 002B 0800 004D 0300 00AD 5B4B

i notice those in bold change but i can't figure out how to calculate the time, anyone can help? the others like gold i figure out the address, items everything. except the time,

and if possible anyone can help me calculate the checksum?

btw this game is rocket slime

 

[i-link]

sorry pls ignore the top msg i got some other stuff that change.. i get another set of saving!!!

 

[i-link]

save 1 time 18hrs 07min 06sec

2F B93B 001E 001C 3327 2F29 3800 0006 002B 0800 004D 0300 0000 77A2

save 2 time 18hrs 07min 14sec

00 BB3B 001E 001C 3327 2F29 3800 0006 002B 0800 004D 0300 0033 2593

save 3 time 18hrs 07min 21sec

A5 BC3B 001E 001C 3327 2F29 3800 0006 002B 0800 004D 0300 0033 B6E5

these saving only have time change

anyone can help? with the address for time and the checksum?

 

[nerd1]

what you need is a trainer or learn to dissemble the game

 

[i-link]

trainer? how to dissemble the game?
is it the same as im using hex workshop?