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PostPosted: Wed Sep 02, 2015 4:20 am 
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OK I got my FDSStick so I tried purifying Yume Koujou. It seems you can zero out all 6 bytes in the SAV-DAT file. The last two bytes will be written to when you save anyway ($5A, $A5 when I finished the first world with Imajin and saved), but I have no idea what they are for. Maybe a checksum or something?

Anyway FDSExplorer doesn't seem to be able to edit files. It can only add or remove files entirely. I used a normal hex editor and searched for the hex string in the save file to find it and edit it. But is there anyway to calculate the address in the .fds image to the addresses on the disk used by the Famicom?


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PostPosted: Wed Sep 02, 2015 7:41 am 
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Do the $5A $A5 values ever change?

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PostPosted: Wed Sep 02, 2015 3:02 pm 
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I will keep an eye on them next time I beat a chapter. Annoyingly the only way to save seems to be to get a Game Over according to the manual. I discovered a suicide trick (on pause screen: con II A+B+UP) but you tend to get lots of extra lives from slot machines, so it takes some time.


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PostPosted: Thu Sep 03, 2015 2:31 pm 
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Hi,

I've been using Loopy's FDSStick to do dumps of some sealed games. I have gotten a fair amount so far as I want to eventually get nice clean RAW and FDS images out there instead of the mixture we have currently.

Big crutch is the cost for sealed games naturally, or even finding them in the first place. What I was wanting to know if anybody can compare what I've dumped to games that have been used and dumped with Loopy's device. Look at the differences and see if there's a way to "clean" used copies to look like new. Because honestly I'll never be able to afford new copies of every FDS game :)

If you're interested in the dumps shoot me a PM. Thanks!


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PostPosted: Sat Sep 05, 2015 8:43 am 
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I'm not sure what you mean. You are dumping games with FDSStick and you want others to compare if their dumps are the same as yours?


Anyway I played some more Yume Koujou and compared the save file after each cleared chapter.


Yume Koujou Doki Doki Panic SAV-DAT file observation ($CC91 in FDS file)

The first four bytes contains information on what chapters are beaten
for each character in order: Imajin, Lina, Mama, Papa.
Each bit in these bytes is a chapter where bit 0 is chapter 1 and bit 7
is chapter 8 (you can beat chapters out of order by warping I guess).
1 = beaten 0 = not yet beaten.

The last two bytes in the file seems to be some kind of checksum. If you
change it, the saved progress seems to be erased. That's why it doesn't
matter what they are when you purge them. They will always revert to
$5A $A5 by the game (I tried saving right after the game had purged it,
and it became: 00 00 00 00 5A A5).

I purged the SAV-DAT file to:
00 00 00 00 00 00

Beat chapter 1 with Imajin:
01 00 00 00 5A A5

Beat chapter 2 with Imajin:
02 00 00 00 5A A5

Beat chapter 3 with Imajin:
07 00 00 00 5A A5

Still no changes to the last to byte. To be continued...


Edit: Oops I realized it's only 7 chapters, not 8.


Last edited by Pokun on Wed Sep 16, 2015 2:40 pm, edited 1 time in total.

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PostPosted: Sat Sep 05, 2015 9:18 am 
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Yep I'm trying to see what the differences are between sealed dumps vs dumps that have been played. I have a dumped sealed copy of Doki Doki Panic with FDS, RAW, and BIN. Was curious to compare them to see if it's really necessary to purchase sealed games for dumps.


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PostPosted: Sat Sep 05, 2015 2:31 pm 
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Hubz wrote:
Yep I'm trying to see what the differences are between sealed dumps vs dumps that have been played. I have a dumped sealed copy of Doki Doki Panic with FDS, RAW, and BIN. Was curious to compare them to see if it's really necessary to purchase sealed games for dumps.


It depends on what you want. A sealed game is not necessary for a dump of Pro Wrestling because that game does not save anything to disk. If your dumping program compares the checksums on the disk and finds good checksums for every file on the disk, then you should be good. For the games that save, a dump of a sealed game that has never been played is ideal. If the dump comes out good, then you can have a pristine experience without any worries that you erased data that you should not have. Or if you find the cartridges that were in the Disk Writers, you could try those :)

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PostPosted: Sat Sep 05, 2015 4:04 pm 
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If you dump two or three disks and they have the same data, you can have pretty good confidence that it's alright. FDS had copy protection too, intending to prevent people from making copies of games with the FDS hardware, but it prevents overwriting the non save-game areas, so someone would have to mod their FDS or have some other kind of hardware failure to corrupt anything but the save area.


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PostPosted: Sun Sep 06, 2015 9:09 am 
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You may not need to dump multiple disks if one disk gives no checksum errors after a dump. Good dumping tools should alert you to checksum errors.

Now if you have checksum errors, then you need multiple disks. You also need to check the version byte to make sure that you are using the same version of a game. However, if you can get good checksums from every block by using multiple disks, then you should be able to "stitch" them together to make one good game dump.

Finally, as rainwarrior said, your dumping program must dump the whole surface of the disk, not to just the last file number as reported by the official File amount block. That will capture any hidden files used for copy protection purposes.

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PostPosted: Thu Sep 10, 2015 10:13 am 
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Having compared four dumps from sealed disk images from Hubz with the available TOSEC collection images, I find that the TOSEC dumps are solid in terms of playability. Disk Info Blocks have different or missing information from them, but that does not affect the playability of the image itself. There are repeating patterns of 6C BD found in his images not found in the TOSEC images, but I did not deem them to be important to game playability.

Metroid was a more interesting case. The save files are not named in the TOSEC images, but are in Hubz' dump. Side A is SAVEDATA (and should have an ID of 15) and Side B is MENSAVE. Note that Version 1.1 Side B has only MENSAVE, while Version 1.2's Side B has MENSAVE2 then MENSAVE. Hubz' has Version 1.2, so I am inferring the file name for 1.1. However, once a write to these files occurs, the filenames are turned into 02 02 02 02 02 02 02 02 the ID on side A's file turns to 14. This behavior occurs with an FDS RAM Adapter and an FDSStick and presumably every emulator out there.

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PostPosted: Sat Aug 05, 2017 1:55 pm 
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Sorry to bump an old thread, but I was wondering how much further this project progressed (if at all).

I'm also specifically curious about the Famicom Disk System game Konamic Tennis -- since I have a half-complete translation of the game I've been tinkering with -- and whether circulating images have any lingering save data that should be zeroed, restored, or otherwise neutralized. The image on which I've based my translation hack has a CRC32 of ac4ed201, if that's helpful.


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PostPosted: Sat Aug 05, 2017 7:17 pm 
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goldenband wrote:
Sorry to bump an old thread, but I was wondering how much further this project progressed (if at all).

I'm also specifically curious about the Famicom Disk System game Konamic Tennis -- since I have a half-complete translation of the game I've been tinkering with -- and whether circulating images have any lingering save data that should be zeroed, restored, or otherwise neutralized. The image on which I've based my translation hack has a CRC32 of ac4ed201, if that's helpful.


Nope, and admittedly I have been lazy when it comes to reviewing recently translated games like the Famicom Gran Prix games.

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PostPosted: Sun Aug 06, 2017 1:19 am 
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I think bumping this thread is a good thing though. The information here should be easily accessible somewhere, like the wiki. Not sure if it has a place on a development wiki though. I guess it can be seen as save file examples for FDS games.


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