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When you don't have the right rom: Info-Guide to checksumming

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kdecks
Posted: 31 Oct, 2017 03:16
Last Edit: 31 Oct, 2017 03:17
Written by transposed from Discord


WHY IS MY GAME LOADING UP A "{}" OR A "NULL" OR A DIFFERENT GAME'S ACHIEVEMENTS WHEN I START IT UP?

1a. How games are matched to their sets

Retroachievements.org uses a specialized method of matching the game you have loaded on your computer to a set of achievements for you to unlock online. Since it would be pricey to have to upload your whole ROM file to our servers to match the game you are playing, and the filenames given to every ROM are not always the same, we use a technique called md5 checksuming to detect which game you are playing, and load up the proper set in the emulator.

1b. What is checksuming?

Checksuming is a nerdy math equation that will always give the same number (known as the RA-branded md5 hash [specific to game ROMs]) back for the same file, and will always give a unique number back if the file has been changed or is slightly different. Checksuming is a pretty amazing (but not fool-proof) anti-piracy measure used in all gaming consoles. Just as this number lets a manufacturer of our favorite old video games know if something about a game cartridge or disc just isn't quite right (its been copied or hacked!), the same thing is done over here at Retroachievements to prevent games from being loaded in that could contain some...not so nice extra features. :cheese:

1c. So why does a different or oddly named game load? Whats checksuming got to do with it?

If your game ROM has been modified or poorly copied from its original game cartridge, this number will be different. Your special unique number for your ROM must match the one on the RA servers. If it doesn't, some very interesting things may happen (which is why you are here!)
1d. Possible md5 checksum mis-matching scenarios:

Your rom loads as the "NULL" game, or the "{}" game, or the "UNKNOWN" game, or has a blank title, with no achievements.
Your rom loads as a completely different game, that its unique number just happens to match something else.
You receive a pop-up when your game loads. Asking you to name your game. (SEE 4a. My game is asking me to give it a name! on this solution immediately, before you just click OK!)

2a. How do I fix this? IS RA BROKEN?! WHAT DID I DO?

Calm down, the website is not broken, your ROM is. Utilize your super-secret powers of finding yourself a ROM file that loads the proper set or follow the instructions that came with your ROM dumping device (properly, this time!). We do not provide download links to ROM files for many legal reasons. Retroachievements.org's emulators are free for you to use. Video Games are not free. We will not condone discussion or publicly support in any fashion the distribution of pirated content or share download links to ROMs. This is a bannable offense for you, as well! See the website's rules document.

2b. BUT...IT LOOKS LIKE THE ORIGINAL GAME!?

Well, just as you may have screwed up on a dump or two, so may have someone else...
3a. I have followed all the advice above and the wrong set is still loading!

...1. Be sure that your ROM matches the region displayed for the set on the website. Here's a quick key reference to how to verify your ROM's region is the correct one.

a. Multilingual roms that contain a language select are most often not supported, and are usually modified from the original. If your game never contained a language selection screen, its been modified, and won't work.
b. NTSC roms are most often US or Japanese region ROMs (US, USA, U, J, JAP)
c. PAL roms are most often European ROMs (E, EU, RU, FR, WS, PL, etc.)
d. Verify the ROM you are loading matches the same region code as the set on Retroachievements.

EXAMPLE: Ristar (E) means the PAL, European ROM. The set has been designed for this region, only.

...2. Be sure the ROM has not had its header removed, misplaced, padded out, or corrupted.

a. This problem often occurs with third party hardware dumpers. Be sure your dumping device is configured to dump the header correctly.
b. Hacking tools may have been used to strip the file of its header. In some cases, this may be done to remove annoying intro screens, or skip the boot logo.
c. In some cases, a set will specify an intro-less ROM (especially in the case of GBA games) If the set specifies an intro-less ROM, you will have to locate the appropriate intro-less ROM file yourself. Otherwise, avoid grabbing these.

EXAMPLE: Pokemon Pinball (Ruby & Sapphire) (U) (Intro-less) Requires you to play the NTSC USA-branded Intro-less version of the game.(edited)
...3. Your rom isn't the correct revision of the game.

a. Some games, like Legend of Zelda - Ocarina of Time, have multiple release revisions. In LoZ - OoT's case, the gold cartridge is version 1.0 with the holographic label, 1.1 with the standard label, and the grey cart was 1.2, with an additional patch released 1.3. Due to the memory inside of your game cartridge being vastly different across revisions, you will have to be sure the version specified on the website matches that of your ROM.
b. Your ROM is a beta or prototype version of the game. In a few cases with games that never made the final cut, this may be admissible. Starfox 2 Beta w/ fix patch to make the game playable is a perfect example of a game that ended up this way. In almost every other case, no, your prototype ROM won't work.
c. You are playing a hack that has been incorrectly patched. YES - We offer some fun ROM hack sets, but you must be sure the IPS patch you are applying matches both the specified version of the game suitable for the patch itself, and the version of the IPS patch specified on RA in order to load up the proper set for these specialty custom titles.

...............EXAMPLES: Super Mario RPG - Armageddon v7 (easy mode) - Requires that you have the IPS patch for release version 7 of the hack, of which the IPS file explicity says "(easy mode)"
.............................Sonic 3 (U) - Requires you to play the real NTSC USA Sonic 3 and not the fake alpha "prototype" released some mid 2007 on the internet.

4a. My game is asking me to give it a name!

You just loaded up something new! Even if its the same game, its hash hasn't been found anywhere in Retroachievements' big swimming pool of ROMs.
Stop, think, name your game appropriately. Use correct grammar, and spelling, don't be a troll. Its super easy. Your extra effort, and descriptiveness in game revision number and development status, makes the moderator team's jobs much, much easier. Be descriptive, and concise.

((GOOD NAMING CONVENTIONS:))
Super Nintendo Burn-In Test Cart (NTSC-U) (Rev5)
Starfox 64 (NTSC-U) (Blockbuster Competition Kiosk Edition)

((BAD NAMING CONVENTIONS:))
dumb game2
fuk this ghem
y?
h4x0r to the m4x0r smw
I hacked this you play it you much leik

If your game happens to be very similar to the point it will work to be merged into a set along with the same game of the same title, it'll be looked over by the devs and mods. You'll still need to find the right ROM, but thanks for letting us know! APPROPRIATELY!

5a. I have some other issue not stated above with getting the right set to load.

If all else fails, make sure the site itself isn't experiencing some sort of issue. Check #community-news here for site status.
If you need help beyond this point sigh ask someone with a mod or an admin role.

meleu
Posted: 31 Oct, 2017 12:15
Can I use this thread to recommend my hascheevos tool? I hope yes :D

Here it go:

Linux users (or Windows users using Cygwin or MSYS2) can use the hascheevos tool to check if a ROM is OK for cheevos. More info here:
https://github.com/meleu/hascheevos

MaxBeta
Posted: 09 Jan, 2018 20:41
Last Edit: 10 Jan, 2018 09:10
Hello,

I've been trying to get MSU-1 Super Metroid to work with Retroachievements but have had no luck.
The clean rom works fine but no longer works after patched with MSU-1 hack.
I can assure you other games like DKC1, DKC2 and Actraiser work just fine with Retroachievements even after they are MSU-1 patched but for some reason Super Metroid won't.

I've named the rom Super Metroid (NTSC-U) and it still won't work.
Any help is appreciated.

kdecks
Posted: 21 Jan, 2018 01:38
The name is unimportant. What's important is that the checksum matches our supported checksum.

21f3e98df4780ee1c667b84e57d88675 - Super Metroid (Japan, USA) (En,Ja) [[this is known under other names as well]]

Depending on this hack it can become supported but we need to know what it is and what it's doing to the game. can you describe it and find out the hacked rom checksum?




bigclown187
Posted: 24 Jun, 2018 03:27
I fixed all of my incorrect roms by going to the No-Intro site and getting the .dat file for each system. I then ran the folders through RomCenter to determine which were not in their db. No-Intro isn't the sole authority on rom verification as there are other groups as well. I've had a couple roms (N64 I believe) that RetroArch claimed were good but No-Intro claimed were overdumped and vice versa.

Btw, RomCenter gave me errors for a couple of systems loading their .dat file from No-Intro so I was forced to create my own C# app to load their .dat and verify against my rom folder.

bigclown187
Posted: 24 Jun, 2018 03:29
Last Edit: 24 Jun, 2018 03:29
I forgot to mention that RomCenter will correct the filenames of your roms based on the info in the .dat file that you load in case you want to do that. Just keep in mind that you will have to go in and rename your save files to reflect the change.

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