[tryphon]

I'm working on some Genesis games and for the moment, I didn't bother about identifying precisely the original ROM.

Now that I try, I realize that several version of them exist.

For example, I work on Moving Adventure Psy-O-Blade and Rent-A-Hero, and I found those, all in Goodgens 3.0 :

Rent A Hero (J) [!]
Rent A Hero (J) [h1C]
Rent A Hero (J) [h2C]

Psy-O-Blade Moving Adventure (J) [!]
Psy-O-Blade Moving Adventure (J) [h1C]
Psy-O-Blade Moving Adventure (J) [o1]

The size are not the same : Psy-O-Blade Moving Adventure (J) [o1] is 1024 kB long whereas others are 640 Kb. I didn't try to analyze the extradata,but it's not zeros.

Could someone explain what the letters mean and which version is the more suitable as a base for a hack ?

[STARWIN]

quick google for letter definitions: http://en.wikipedia.org/wiki/GoodTools

it seems that you only have one real choice for each

[mziab]

When looking for clean roms, you should basically steer clear of most square bracket codes, with the sole exception of [!]:

[hXX] are hacked roms, in practice just a hacked header is enough to warrant this label.
[oX] are overdumps, which will work but as the name suggests contain redundant data.
[!] are verified dumps, which is a Good Thing™.

On a related note, the policy of including even known bad dumps in GoodTools is the exact reason why many people have switched to NoIntro sets, which contain only proper dumps.

[tryphon]

Thanks a lot

[obscurumlux01]

Please be sure to use the ! versions of the ROMs.  There should be some utilities that verify those ROMs for you.  I'm currently aware only of one command-line utility for non-SNES roms (uCON).

[snarfblam]

ROM Hasher can check ROMs for most systems against the No-Intro database.

[tryphon]

Marvellous. Downloaded, thanks

While I'm at it, must I compute all check values for an ISO (PS2 game) if I want to submit a translation, and if so, can I use ROM Hasher ?