Discerning cartridge file sizes.

[Chris]

Previously I posted in regard to some GBA dumps of mine that were not working and with the help of Matthias learned it was due to the Retrode erroneously under dumping (failing to copy the entire game ROM) the game because it's automatic size detection came back with the wrong size.

This matter was solved by simply manually setting the Retrode to the correct size in it's configuration settings.

Matthias in this instance told me the correct sizes to set for, however, as this can happen again with other games in the future I would like to know how I can decern for myself what the correct file size is. Unfortunately ascertaining this information has proven to be somewhat more complex than a mere Google search as just about any search containing any word remotely related to ROMs only turns up sites hosting ROMs for download.

I do know that these ROMs do have information regarding their file size listed in their header, and that any partially successful dump should contain the header information so if anyone knows of any utilies for reading the header information or listing of correct file sizes posted out there I would find such information quite useful.

I just don't want to have to bother anyone with such questions again in the future. This way I can be more self sufficient in my backup efforts.

In addition to using this to correct under dumping I shall also be using it to check my files for signs of over dumping.

[Matthias_H]

The problem is that unlike most other systems, GBA and N64 ROMs do NOT have the size in their headers, so the Retrode has to make a guess from the looks of the data that is there. Overdumping will not cause problems in most cases, since all the data required is in the right place. You may get checksum complaints (if the data doesn't "add up" to the right known value) but the game should still run just fine.

Cheers,
Matthias

[MasterOfPuppets]

You can check sizes here. GBA games range from 4MB to 32MB.

http://datomatic.no-intro.org/

[Chris]

My concern about over dumping has nothing to do with functionality. I am aware that an overdumped game should work, but It will also take up additional space which can be wasteful on some smaller storage media. I already zip most of my files to conserve space because the phone I do much of my emulation on has a fairly limited storage capacity and I have hundreds of games to load up on it for dozens of platforms.

[Matthias_H]

If you zip the ROMs anyway, overdumping will add no more than a few bytes of storage (no new data, nothing to compress).