What is a (Rev B) ROM?

[Airikita]

I am just curious as I have found a ROM on a site with (Rev B) in the file name... does anyone understand what this implies?

[Pennywise]

Rev B is like version 1.1 of a ROM. Back in the day when a publisher did another cartridge run and the ROM was changed/updated, they'd call it Rev B. Something like that.

[taikyoku]

per above. there are differing standards per rom info or dumping group, per console, and even per website. some examples:

-you may see "REV 00" and the like for mega drive games. there's also stuff like sonic 1's "REV XB", referring to the sonic mega collection which had been developed for xbox apparently.
-you may see "PRG0" for nes games. this raises the question of what exactly smb's "PRG1" is, as there's only one JU rom in most newer dumps.
-you will generally see "V1.0" for snes games, and for certain dumps of game boy games. no-intro uses the "Rev B" system for game boy, though. and i think it's actually "<no label>" for the earliest version, then "Rev A", then "Rev B", which would make sense.

with the game boy bit in mind, these all mean about the same thing: "REV 01" = "PRG1" = "V1.1" = "Rev A". i assume some of the differing standards come from something in the hardware.

by the way, if you see any snes games labeled "(NP)", those are related. these roms were released through the japanese "nintendo power" service (completely unrelated to the north american magazine of the same name) and generally have some bugfixes; you will often find a "V1.1" or even ".2" attached to them, unless the game is NP only.

[FallenAngel2387]

Generally you'll want the latest, but there are instances when one might prefer an earlier revision.

A couple Genesis examples:
The Revenge of Shinobi gets more and more copyright infringing the further back it goes. For example, in the 00 revision one boss battle is effectively Spider-Man(with the correct color scheme and everything) that transforms into Batman.

Michael Jackson's Moonwalker is another. Apparently MJ didn't have the rights to Thriller, which starts up as you dance with the zombies in stage 3, but was taken out in the later, more common revision.

A Game Boy example would be Link's Awakening, but I'm not sure if this pertains to the non-DX version. Anyway, the latest is the only one without a glitch involving the Select button and the map, which allows you to warp to the next screen, whether you can get there on your own at that point, or not.

Usually they're bug fixes, or other little cosmetic updates, but sometimes the earlier revisions seem cooler.

[KingMike]

In Link's Awakening, it is only 1.1 that has the warp glitch fixed. 1.0 and 1.2 contain the bug (I can confirm it works on Player's Choice, which are definitely 1.2. I know it worked on my first copy, which had to have been 1.0 as I had the game a few weeks after it was out.)
It's said Nintendo actually undid all the 1.0->1.1 fixes when they made 1.2, so supposedly the level 4 sequence break that can cause you to run out of available keys was put back in.