Thanks it290, but please keep in mind that if there is a video-game preservation website with official documents that explain the differences better (e.g., with translations from Konami game manuals and the like), they automatically beat (up) my observations. This is what I noticed from simply playing the games but never really researching the details, simply put.
Anyway:
I believe that Konami used a board (GGX?) for a number of early '90s arcade titles, and used a three-letter code for the different revisions, e.g. "JAB" or "UAB". The first letter should represent the region: "J=Japan", "U=US", "E=Europe", "A=Asia". The second letter might simply be "A=Arcade", as I cannot figure out what it stands for. The third letter should represent the game revision: "A=first revision", "B=second revision", "C=third revision". So, "JAB" seems to be short for "Japan region, Arcade Version, Second revision".
Let's then discuss two specific game examples.
I 1-CC'ed the AAA version of Konami's
X-Men, which is the A(sian)A(rcade)A(first revision) of the game, but not the other versions. For
Violent Storm, I 1-CC'ed the JAC version, which is the J(apan)A(rcade)C(third revision). I believe that there should be quite a few other revisions for
X-Men, and other Konami games (e.g.,
Bucky O'Hare,
Metamorphic Force) have several revisions also following the same naming system. The general idea is that the third letter tells you which revision is the newer and possibly easier revision of the game, and the first letter tells you which region-specific version you are playing (with U=US, usually the hardest; A=Asia and E=Europe, usually easier; J=Japan, usually the easiest).
OK, let's now focus on
Violent Storm.
The JAC (i.e. third) revision of
Violent Storm is easier than the JAB revision (i.e. the second revision), and the other regional revisions: it gives more energy drops, enemies are a bit less aggressive and fast (and have less HP's). In general, it makes life a bit easier for players. Like all the other revisions, it has a loop that players can access once they clear the first loop (called "Normal round" in the game). The loop is called "Violent round" in the game. Regardless of the revisions you play, the dipswitch settings have two options:
1. The default option on the JAC version is "One round only". If you clear the Normal round, you continue onto the Violent round and go through all seven stages again. In this case, each stage has *way* more enemies and all enemies are more aggressive, fast and sturdy. This means that enemies in the Violent round are as though as they are in the JAB version, and in several spots there are way more enemies to fight (see previous post on this matter);
2. The other option is "endless", i.e. endless loops. If you clear the Normal round, you continue onto the Violent round and go through all seven stages again. In this case, only ST 1 and ST 2 have a few more enemies, but all enemies are more aggressive, fast and sturdy. Furthermore, if you clear the Violent round, you start again (whence the "endless" label). Basically, the Violent round/loop in the "endless" mode is as difficult as the JAB revision of the game.
The differences amongst the different regions can be summarised in this manner (Default dipswitch settings, and I may have forgotten some details):
1. Only the Japan versions (JAB, JAC) have extends (500k, then 1,5 M, 2,5 M, 3,5 M...etc.). The other versions give players one spare life and that's it;
2. The US versions (UAB, UAC) should have the "blood" option from the beginning. The other versions will only add blood in the Violent round;
3. All versions have the "1 loop only/endless" dipswitch setting. The difficulty seems to increase in a parallel manner, so the UAB version of the game (i.e. the hardest version) has a Violent round that has tons of enemies with tons of HP's and going at crazy speeds, with next to no energy drops during the levels.
Basically, if you play the JAC version, you are playing the easiest version/revision of the game. If you can access the loop/Violent round and the game is set on "endless", you can potentially play a harder version of the game that is roughly equivalent to the JAB version, and if you are really good, you can do it for hours on end,
Gradius-style.
Case in point, yesterday I tried the "endless" option on the JAC version and reached the fourth stage of the second loop (i.e. I cleared 7+7+4 stages). I then had to take a breather and decided to quit it, since I am now an old guy and 1 h 30' of continuous gaming almost killed me.
Once more, if someone like Trap15 drops by and links us to a website with official documentation on how Konami arcade games' revisions work, the official documentation wins (of course)...
...But if I got it right by simply taking notice of the basic details, then I can consider myself a satisfied man
Chomsky, Buckminster Fuller, Yunus and Glass would have played Battle Garegga, for sure.