Mame rom version question

[eds1275]

I am trying to wrap my head around this rom version thing. Not that I need to understand at all - my setup works fine. I just like to know things.

Isn't a rom just a memory "dump" from a real piece of hardware? I am thinking that there's a good dump and a bad one, where the bad one didn't execute correctly. Obviously I'm missing something here. Besides CHD's, what's the deal with the different versions?

[BadMouth]

If you're talking about Parents/Clones......

They are variations that can be found on the actual arcade boards.
If you bought two MK boards off ebay.  One might turn out to be software revision v2.0, another might turn out to be revision 5.0

Problems were fixed or changes were made (in successive revisions) to the original boards to fix glitches, make the game work better, etc.

sometimes they are for different regions, i.e. North America, Japan, EUR, all the way down to individual countries that they may have had different versions for.
(the Japanese version of Vendetta has bad guys that prance around, then hump you.  It just wouldn't work in the NA market)
(In Europe, Teenage Mutant Ninja Turtles were called Teenage Mutant Hero Turtles, so a different version was needed)

Other times, they are bootlegs or hacks.  But they were bootlegs or hacks that were installed on real arcade boards, not made for MAME.

MAME is about preservation, so all versions found are preserved.


If you're talking about roms needing updated or rolled back to work with a particular version of MAME.....

I'm not as sure about that one, maybe someone more knowledgeable can chime in.
Sometimes not all chips on the board were dumped originally or there are other daughter boards or sound boards that weren't emulated in previous versions. 
(i.e. the game used sound samples in the last version of MAME, but now the sound board is emulated)
A lot of times, they just rename stuff or change how it's organized.

[newmanfamilyvlogs]

A lot of times, they just rename stuff or change how it's organized.

This.


Just cherry picking through a few "Whatsnew.txt" from various versions and taking them out of context:

 

409  Major toaplan2.c updates  [Alex Jackson]
  410   * Some sets reparented and renamed as well as a cleanup of source
  411      comments: grindstm (parent), vfive (clone) kingdmgp (parent),
  412      shippumd (clone) The set formerly known as "sstrikera" is now
  413      "sstriker" and is now the parent of mahoudai (clone). Reverted
  414      batrid to batrider and bkraid to bbakraid.

1361   * Identified and documented willowje as an early and genuine USA
 1362      release, added a note and renamed willowje -> willowo

- ncombata: fully redumped, renamed set to ncombath

wh2j: partially redumped, renamed to wh2jh, is verified AES version

- wh1ha: renamed from wh1h to wh1ha

- Renamed citalian -> cpokerpkg (green board, can be seen in rom too)
 - Renamed citaliana -> citalcup

NeoGeo update [Johnboy]
 - maglordh - Renamed p1 to correct chip label (MichaelNet)
 - Renamed maglordh to maglord (MVS) and maglord to maglordh (AES)
 - whp - Renamed several roms to correct chip label (MichaelNet)
 - kof2001 - Renamed p's to correct chip label; added note (MichaelNet)