Quick CHD Mame Version question

[DeLuSioNal29]

Hi all,

Quick question, do the CHD versions ever change like MAME romsets do?  ie - will .128 CHDs work with .119 MAME (using .119 roms).

Thanks in advance.

~ DeLuSioNaL

[Tafoid]

Yes.  Hardly ever happens, however, as most of the time the CHD is complete (since it's essentially an image of a whole drive or CD - it's an all or nothing situation).  The only one in recent memory that changed was in case of CARNEVIL (in 0.128u6), that recently got a new confirmed dump and the previous CHD that *WAS* named CARNEVIL got moved to a clone set, CARNEVI1.  Since the actual rom chips are the same in the two CHD's - you should be able to simply rename the pre-0.128u6 CARNEVIL.CHD to CARNEVI1.CHD and run that as before.

[u_rebelscum]

I'll add just a little to Tafoid's post.

Sometimes they change, for the same reasons as ROM sets change, but less often for a few reasons:

• there are less chd files than ROM sets.  So if 99.9% of both ROM sets and CHDs stayed the same, that's ~7 ROM sets (out of ~7500) that change, and less than one CHD (out of 306)
• as Tafoid said, chd has only one "file" inside, while ROM sets (zip file) have multiple ROM files inside (average 15 ROMs per ROM set) and if any one of the files change, it "breaks" the ROM set from working.  Since these are the shuff that really change, this is a better thing to see what changes.  If 99.99% of the the ROM files and CHD files stayed the same, that's ~11 ROMs (or about the same number ROM sets) that change, and 1/10 of the above "less than one" CHDs.
• some of the CHD changes were able to be fixed with mame chdman tool
• still, it seems like chds are an order of magnitude stabler than ROMs, OTTOMH

So most likely the CHD will work.  But 0.119 was about a year ago... clrmamepro (or chdman -verify) can verify if the chd will work.