Please explain the MAME missing rom system

[Blanka]

When running Mame I found out the with each new versions, more ROMs are missing from romsets. I have a Taito Legends PC CD and the ROMs on it play nice in Mame 0.103, but don't play in Mame 0.124?

I don't get this.
I would think that if someone rips an original PCB, he reads out every ROM on the PCB and puts it in a romset. Why are there added new roms to many very old sets than all the time with newer MAME versions. Did they skip a few Roms in the first place? Can someone explain this in Plain Belgian English (or Blonde English)?

[Robbbert]

They skipped a few roms in the first place; OR they were using the wrong rom with that game, and now they've "fixed" it.

Just like all those CPS-1 games; they finally decided to add the 5 PAL devices to each game, even though they aren't hooked up yet. You still need to supply the extra roms though.

[waveryder]

Most of the time roms are incorrectly dumped or are "brute forced" due to their encryption. These issues tend not to come to light until the mamedevs "document" the boards more precisely. As they do roms are redumped sometimes even returning to original dumps! Remember there tends to be very little documentation freely avaliable about arcade systems to prevent piracy (well back in the day). So the development of an arcade system never really stops.

Quote from board dumping legend The Guru:

"Many EPROMs on arcade boards are in sockets and it's fairly simple to remove them, read, then save the binary info that they contain. However, in some cases, it's not quite so simple with surface mounted ROMs being more common on newer arcade boards and strange types that are unusual or unknown. Sometimes we make an *educated* guess when this occurs and mostly we get it right, but sometimes a misjudgement on the dumpers' behalf results in a bad or incomplete dump, which must then be re-dumped at some point in the future (and hopefully the PCB is still available!)"

[Blanka]

Can you have a front-end run different versions of Mame then, and decide per game which mame to run? I cannot call Digital Eclipse and tell them palce16v8q-d77-13.bin is missing in their CD, please e-mail it! They will say just eat all our copy-protection crap and install it the normal way.

[waveryder]

Can you have a front-end run different versions of Mame then, and decide per game which mame to run? I cannot call Digital Eclipse and tell them palce16v8q-d77-13.bin is missing in their CD, please e-mail it! They will say just eat all our copy-protection crap and install it the normal way.

Some can some cant depends on the frontend. Why not just audit your roms and download whats missing for the latest mame. Or am I missing something ovious here?

[Blanka]

Why not just audit your roms and download whats missing for the latest mame.

That sounds easier than it is. I only ran into old rom sets wandering the net. And I'm not going to try the big torrents. Why do those basterds only upload 20Gb collections in huge ISO files. Just share some small collection with classics too, or keep individual items selectable for download (not iso-ing it to one big file).

[u_rebelscum]

... Can someone explain this in Plain Belgian English (or Blonde English)?

Pretty much answered already, but a little more info at mameDev FAQs

... the big torrents. Why do those basterds only upload 20Gb collections in huge ISO files. Just share some small collection with classics too, or keep individual items selectable for download (not iso-ing it to one big file).

A little OT, and a generalization, and boarding on taboo, too, but anyway...  The are those who like things bundled for them and those that don't (very general statement, and actually people are some of both, more one way at some things, more the other at others).  Examples: those who compile their own mame, vs those who don't; point 'n click cameras vs DSLRs; brand name computers vs BYO computers; windows vs linux.  I find that people who torrent usually like the files bundled.  So the people who share usually shared their stuff bundled, which atracks others who like bundles, and so on with positive feedback toward bundled stuff.  Meh.    (FWIW, IMO some stuff should be bundled, but it's too easy and too common to "over bundle".)