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[fleggett]

This is (probably) going to be a painfully newbish question, but I've always wondered something.  If one is using the internal database inside the actual MAME executable when creating a profile, are external DAT files needed for anything?  If so, when and where?  I'm trying to get back into the MAME scene after an extended absence and am having to relearn a lot of details (many of which I never fully grasped to begin with).  Thanks in advance!

[Roman]

for mame, mess, pinmame you dont need a dat since cmpro takes the info from the binary. but of course there are thousands of other systems out there where no emu exists and their software collections are listed as datfiles. look at the dats of tosec, no-intro and so on. or all the artwork related stuff (screenshots,flyers,etc) provided by progetto mame. actually there are even dats out there which have nothing to do with any emu or system. just hashes of files.

[fleggett]

Well, I asked because, whenever I do a block download from usenet, I'm left with a bunch of dat files of all filenames and sizes that I have absolutely no idea what to do with.  And since cmp uses the mame executable directly, I just didn't see any point in keeping them around (for roms, that is).  I can see where they'd be useful for anything not contained within mame itself, though.

Speaking of progetto, I ran into a rather interesting problem that doesn't look to be documented anywhere.  It seems mame has a filesize limit for "master zips" (like flyers.zip, cabinets.zip, icons.zip, etc.).  After grabbing the progetto archives, my flyers directory is now over 5 gigs (4,004 files).  I tried zip'ing them into just one flyers.zip, but was confounded when mame wasn't showing any of the flyer images that I knew for sure I had.  I tried various zip programs and compression options before I finally figured out that the sheer size of flyers.zip was too much for mame to handle.  I verified this by just zipping up a few flyer pngs and invoking mame and there they were.

Has anyone else run into a similar problem?  This is with 144.4.  I haven't yet tried it with 144.6.

[Roman]

The dats you're talking about are most likely fixdats. If someone misses files from a collection he/she usually posts fixdats to the usenet. These fixfiles (can be automatically created by cmpro) only hold the missing files. So someone else picks up this dat, loads it and rebuilds from his (most likely complete) collection the missing ones for the other user.

Regarding zip: Well, standard zip is limited to 4GB. Everything above is not a standard zipfile and is not processed by MAME which uses the zlib library to process zips. You need to store such collections in a not compressed way.

[fleggett]

They are, indeed, fixdats.  Is there anything I can do with them at this end?  Don't they just indicate which roms are missing with their associated CRCs and such?

Regarding zlib, is there any movement to use an updated library?  Maybe even one that supports 7z?  With the sheer availability of files available nowadays (particularly flyers), it would seem a prudent move.

[Roman]

you dont need the fixdats as long as you dont want to help out others with files which they are searching.

I dont think that mame will switch to anything else but zlib in the near future. terabyte prices are low and mamedevs dont care about rom collection sizes, so zlib is enough.

[fleggett]

Oh, I'm more than willing to assist others in completing their collection, but I've gotta understand the basics first.

That's too bad about zlib.  The version the devs are using is obviously outdated.  And it's anyone's guess at this point when HD prices will return to pre-flood levels.  Besides, by sticking to an obsolete library, they're regressing an advertised feature, which is generally a no-no without making users aware of the limitations of that feature.

Thanks for the help.  I'm sure I'll have yet more newbish questions soon.

[Roman]

it's no outdated. for archives bigger 4gb every zip tool manufacturer cooks his own soup and actually often charges for it. again, there is no real need for supporting such zips.