Questions about Bios/chd's etc.

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welby1
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Questions about Bios/chd's etc.

Post by welby1 »

Just curious, but is there a way to determine what games require a specific bios file? Some of them are pretty obvious, but not all.

What purpose do the chd files have, and how do you know if one is needed?
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Post by LN2 »

if you do an audit on the rom set, it will show you what rom files are missing. Normally you can see if a bios is needed from the missing list.

chd files are a compressed hard drive image file format....which more modern games in mame use.

the arcade games for these have actual hard drives etc. with the data on them.

I can't wait til mame has opengl use module to support the 3dfx arcade games
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Re: Questions about Bios/chd's etc.

Post by Weehawk »

welby1 wrote:Just curious, but is there a way to determine what games require a specific bios file? Some of them are pretty obvious, but not all.

What purpose do the chd files have, and how do you know if one is needed?
List of BIOS files:

http://www.mameworld.net/maws/srch.php?cat=2

Click on the file name to see what games require it.
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Post by mahlemiut »

LN2 wrote:chd files are a compressed hard drive image file format....which more modern games in mame use.
Not quite. CHD = Compressed Hunk of Data. It represents large storage media, typically hard disks or CD-ROMs
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Post by welby1 »

Didn't even think about the audit, and the list will help greatly.
Pretty much what I thought about the chd's.
Thanks.
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Post by LN2 »

[quote="mahlemiutNot quite. CHD = Compressed Hunk of Data. It represents large storage media, typically hard disks or CD-ROMs[/quote]

yeah, after the fact I realized many have it on CDs.

how far is mame from supporting laser disc games? sure, we have daphne, but it would be cool to have the laser disc image and mame play the game from those.
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Post by mahlemiut »

Don't hold your breath. :)

I'm sure Haze knows more technical details on why laser discs aren't dumped for MAME. All I remember is something about video codecs or something.
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Post by LN2 »

yeah, I can see licensing issues there perhaps.

it sounds more like where they want mame to be totally it's own thing...

in other words, if they could compile the codec within mame for the support, the developers would do it...but since it would require installing of someone else's software and reference the lib etc. they want no part of it.

oh well...not much you can do there.
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Post by mahlemiut »

It's more that the license needs to be compatible with the MAME license, as well as being available free to use. And also, a proper dump of the laser disc would be interesting too, as it's not digital.
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Post by LN2 »

good point....I wonder how large a "proper" laser disc dump would be.

it seems a truly accurate one would require a TV-card or equivalent to play the raw signal data...or was a codec actually used for those games?!?

I just remember those laser discs were huge...but perhaps no more data than a CD-ROM has nowadays?!?
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Post by The TJT »

Nah, more than a CD-ROM. They sell it in DVD at digitalleisure. Merely my Dragon's Lair Daphne converted video+sound takes 957MB hard disk space.

I don't get the difference between analog and digital here. Analog=movie, digital=computer...right? In order to play it with a computer it HAS to be converted to digital format, unless you have a movie disk and emulate movie playing hardware too. Did I get it right?
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Post by mahlemiut »

Anything stored on a CD or DVD is digital. Laser discs are analogue.
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Post by LN2 »

another way to perhaps say it is digital is data that just consists of zeroes and ones...

each site location on digital media is either 0/1 in value. or off/on...magnetized, not magnetized, etched, not etched, etc.

On analog media, you don't have 0/1s...but a stored degree of magnetism(in the case of VHS tapes, cassettes etc.
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