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 Message Boards » » whats does 'variable' mean in 24x variable cd-rom Page [1]  
seedless
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?

can it be used for dvds?

10/21/2006 10:23:28 AM

MiniMe_877
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more than likely it means that the very outside track reads at 24x, the inner tracks read slower

10/21/2006 10:42:36 AM

seedless
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oh ok
thx

10/21/2006 11:29:27 AM

Bakunin
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yep, means it's a constant angular velocity (CAV) and not constant linear velocity (CLV) drive

pretty much all modern CD-ROM drives are CAV though... around 52x the inertia is enough to cause some cheap CDs to shatter, limiting CLV read speeds to much less than 52x since the disc can't accelerate the outer zone past that 52x data rate to maintain the data rate towards the inner zones

the real question is, why is data pretty much universally written to the inner (slowest) zone first? considering that most ISOs seem to be less than half the size of a full CD, it follows that most data-bound CD operations (installation from CD or writing a CD image to a CD) would be accelerated by a factor of 2 or more by having the sector addressing start in the outer zone

[Edited on October 21, 2006 at 12:13 PM. Reason : *]

10/21/2006 12:12:40 PM

El Nachó
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You didn't really just ask if a cd-rom drive could read DVDs.

Did you?

10/21/2006 3:55:07 PM

lafta
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you can store dvd's in a cd drive.

10/21/2006 4:19:08 PM

Noen
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^^^Dreamcast discs were arranged this way IIRC

HAHAha, can it read dvd's

10/21/2006 5:46:35 PM

seedless
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i was just asking because installed this program from a disc that said a DVD - ROM was REQUIRED and my disc reader says it is a variable 24x cd-rom module

http://www.viva-media.com/product_info.php?products_id=38&osCsid=d30e565973dddf016794eeac0866e20d

so asking will it read dvds, is that really a stupid question?

[Edited on October 21, 2006 at 6:35 PM. Reason : stf]

10/21/2006 6:34:28 PM

Aficionado
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yes

10/21/2006 6:54:01 PM

seedless
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oh, ok

well i don't know much about this stuff

i just wanted to clarify its use

could you please explain why it says dvd-rom required when i don't have one, or unless cd-rom and dvd-rom are interchangable at times, or whatever?

thanks in advance

10/21/2006 7:00:28 PM

gs7
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cd = compact disc
dvd = digital versatile disc (or digital video disc)

cd = 700mb
dvd = 4.7gb

even though the discs are physically the same size, what counts is the microscopic grooves in the discs that are read by tiny wavelengths of light (lasers). in this case, dvds have a larger capacity because they have much smaller grooves and require being read by a much smaller laser. cd-roms are made for just reading the larger grooves in cds. dvd-roms can read those larger grooves as well, it's called backwards compatibility.

sorry for the messy explanation.

10/21/2006 7:26:36 PM

Bakunin
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I think my point is pretty valid

Quote :
"the real question is, why is data pretty much universally written to the inner (slowest) zone first? considering that most ISOs seem to be less than half the size of a full CD, it follows that most data-bound CD operations (installation from CD or writing a CD image to a CD) would be accelerated by a factor of 2 or more by having the sector addressing start in the outer zone"

10/21/2006 9:48:45 PM

Redneck Bob
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The only thing I can think of they figured they might want to reduce the size of a CD at some point like those novelty CD's with the parabola's cut out.

10/21/2006 10:20:59 PM

HaLo
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also, its probably easier to scratch a CD on the outside rather than the inside.

10/22/2006 12:47:39 AM

pochacco20
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seedless, that software is on a CD and that's why it works in your CD-ROM drive. A lot of times those "requirements" are sloppy and they aren't necessarily required. A lot of games will give a list of minimum system requirements such as processor speed and main memory, but you can sometimes get away with something slower. Same with Windows, I've had XP run on systems way slower and older than what they "require" so I guess it's just a guideline. My guess is that the list of requirements for that chess game was just copied and pasted from a bunch of other requirements they made for a bunch of other games they made. Anyway, it's not important.

10/22/2006 10:43:00 AM

MiniMe_877
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^^^^ your point is valid, Sony got it right like Noen said, Dreamcast games were arranged with a large blank data file that was written to the CD first which took up most of the inner track area of the CD, and the game data was effectively written to outermost portion of the CD which sped up data access on Dreamcast

Its a shame that the concept wasnt applied to other CD burning applications, but is it really necessary now that most CD drives are so fast now? is 52X not fast enough? The inner tracks read at ~20x while the outer tracks approach 52x

[Edited on October 23, 2006 at 10:25 AM. Reason : .]

10/23/2006 10:25:03 AM

Kris
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can my cassette player play cd's?

10/23/2006 11:00:20 AM

JaegerNCSU
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Quote :
"^^^Dreamcast discs were arranged this way IIRC"


That's not necessarily specific to the DC. Most console development tools have a disc layout utility. Developers spend a lot of time designing the disc layout and arranging files on the disc to maximize throughput and reduce seek times. It's the last development step, usually, but it takes a bit of time and is more or less a black art in terms of finding the correct balance of where files need to (physically) be on the disc and with what alignment.

10/23/2006 11:09:09 AM

El Nachó
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I just remember when you were burning Dreamcast games you always had to burn a dummy file to the inside of the disc so the game data would be on the outside and the load times would be less.

10/23/2006 11:14:30 AM

abbradsh
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can my 8 track play mp3s?

10/23/2006 11:35:15 AM

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