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Posted by Citizen Bob on 12/14/06 17:09
On 14 Dec 2006 15:51:12 GMT, Bert Hyman <bert@iphouse.com> wrote:
>spam@uce.gov (Citizen Bob) wrote in
>news:458020bc.34852781@news-server.houston.rr.com:
>
>> ISO is an archive format similar to ZIP and RAR.
>
>No. Calling a file an "ISO file" is a shorthand way of saying that
>it's a byte-for-byte image of a CD or DVD in the format specified by
>ISO, The International Organization for Standardization.
>
>http://www.iso.org/
http://en.wikipedia.org/wiki/Iso_image
+++
An ISO image (.iso - InSide Out) is an informal term for a disk image
of an ISO 9660 file system. More loosely, it refers to any optical
disk image, even a UDF image.
As is typical for disk images, in addition to the data files that are
contained in the ISO image, it also contains all the filesystem
metadata (boot code, structures, and attributes). All of this
information is contained in a single file. These properties make it an
attractive alternative to physical media for the distribution of
software that requires this additional information as it is simple to
retrieve over the Internet.
Some of the common uses include the distribution of operating systems,
such as Linux or BSD systems, and LiveCDs.
Most CD/DVD authoring utilities can deal with ISO images: Producing
them either by copying the data from existing media or generating new
ones from existing files, or using them to create a copy on physical
media.
Most operating systems (including Mac OS, Mac OS X, BSD, Linux, and
Windows with Microsoft Virtual CD-ROM panel) allow these images to be
mounted as if they were physical disks, making them somewhat useful as
a universal archive format.
Console emulators, such as ePSXe, and many other emulators that read
from CD/DVD, are able to run ISO/BIN (and other similar formats)
instead of running directly from the CD drive. Better performance is
achieved by running an ISO since there is no waiting for the drive to
be ready and the hard drive I/O speed is many times faster than the
CD/DVD drive.
A copy of CD contents, stored as an .iso file, is made this way: the
ripper searches for the sectors of the CD that have been used, say
251,000 for instance (there are 330,000 sectors on a 74 min CD and
360,000 sectors on an 80 min CD). Each sector is copied to the .ISO
file, one by one. For CDs each sector is 2048 bytes, the .ISO file
should then be of size 251,000 x 2048 = 514,408,000 bytes(s).
+++
--
Government's view of the economy could be summed up in a
few short phrases: If it moves, tax it. If it keeps moving,
regulate it. And if it stops moving, subsidize it.
--Ronald Reagan
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