![]() Mode 2 CD-ROMs do not specify a format for those 2336 bytes, but the CD-ROM XA extension defines two "forms" for mode 2 CD-ROMs: form 1, for example, fills the 2336 bytes as follows: 8 bytes for the sub-header, 2048 data bytes, 4 bytes for CRC and 276 bytes for ECC. Mode 1 CD-ROMs (those definitively supported by VirtualBox) follow this 16-byte header with 2048 bytes of data, 4 CRC bytes, 8 zero bytes, and finally 276 bytes for ECC. CD-ROMs use these 2352 bytes as follows: bytes 0 to 11 store a sync pattern 00 ff ff ff ff ff ff ff ff ff ff 00, bytes 12 to 15 contain an address (minutes, seconds, frame), byte 16 contains the CD-ROM "mode" (only modes 1 and 2 were defined by standards, I believe) and the remaining 2336 bytes are mode-specific. It's not s special purpose CD format, it's a standard CD-ROM format.ĪFAIK, all CDs use 2352-byte sectors, see e.g. There's music CDs of course (CD-A), Photo-CD, VideoCD etc. Was this a special purpose CD format? ISTR that these strange CD formats all had special purposes that died out. That's what ISO refers to: the ISO-9660 standard for data CDs (and its various modern tweaks for long filenames and deeply nested folders). in fact it expects ISO data in its ISO files. T wrote:As far as I can tell, VirtualBox expects the 2048-byte sector data in its CD-ROM ISO files. Is there a way to image my media so I can use virtual media files in VirtualBox, rather than using the physical CD-ROMs, which are starting to get a bit flakey, every time? And is there some place which documents the difference between DMG, CUE, RAW and VBoxIsoMaker as far as VirtualBox is concerned?ĭr. However, VirtualBox seems to support DMG, CUE, RAW and VBoxIsoMaker files for the virtual optical media - but I can't find any documentation explaining what these different formats are supposed to be. I'm able to archive the raw 2352-byte sector data, however it's not possible to meaningfully extract 2048-byte sector data.Īs far as I can tell, VirtualBox expects the 2048-byte sector data in its CD-ROM ISO files. To make matters more complicated, some sectors on these CD-ROMs are Mode 2 Form 2 sectors. On trying to archive some really old (about 20 years) CD-ROMs, I've come across some XA Mode 2 CD-ROMs, containing mainly Mode 2 Form 1 sectors: these (like all CD media) also contain 2352-byte physical sectors which contain 2048 bytes of data, a sync pattern, headers and EDC and ECC data, however it is arranged differently from Mode 1 CD-ROMs. On Linux, I only know how to read /dev/sr0, which has access only to the 2048-byte-sector data but not the raw ECC etc. by reading the file /dev/diskNs1 (or sometimes it's /dev/diskNs0, I don't know how Mac OS X decides whether to call it s0 or s1 - does anyone know?). by reading the file /dev/diskN, or the 2048-byte sector data they contain, e.g. On a Mac, it is possible to extract both the raw 2352-byte sectors, e.g. Virtual CD-Online eliminates all these hassles.Most physical data CD-ROMs I have come across have been Mode 1 CD-ROMs: these have 2352-byte physical sectors, each containing 2048 bytes of data, a sync pattern, headers and EDC and ECC data. To burn a disc, you would have to either burn the image to disc by hand or with specialized burners such as CD-ROM. It does this by mounting an image of your choice as an iso disk on your windows server using any optical disc drive of your choice such as a DVD drive or CD writer. Virtual CD allows you to access your files on your Windows server without actually burning them to disc. When you install Virtual CD, it first creates a log on virtual drives that can be accessed by any administrator on the network. If you are wondering how Virtual CD does its job, here are the basics. Windows also includes Virtual CD backup software, which allows you to create and save your backup image in a simple but effective manner. All you need to know how to access your backed up data on a Windows system is to be able to access the Virtual CD through the command prompt window that comes installed in windows 7. You are able to create your own Virtual CD using Virtual CD-Online, burn the image and have it saved on any standard CD or flash drive. This is a software tool that provides you with a Virtual CD-Online in its most bare bones form. So far, Virtual CD-Online has revolutionized the way people protect their files. With a single low cost license, you are able to give access to all your valuable data to any server connected to the web. The latest in this line is the Virtual CD. A number of software companies are chomping at the bit to provide you with better tools for the protection of your valuable data files. If you think that Microsoft is the only player in town when it comes to providing the most popular form of digital media protection and administration, you would be mistaken.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |