There exist various software packages for the mastering and burning of CD-R for all major platforms. Until recently, however, substantial technical expertise was necessary to produce CD-R.
On the PC and the Macintosh, CD-R mastering and burning software has become available that takes care of many of the low-level details automatically. Basically, CD-R software creates either a virtual or a real (many CD-R applications call this physical, although this is not correct) image of the CD-R to be produced. This image is not a bit-for-bit copy of the final CD-R, it only organises the filesystem to be copied to the CD-R so that it is identical to the final filesystem on the CD-R. In a virtual image, only the pathnames of the files to be put on CD-R are stored, so that the source files can remain in their original location. Virtual images are compact, so that multiple virtual images can be held on disk simultaneously, and files need not be stored redundantly which helps avoid having inconsistent file versions. The major drawback of virtual images is that the lookup of files via pathnames may not be fast enough for the burning process, especially with double or quadruple speed CD-R drives. A real image contains the source file (or filesystem) itself. Each real image thus requires free hard disk space at least as large as the contents of the final CD-R, and files are duplicated which may lead to inconsistent file versions.
True bit-for-bit copies of CDs cannot be held on hard disks because of the different physical structure of CD and hard disk. However, some CD-R applications map the physical contents of a CD to a single file on hard disk, allowing true 1:1 copies of almost any CD-format to be made.
Note: A very good provider of CD-R soft- and hardware documentation, demo versions of software, and even public domain or shareware CD-R software can be found at the CD Archive at http://www.cdarchive.com/.