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By gradually slowing down their rotational speed (1800–600 rpm for NTSC and 2470–935 rpm for Hi-Vision) [23] CLV encoded discs could store 60 minutes of audio/video per side for NTSC and Hi-Vision (64 minutes for PAL), or two hours per disc. For films with a run-time less than 120 minutes, this meant they could fit on one disc, lowering the ...
Unlike CD-ROM drives, CD-i players are complete computer systems centered around dedicated Motorola 68000-based microprocessors and its own operating system called CD-RTOS, which is an acronym for "Compact Disc – Real Time Operating System". [6] [7] [8] [9]
One major drawback to these copy-protected discs is that most will not play on either computer CD-ROM drives or some standalone CD players that use CD-ROM mechanisms. Philips has stated that such discs are not permitted to bear the trademarked Compact Disc Digital Audio logo because they violate the Red Book specifications.
This allows a DVD drive to focus the beam on a smaller spot size and to read smaller pits. DVD lens supports a different focus for CD or DVD media with same laser. With the newer Blu-ray Disc drives, the laser only has to penetrate 0.1 mm of material. Thus the optical assembly would normally have to have an even greater focus range.
The CD-ROM itself may contain "weak" sectors to make copying the disc more difficult, and additional data that may be difficult or impossible to copy to a CD-R or disc image, but which the software checks for each time it is run to ensure an original disc and not an unauthorized copy is present in the computer's CD-ROM drive. [citation needed]
The last DVD-RAM Specification, DVD-RAM2 (also called RAM2 or Class 1), is not compatible with DVD drives that do not specifically allow reading DVD-RAM2 discs. [12] DVD-RAM2 medium was brought to the market in Japan, [13] [14] but was not launched worldwide. [15] Some high end products such as IBM System p mainframes require DVD-RAM instead of ...
60 mm disc, a round version of the business card, with comparable capacity (50 MB) In 1997, Dean Procter of Imaginet was offering business card sized square CDs with full screen hi-fi stereo video which played in quad speed CD-ROM or DVD drives with the centre well. A variety of laser cut shapes were developed. [2]
An optical disc is designed to support one of three recording types: read-only (such as CD and CD-ROM), recordable (write-once, like CD-R), or re-recordable (rewritable, like CD-RW). Write-once optical discs commonly have an organic dye (may also be a ( phthalocyanine ) azo dye , mainly used by Verbatim , or an oxonol dye, used by Fujifilm [ 4 ...