CD-ROM


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Related to CD-ROM: DVD-ROM

CD-ROM:

see compact disccompact disc
(CD), a small plastic disc used for the storage of digital data. As originally developed for audio systems, the sound signal is sampled at a rate of 44,100 times a second, then each sample is measured and digitally encoded on the 4 3-4 in (12 cm) disc as a series of
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.

CD-ROM

[¦sē¦dē ′räm]
(computer science)

CD-ROM

compact disc read-only memory; a compact disc used with a computer system as a read-only optical disk

CD-ROM

CD-ROM

(Compact Disc-Read Only Memory) A type of CD disc that can only be read, but not recorded. Used to store programs and data files, a CD-ROM holds 650MB or 700MB of data and employs a different recording format than the audio CD (CD-DA), from which it evolved. In the 1990s, the CD-ROM rapidly replaced the floppy disk for software distribution.

An audio CD player cannot read CD-ROMs, but CD-ROM drives can play audio discs. In practice, the term "CD" refers to all CD formats. The phrase "insert the installation CD" really means "insert the installation CD-ROM."

How CD-ROMs Are Made
CD-ROMs are made by "burning" a blank CD-R disc and sending it to a media manufacturer, which creates a master disc that is used to stamp out the required quantity. See CD-R and mini CD.

Pretty Slow in the Beginning
Back in the late 1980s, the first CD-ROM drives transferred data at 150KB per second. By doubling the spindle speed from 530 to 1,060 RPM, the transfer rate doubled to 300KB (2x). For several years thereafter, speeds increased until reaching 48x and higher, making the "1x" drive painfully slow by comparison. For details about speeds, see CD-ROM drives. Access times range from 80 to 150ms. See CD-R, CD-RW, DVD and optical disc.


Caddy Load and Tray Load
Earlier drives used a caddy. The disc must be inserted into the caddy, and the caddy inserted into the drive. Today, drives are caddyless. The disc is placed into a tray.




Caddy Load and Tray Load
Earlier drives used a caddy. The disc must be inserted into the caddy, and the caddy inserted into the drive. Today, drives are caddyless. The disc is placed into a tray.







Reading CDs and CD-ROMs
Digital data are carved into the disc as pits (low spots) and lands (high spots). As the laser shines into the moving pits and lands, a sensor detects a change in reflection when it encounters a transition from pit to land or land to pit. Each transition is a 1. The lack of transitions are 0s. There is only one laser in a drive. Two are used here to illustrate the difference in reflection.







References in periodicals archive ?
Manual de Defectos/Remedios en la Corrugacion, Sexta Edicion CD-ROM
Further guidance for the SAO is contained in the DISAM memo accompanying the distribution of the CD-ROM.
Lotte Hellinga also directed the plan to illustrate the ISTC on CD-ROM, launched in 1994 as Project Incipit, managed by Margaret Meserve.
Penn Jillette, the noisy half of Penn and Teller, is one of the voices on the new ``SkyTrip America'' CD-ROM, a trek through American history, which also features voices by basketball star Chris Webber and Irene Bedard, the voice of Disney's ``Pocahontas.
Notwithstanding the suggestions that follow, CD-ROM researchers ma,%, actually need to review the large number of existing results to find the one or more relevant tax authorities that could answer the research question.
The CD-ROM system is integrated with an online database for more current information.
The most common approach to CD-ROM research is to start with a client issue(s) and usually proceed to extract certain "keywords.
CD-ROM players are best described as audio CD players with extra features.
Hearst Brand Development and RFM Broadcasting are partnering to create and distribute a total of 150,000 custom CD-ROMs in the July issue of three Hearst magazines.
As the return is being prepared, a dialog box pops up from the planning CD-ROM and raises points for future discussion with the client.
These implementations make SafeDisc the most widely supported technology and the de facto standard for CD-ROM copy protection for consumer software and information publishers in the global market.
By using a stack of eight CD-ROM drives, it is possible to search through the entire library of letter rulings, administrative documents, official rulings and cases, and browse through those documents directly on point.