CD-ROM

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Related to CD-ROM player: CD-ROM drive

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 ?
I also prefer an external CD-ROM player to one that's built into your computer.
Even before the network software was loaded, we needed to improve our memory management because the external CD-ROM player requires a device driver, the Microsoft CD-ROM extensions program, and the SETVER program (needed because MSCDEX does not know about versions of DOS later than 4.
Kodak, for instance, is promoting a photo CD; this device is much simpler than a CD-ROM player and could replace the slide projector as the standard for presentations.
1 CD-ROM player compatible with Microsoft Extensions
The following equipment is needed to use the Inside CD-ROM service: a 386 IBM or compatible PC with 512 KB of available RAM, approximately 5 MB of hard disk space, a CD-ROM player and controller card with Microsoft Extensions-compatible device driver, DOS version 3.
A "fast" personal computer with a triple-speed CD-ROM player.
Sony's new portable Multimedia CD-ROM Player (MMCD) integrates a CD-ROM XA drive, a DOS-compatible microprocessor, a 256-color LCD display panel, a speaker, a keyboard and a cursor pad in a two-pound package.
The Electronic Encyclopedia disc must be in the CD-ROM player and the separate KRS searching program on a floppy disk must be in the diskette drive.
8 software features hybrid CD support, enabling users to create CDs that can be read on a Mac or PC with a CD-ROM player or an audio CD player, and it also supports all the latest CD-R/RW drives on the market.
Among them were Seaborn Beck Weathers, a 49-year-old Dallas pathologist who described himself as a Walter Mitty type (he later lost an arm and the digits of his other hand, to frostbite), and Sandy Hill Pittman, a wealthy New York socialite who arrived with a satellite phone, two computers, a CD-ROM player, an espresso maker and ``stacks of press clippings about herself to hand out to the other denizens of Base Camp.
Two years ago they began promoting CD-ROM technology by offering a package consisting of a SCSI device and CD-ROM player bundled with CorelDRAW on CD-ROM.
Available for under $1,000, you can get a starter kit, which comes with a CD-ROM player and software.