CD-ROM

(redirected from 4x CD-ROM)
Also found in: Dictionary, Thesaurus, Medical.

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
..... Click the link for more information.
.

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 ?
Multimedia PC, Windows 95 or higher, 486 or higher, 8MB RAM, 256 SVGA monitor, 4x CD-ROM drive.
Requires an IBM or compatible with Pentium processor running Windows 95 or Windows NT 4.0, with 8 MB RAM, 4x CD-ROM drive, 800 x 600 screen resolution with 16-bit color, 16-bit sound card and speakers, mouse.
Even the wonderful ISDN line that nobody can afford is approximately eight times slower than even a 4x CD-ROM drive (Table 1).
Component shortages also plagued 4X CD-ROM drive manufacturing in mid-1995 for about a six month period, resulting in a glut of the drives at the beginning of this year, said analysts.
Windows 98/2000 Professional/Me/XP, Pentium 200MHz (300MHz rec.), 32MB for Windows 98 & Me (64MB rec.), 64MB for Windows 2000 & XP, 330MB avail, hard disk space, 4x CD-ROM drive min., SVGA, 16-bit min.
Requirements: At least 100 MHz Pentium computer, Windows 98 or higher 32 MB hard-disk space, 4x CD-ROM drive, $59.
System requirements: 266 MHz Pentium or faster, 64 MB of RAM, 350 MB of hard-drive space, 4X CD-ROM drive, 8 MB 3D video card, minimum 28.8 KBps modem (which allows four-player games on Internet/LAN), Windows 95/98, DirectX 7.0 (provided with game).
Multimedia PC, 486/66 processor or faster, 16MB RAM, 4x CD-ROM drive, MPC sound card, 16-bit video card, Windows 95 or higher.
If you are using text-oriented bibliographic databases in your library, the 2x and 4x CD-ROM drives are as good as today's fastest CD-ROM drives.
Its new entry-level Ready system, which features a 120MHz Pentium processor, 8Mb of RAM, a 1.2Gb hard drive, 28.8Kbps data, fax and voice modem, and 4x CD-ROM drive, is expected to have a street price $1,799.
They bought a Zeos Pantera, a 90 MHz Pentium with 16 MB RAM, 850 MB IDE hard disk, 64-bit video card with 2 MB RAM, 15[inches] monitor, 16-bit, 44 KHz wavetable synthesis audio card, and a 4x CD-ROM drive.