CD-ROM

Short for Compact Disc-Read Only Memory, CD-ROM drives are CD players inside computers that can have speeds in the range from 1x and beyond, and have the capability of playing audio CDs and computer data CDs. Below is a picture of the front and back of a standard CD-ROM drive.

Interfaces
Below are the different types of Interfaces that allow a CD-ROM and other disc drives to connect to the computer.

• IDE / ATA - One of the most commonly used interfaces used still today to connect disc drives to the computer.
• Panasonic - Older proprietary interface.
• Parallel - Interface used with old external CD-ROM drives.
• PCMCIA (PC Card) - Interface sometimes used to connect external disc drives to laptop computers.
• SATA - Quickly replacing IDE as the new standard to connect disc drives.
• SCSI - It is highly recommended to get a card that matches the CD-ROM drive as some of the earlier drives had proprietary SCSI interfaces. Otherwise, a SCSI-2 card is recommended.
• USB - Interface most commonly used to connect external disc drives.

CD-ROM transfer speeds
Below is the standard transfer rates and access times of the majority of CD-ROM drives. The below figures are averages you can expect to find on each speed of CD-ROM drive. These averages may be slower or faster than your CD-ROM drive and to where the CD-ROM is accessing the data from the CD-ROM. In general the higher this number is the faster the transfer rate or in the case of a disc burner the faster the write rate.

Drive speed	Transfer rate (BPS)	Access time (ms)
Single-speed (1x)	153,600	400
Double-speed (2x)	307,200	300
Triple-speed (3x)	460,800	200
Quad-speed (4x)	614,400	150
Six-speed (6x)	921,600	150
Eight-speed (8x)	1,228,800	100
Ten-speed (10x)	1,536,000	100
Twelve-speed (12x)	1,843,200	100
Sixteen-speed (16x)	2,457,600	90
Eighteen-speed (18x)	2,764,800	90
Twenty-four-speed (24x)	3,686,400	90
Thirty-two-speed (32x)	4,915,200	85
One-hundred-speed (100x)	15,360,000	80
CAV drives (12x - 24x)	1,843,200 - 3,686,400	150-90