CD-ROM

Short for Compact Disc-Read Only Memory, CD-ROM drives or optical 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.

Computer CD-ROM drive

Interfaces

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

  • IDE/ATA - One of the most commonly used interfaces for disc drives.
  • 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 - Replacing IDE as the new standard to connect disc drives.
  • SCSI - Another common interface used with disk and disc drives.
  • USB - Interface most commonly used to connect external disc drives.

CD-ROM transfer speeds

Below is the standard transfer rates and access times for CD-ROM drives. The below figures are averages you can expect to find on each speed of CD-ROM drive.

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

Related pages

Also see: CD terms, Storage device