Short for Compact Disc-Read Only Memory, a CD-ROM (shown right) is an optical disc which contains audio or software data whose memory is read only. A CD-ROM Drive or optical drive is the device used to read them. CD-ROM drives have speeds ranging from 1x all the way up to 72x, meaning it reads the CD roughly 72 times faster than the 1x version. As you would imagine, these drives are capable playing audio CDs and reading data CDs. Below is a picture of the front and back of a standard CD-ROM drive.
Below are the different interfaces that allow a CD-ROM and other disc drives to connect to a 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 (Mbit/s)||Access time (ms)|
|Single speed (1x)||1.2288||400|
|Double speed (2x)||2.4576||300|
|Quad speed (4x)||4.9152||150|
|Six speed (6x)||7.0653||150|
|Eight speed (8x)||9.8304||100|
|Ten speed (10x)||12.288||100|
|Twelve speed (12x)||14.7456||100|
|Eighteen speed (18x)||21.8343||90|
|Twenty speed (20x)||up to 24.576||90|
|Thirty-two speed (32x)||up to 39.3216||85|
|Thirty-six speed (36x)||up to 44.2368||80|
|Fifty-two speed (52x)||up to 63.8976||80|
|Seventy-two speed (72x)||up to 88.4736||75|
|CAV drives (12x - 24x)||1,843,200 - 3,686,400||150-90|
- Further information about the "x" on a CD-ROM drive speeds can be found on our x definition.
- What does max mean on 24x max CD-ROM drive?
- Listing of CD-ROM and other disc drive manufacturers.
- Computer CD-ROM and disc drive help and support.