A CD-ROM drive (Compact Disk - Read Only Memory) is a type of device used by your computer to read CDs. These CDs are used for a variety of purposes such as installing software and playing music. I'm sure you have used one but may be wondering how exactly they work. In this computer tip we will explain how they work to give you a better understanding without going into too much detail to confuse... or bore you. This also applies to DVD drives as well although they work a little differently.

A CD-ROM drive operates by using a laser to reflect light off the bottom of the CD or disc. The reflected light pulses are read by a photo detector. These incoming pulses are decoded by the microprocessor and then sent as usable data to the rest of the computer where it is processed and used.


The CD-ROM drive gets its power from the computer’s main power supply. An IDE controller inside the computer sends instructions back and forth between the computer and the CD-ROM, telling the CD drive to send data to the computer. This is the same type of controller used with IDE hard drives. Some CD-ROMs use another type of data connection called SCSI which is a faster type of connection as well as the newer SATA connection commonly used with today's modern hard drives. The IDE controller sends and receives information to and from the drive using a 40 pin ribbon cable just like with a hard drive. CD-ROMs also send data over an audio cable that attaches to the sound card or to a sound port on the motherboard. Then the sound card sends the sound and music to the computer's speakers.

Data is stored on the disc as a series of tiny indentations or "pits". A laser is shined on to the reflective surface of the disc to read the pattern of pits and lands (the space between the pits). A standard 120 mm CD-ROM holds 650 or 700 MB of data depending on the type. By increasing the speed at which the disc is spun, data can be transferred at higher rates. The fastest transfer rate in use on current drives is 52x or 10,350 rpm which transfers data at 7.62 megabytes per second. CD-Recordable drives (CD-RW) are often labeled with three different speed ratings, one speed for write once operations, one for re-write, and one for read only. That’s why you see drives that say something similar to 52X/32X/52X as the speed rating.

Although the discs and the drives of the CD and CD-ROM are pretty much the same, there is a difference in the way data storage is organized. There are 2 modes for CD data storage. Mode 1 is for storing computer data and Mode 2 is for compressed audio or video data. The CD-ROM, like regular CDs, has data encoded in a spiral track beginning at the center and ending at the outermost edge of the disc. The spiral track holds 650 to 700 MB of data. A CD-ROM disc is made of an aluminized or gold flashed reflective material, with polycarbonate plastic for durability. Then the discs are given a lacquered or plastic coating.

Pin It

Join Us On FaceBook

We Recommend:



Join Us On Twitter

Get insights into the computer industry and regular updates on our site. Click Here

OCT Youtube Channel

New tech tip videos posted on a regular basis. Subscribe today! Click Here

Sponsored

LATEST VIDEOS

Cut Yourself Out a Slice of Data As you probably know...

Mount an ISO Image File in a VirtualBox VM Oracle Vi...

Find Your Wireless Password With Ease Many of us have...

3 Ways to Rename your Computer When you install Windo...

Create a Windows iSCSI Storage Server Microsoft Windo...

Learn about Windows 10 Safe Mode and recovery options ...

RECENT TIPS

Do you think your computer has a malware i...

How safe is your personal data?   Hacking...

Are your gaming skills up to par?   Onlin...

An easier way to scan PDF documents   If ...

Keep your computer safe while you are in school ...

How Icons Can Be Used in Website Design The S...

NEWS

Another reason to keep your devices up to date. If you ...

Try not to get the BlueKeep Blues Once again the Micros...

Are Your Chrome Credentials Secure? Many people like to...

Windows 10 Optional Updates Coming Soon If you can reme...

Is a Virtual Private Network right for you? &nb...

Use Some Cache to Speed Up Chrome If you use the popula...