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Optical Drives


There are several different kinds of optical disc storage media that are found on a computer. Starting well over a decade ago when the humble CD-Rom (Compact Disc read only memory) started to appear on more entry level computers optical drives have become a mandatory component on most computers. Originally designed for music storage and playback the format was soon adapted to hold any form of binary data and become perhaps the best and most popular method of distributing software such as games and applications. With the uptake of DVD (Digital Video Disc) into the computer market in a similar fashion the storage capacity of an optical disk went from 700mb (CD) to 7.95GB (Dual Layer DVD). Virtually all operating systems are distributed by CD or DVD today.

Newer technologies such as Blue-Ray and HD-DVD struggle to reign supreme in the war to be the next optical drive phenomenon however at this point the single layer DVD would have to be the most commonly used media in the home or office.

CD's and DVD's may be manufactured in a number of ways. Typically for mass production they are stamped but for home or office use a "blank" CD or DVD is "burnt", where a laser is used to affect changes to a dye layer in the blank media. This process is done using a CD or DVD burner which have become very common and quite affordable particularly over the last two or three years. When purchasing an optical drive you may be presented with a number of different choices-
  • CD-ROM - reads compact discs only
  • CD-R - writes and reads compact discs
  • CD-RW - can read, write and re-write compact discs
  • Combo Drive - can read write and re-write compact discs and also read DVD's
  • DVD-ROM - reads compact discs and DVD's
  • DVD-RW - Can read, write and re-write compact discs and DVD's
Optical drives must be connected to the computers motherboard by some method to work correctly and there are a number of different bus types to accommodate this. IDE (pronounced eye-dee-e) or SATA (pronounced sah-tah) are by far the most commonly used in personal computers and will be the ones documented on this web site. The image below shows the difference between the two.

Optical Drives - Comparing Connectors.
IDE Optical Drives - Connectors.IDE DVD or CD drives still have the older audio connectors, one being digital the other being analogue. These were used mainly for playback of audio disks and are obsolete. They usually connected to the computers mainboard or sound card audio-in header. New operating systems such as Windows XP and Vista transfer audio playback via the data or IDE connector instead and the audio connectors are no longer required. The next connector is the IDE cable.

If you examine the ribbon cable that plugs into your IDE connector on the drive you will see that it has three connectors on it and down one side of the cable there is a stripe, usually red, on the edge. This stripe corresponds with PIN 1 on the IDE connector and is there to make sure the cable is correctly oriented when plugged in. Usually the the connectors will also have a key and slot to make sure they are plugged in correctly. If this is not the case then pin one is the top right hand corner pin when looking at the connector face on. With the three connectors, one of course plugs into the motherboard and the other two connect to a hard drive, optical drive or other storage device so you can have two devices on one IDE channel. If you are using two devices on the IDE channel (on one cable) one must be jumpered to be a master and the other a slave or they will not work. This is not as complicated as it might sound although it does require a bit of planning if you have many drives to plug into your computer. If you have two IDE connectors on your motherboard consider putting your devices on different channels if you only have two of them, say one hard disk and a DVD burner. This will give a slight increase in speed when copying from one to the other. Finally, there is the power connector which provides power from the power supply to the drive. Simply plug it in.

SATA Optical Drive - Connectors.Connecting a Serial ATA DVD or CD drive or burner is much easier. Master or slave is not specified on SATA so it is a simple case of plugging in the data connector (the smaller connector) into the drive and the other end of the data cable into a spare SATA port on your mainboard. The power connector is the larger of the two connectors and you may need an adaptor to convert the SATA power cable to a standard molex connector that is used on most power supplies. With newer model power supplies this is not necessary as they have the appropriate connector but when buying a PC in components it is wise to check if the adaptor is necessary as it will save you a trip back to your computer shop.