What are CD Drives?

How do they work?

This is historical information ....... Knowing about CD drives, how they work and their uses is important.

What are CD Drives?

They are disc drives which read Compact Discs (CDs). They are versatile and transportable and can be used to perform various tasks such as reading data from the computer and listening to audio. Click here to view some CD drives.

Data is written on a CD by burning pits into the disc to produce non-reflective areas.

Data is also written to a CD-R by changing the reflectivity of the coating on the surface of the disc.

When purchasing a CD-ROM drive, you should consider the drive specifications, the interface required for connecting to the computer and the formats it is capable of reading or writing.

Some of the formats used by CD-ROM drives are ISO 960, High Sierra, CD-DA, CD+, PhotoCD and CD-ROM-XA.

The type of CD drive that you buy should depend on what you will be using it to do (read or read and write) and also, the types of CD media that it will support.

CD drives are at various speeds - 2X, 3X, 4X .... 52X and so on.... The higher the speed the faster the drive will read or write data. The newer multi-speed drives enhance the performance of your system but are usually more expensive.

CD drives are called optical drives (optical technology/laser technology).

Originally, the CD-ROM standard was made as a 'read-only' medium. But, eventually, due to ever-increasing technology advancements, a writable CD format was 'born'.

What is a Compact Disc (CD)?

CD is the acronym for Compact Disc. It is an optical disc which is used to store digital data. It was originally invented for storing digital audio.

The CD was initially introduced to replace LP records and are excellent media for the storage of music.

A CD is a simple piece of thin round plastic which measures approximately 4.7 inches in diameter and can hold approximately 700 megabytes (MB) of data.

If you would like to be able to store large amounts of data, CDs are the way to go. Compact discs are now being used as a storage media for data, music, video, etc.

The most common types of digital media storage are (a) CD-ROMs which are used to store computer data and (b) CDs which are used by the music industry to store digital recordings. They are both 'Read Only' which means that the recorded data can only be read or played.

From the computer standpoint, a compact disc is a type of optical disc storage media which comes in various formats. These formats include:

• CD-ROMS which are 'read only'.
• CD-Rs which can be written to once and then 'read only'. They cannot be erased or recorded upon.
• CD-RWs which can be written to numerous times. CD-RW discs can only be played back on CD drives that are playback-compatible. These are very popular to the computer user for making music CDs and backing up data.

CDs are so easy and cheap to make that if you own a computer and a CD-R drive, you will be able to make your own CDs with any data that you want!

CD-ROM Drives

A CD-ROM (Compact Disc Read Only Memory) drive is a computer hardware device that can read (Read Only) data from a CD-ROM disc. You will not be able to write to this drive; neither can you copy or save files to them.

CD-ROM drives are either IDE, EIDE or SCSI.

IDE - Integrated Device Electronics -It has an interface for hard disk drives and CD-ROM drives. Less expensive than SCSI but it is slower. EIDE - Newer version of IDE.
SCSI - Pronounced 'SKUH-zee' and sometimes called "scuzzy". Allows personal computers to communicate with peripherals such as a CD-ROM drive.

CD-ROMS can be either internal and fit in a drive bay or, external in which case it will normally connect to the computer's SCSI interface or parallel port. Parallel port CD-ROM drives are easier to install but they are not cheap.

Today, most software is shipped on CD-ROMs because they hold much more data than a floppy disk and they are cheaper to make. The average CD can hold data that would require approximately 400 plus 3.5 floppy disks to store.

CDs are stronger than floppy disks and are not as vulnerable to get damaged from magnets.

Speed is one of the most notable features of the CD-ROM. When purchasing a CD-ROM drive, the data transfer rate and the access rate should be considered.

The data transfer rate describes the amount of data that the drive will be able to read from the CD and transfer to the computer in kilobytes per second. The transfer rates will vary depending on the speed of the drive. The speed that you will need will depend on what you will be using the drive for.

If the CD-ROM drive will only be used for tasks such as installing new software, a lower drive speed will be sufficient but, if you will be using it for games and multimedia (that consists of audio and video), you will definitely need the fastest drive speed possible.

The access rate is measured by the amount of time between when the drive receives the read command and when the data is read.

If you want to get a drive with the best performance, you should consider a higher speed data transfer rate with a shorter access time.

CD Drives - CD-R and CD-RW

CD-R: (Compact Disc Recordable) drives enable you to make your own CDs (including audio). These drives are now standard equipment in new computers.

CD-RW: (Compact Disc ReWritable) drives allows you to write, erase and re-write hundreds of times.

There are benefits when using CDs to store your information:

• Stores a lot of data.
• Low cost.
• Easier to carry.
• Have a longer shelf life than other media.

CD-R Drives/CD Burners:
These CD drives are called CD-recordable or CD-R drives. CD-R means Compact Disc Recordable and can only be written to once and then it becomes 'Read Only'. This drive is also known as WORM - Write once/read many.

CD drives allow users to be able to create CD-ROMs and audio CDs; but, to be able to do this, the user will require a CD recording software package.

• CD-R Drives:
  CD-R Drives come in slower speeds than the standard CD-ROM drives and will read standard audio and data CDs. This type of drive can write to CD-R media but is unable to re-write to CD-RW media.

• CD Burners:
  These are cd drives which are used to produce discs that are readable in other CD-ROM drives and audio CD players. It records onto a recordable CD-R disc. Note: Writing files to a DVD or CD is known as burning since the 'burning' is done by a laser.

CD-RW Drives:
This is called a CD-rewritable or CD-RW drive. CD-RW means Compact Disc Rewritable. They cost a little more than the CD-R but has the advantage of repeatably being able to write data to a disc over and over again! It works just like a floppy disc except that it holds a lot more data.

Both the CD-RW and the CD-R drives are backward compatible which means that they can read standard data and audio CDs.

CD-RW is extremely popular with the computer user and is used to make music CDs and for backing up data.

Single Session vs. Multi-Sessions:
Many CD-RW drives have a very nice feature known as multisession recording. This allows the continuous adding of data to a CD-ROM over time. This will be very important to a user who wants to use this drive to create backups of CD-ROMs.

The customary CD format is known as single-session since everything that is to be put on that disc is placed all at once. There are, however, some newer CD formats that use more than one session and these are referred to as multi-session drives. This means that data can be written to the beginning of the disc and more can be added to the unused space later.

These drives work like floppy disks; the only difference is that the CD-RW drive holds much more data.

DVD/CD-RW Combo Drive:

The great advantage of this type of drive is being able to play your DVDs and, at the same time, have the capability of having a rewritable CD drive - all in one! DVD means Digital Versatile Disc.

It has a huge storage capacity but has the same physical dimensions as the CD-ROM and also has a faster data transfer rate.

An MPEG-2 decoder usually comes with a DVD and this allows you to be able to play full-length DVD movies, full-screen using your computer.

The DVD writable drives available are DVD-R, DVD-RAM, DVD+RW and DVD-RW.

Facts:
• CD-ROM drives can only read CDs. They cannot read or write DVDs.
• DVD-ROM drives can read both CDs and DVDs.
• CD writers (burners) can read and write CDs.
• DVD writers can perform all of the above - Read, write CDs and DVDs.

CD-Drives - Summary and Recommendations:

• If you will be playing a lot of DVDs, get a dedicated DVD-ROM drive. This will extend the life of your CD burner.
• CD-R only drives are now obsolete. Spend a few extra dollars and get a DVD-ROM/CD-RW combo drive.
• Get CD re-writable media for backing up or transferring data from one system to another.
• For permanent data back-up, get CD-R media.

Anyway, all you 'vintage' PC owners, if you intend to install applications that are presented on dvds or watch movies, you will need to install a dvd-rom drive.

Click here to read about the installation of a CD-ROM drive.

Click here to view some CD drives.

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