CD : Computer Hardware Buyers’ Glossary

Introduction

CDROM (Compact Disc Read Only Memory) or sometimes CD-ROM (Compact Disc — Read Only Memory). Computer programs come written on discs that look just like ordinary audio CDs. They can hold about 650 MB of data, or the equivalent of 433 floppy diskettes. A computer CD-ROM drive is much like one in a home stereo, except that it spins 2×, 4×, 8×, 12×, 16× or even 48× as fast. The speeds are exaggerated. They only apply to the outermost track and in burst mode. In practice drives won’t be anywhere near as fast as advertised. The faster it spins, the faster data can be read. With the appropriate cable, you can even play audio CDs (Compact Discs) on a computer CD-ROM drive. Digital CDs can be read, but not written on.

Difference between a CD (Compact Disc) and a DVD (Digital Video Disc)

CDs and DVDs (Digital Video Discs) look almost identical. DVDs were designed to be exactly the same size so you could play old CDss on new DVD players. Blanks will have the letters CD-R, DVD-R, DVD+R, DVD-RW or Blu-Ray Disc in pale writing on the top surface to help you tell them apart. Audio usually comes on CDs. Video comes on DVDs. High definition video comes on Blu-Ray DVDs. Small programs come on CD big ones on DVD Video DVDs are often copy protected. CDs are not. You can find out what you have by letting a disc copier program such as Power2Go have a sniff. Windows is no help. It thinks everything is a CD.

The important difference you cannot see: CDs hold 650 MB (enough for 74 minutes of uncompressed audio), DVDs hold 4.7 GB (7 CDs worth) and Blue Rays hold 50 GB (77 CDs ) on a dual layer disc.

labeling

There is no practical way to brand CDs with your name, or even with a serial number. Often a magic password comes with a CD , on a piece of paper you are bound to lose. Without the password, you can’t install (or re-install) the software. Use a red Sharpie fine tip permanent marker to write the password/serial number/key on the top side of the CD where you can’t lose it. Don’t apply any sort of sticky label since it may come off inside the drive, unless it is specially designed for CDs.

Drive Types

The two most common kinds of CD-ROM are SATA (Serial ATA), EIDE (Extended Integrated Drive Electronics) and SCSI (Small Computer System Interface). Unfortunately there are also several other proprietary types that cause nothing but trouble often bundled with sound cards.

Under The Hood

You would think CDs would play from the outside in, like vinyl LPs (Long Play recordings) but they start at the centre and work out. This seems odd given the outer tracks are longer than the inner. The advantage of this is it often leaves the outer tracks unused which are often smeared with fingerprints by people failing to pick up the CDs properly.

Tips

• If the CD will not eject, power off. Rebooting will not suffice.
• When you load a CD, wiggle it to center it is the well. Otherwise it could easily jam.
• Keep cords, e.g. headset cords, away from the DVD tray. It may suddenly open and close and catch it.
• Blank CDs are shipped with a protective clear plastic shield on top. You must never insert it into your CD drive, especially along with a CD blank. It will make a very alarming rattling noise and, of course, will abort the write. Just throw it away when you open the pack to avoid this common error.
• You can make your CD always be stable as R: by changing the drive letter assignment in Windows.
• Be careful discarding CDs. They may contain passwords, bank accounts, credit card info, identity theft info… A heavy duty shredder will destroy them.
• If you borrow a CD from the library and it skips, stalls, repeats etc., try cleaning it with some Windex. Wipe it clean with a freshly laundered microfibre cloth. Look at the surface at an angle to highlight the scratches and fingerprints to clean. Polish it with a clean Kleenex and dry it with puff of compressed air. If that does not work, make a copy of the CD with your computer and play that in your CD player. Computer CD readers are generally more patient and more clever at dealing with flaws that the players on audio equipment. Often you then have a perfect CD to play. If you have any CD causing trouble, copy it while you still can. This results in a new perfect master.
• If you are labeling a set of CDs, particularly a set of audio CDs, label them so you can read the disc number no matter how the CD is oriented, like the CD on the right.