What's the difference between CD-R and CD-RW?

Helpline Q&A Directory

When formatted using Adaptec Direct CD, a CD-RW disc has a capacity of 493MB, whereas a CD-R disc has a capacity of 659MB. I can use either disc to back up, alter and read data in Explorer (Windows 98). Given that a branded CD-RW disc costs ú5 as compared with ú1 for a branded CD-R disc, is there any reason why I should use CD-RW? I believe that, unlike CD-RW, CD-R may not be readable on other drives, but this isn't important as I would only use the data on my own drive in case of hard disk failure.

Both CD-R and CD-RW discs should be readable in other computers. However, the other computer may need the Adaptec software installed on it before it can understand the format used to write the CD-RW.

The difference in capacity is due to the different formats used to store the data on the two types of media. The CD-R is being written in multisession format. It is not rewritable, which means that you can write to the disc a maximum of 99 times. Once the space has been used up it can never be reused, even after the data it contains becomes obsolete. The space available for writing will eventually dwindle to nothing.

The CD-RW has been formatted for 'packet writing', which allows it to be treated just like a hard disk. Although the total capacity may be less than that of a CD-R, you can delete and rewrite files on a CD-RW so it will always have that capacity. This gives the CD-RW a potentially longer useful life than a CD-R.