Advantages of CD-R(i).Good for permanent data storage.(ii).Less expensive per disc than CD-RW disc (CD-R discs are cheaper compared to CD-RW).(iii).Readable on virtually all CD-ROM and CD-R drives.(iv).Use when you do not need to erase the data.(v).CD-R drives can write faster than most CD-RW drives.Disadvantages of CD-R.(i).The disc can only be written once, (i.e. once something has been recorded on a CD-R, itcan’t be erased or written over again).(ii).The future of CD-R drives seems to be in doubt since CD-RW drives can accomplish thesame thing as CD-R drives.Note. In a CD-R drive, there are 2 speeds listed.The faster of the two speeds is thespeed at which the drive reads information from a disc,whilethe slower one is thespeed at which the drive records information onto a CD-R.CD-RW(ReWriteable).It is possible to record data on a CD-RW more than once.With CD-RW drive you can also erasethe contents of a CD and re-write new information to it.In addition, CD-RW drives can play audio CDs, use the regular CD-ROMs & read CD-R discs.This makes CD-RW drives very desirable.Most CD-RW drives can also record to CD-R discs, making it possible to use CD-R discs with aCD-RW drive.Advantages of CD-RW.(i).Used when you need to erase the data and re-write new information (e.g., updating files).Data written to a CD-RW is not permanent, i.e. it can be overwritten or erased.(ii).Used to make a practice CD or to test the contents of a CD before making a permanent one.(iii).More cost effective for near line data storage requirements than CD-R.Disadvantages of CD-RW.(i).CD-RW drives & media are expensive/more costly than CD-R drives.(ii).CD-RW are slower than CD-R & CD-ROM drives.It takes about 1hr to format CD-RW discs & about½an hour to copy 250 MB of data to thedisc, while CD-R discs take a few minutes to format and have the same write time.(iii).Data can be read and written to CD-RW discs only by CD-RW drives.(iv).CD-RW drives are currently facing stiff competition from theDVD-Recordable(DVD-R)because the DVD-R can store more information than CD-RW.Note. Both CD-RW & CD-R can be read by standard CD-ROM drives.
WORM (Write Once Read Many) discs.A WORM disc looks like a CD.Also, data is read from the disk in a similar way to that on aCD.The WORM disc surface has 40,000 Tracks, 25 Sectors and a total storage capacity of 1GB.Data is written into the disc by burning a permanent pattern into the surface of the disc by meansof a high precision laser beam.The WORM discs are exchangeable.WORM discs are non-erasable & are less prone to data loss compared to Magnetic disks.Access speed of a WORM disc is slower than that of Magnetic disks.To use the WORM discs, aWORM disk unit/driveis needed.The drive is similar to magneticdisk unit.An example of a WORM drive is the CD-R, which uses the same size of disks as CDs and oncewritten using the CD-R drive, it can be read in a CD-ROM disk drive as well as in a CD-R drive.