How many times i can write in CD RW disk?
January 10, 2007 7:09pm CST
Seven times or more..
24 Jan 07
Many software manufacturers have switched from floppy disks to CD-ROMs. They did this because a CD-ROM can hold up to four hundred and fifty times more data than a floppy disk. Up to the year 1990, most individuals could not use CDs for storage, because the devices that are used to write on them were only available to big companies, and they were quiet expensive. In 1990, CD-R technology has been introduced to the people. CD-R stands for Compact Disk – Recorder. It is a write-once, read-many technology, (WORM), but users cannot erase or rewrite the CDs. Early versions of CDRs were expensive, and they had many bugs that still needed to be worked out. When they first came out, the recordable media cost about $20 each, and it can hold up to 650 megabytes of data. The way CD-ROMs are made is by creation of indentations or pits in the track surfaces. A laser aimed at the track reads the disk. The pits reflect light at a different intensity than the smooth surfaces. As the disk rotates, the changes in intensity are translated into information your computer can understand. The CD-R drives duplicate the process by heating a dye on the recording layer of the disk. CDs created with CDRs are comparable with all other CD-ROM drives, and CD-Players. The recording layer of a CD-RW consists of a phase-change alloy. On a new disk, this alloy exists in its crystalline state, which is more reflective. When the laser heats the alloy, the heated portion changes to an amorphous state, which is less reflective and corresponds to a pit in a regular CD. The alloy can be changed back to a crystalline state using a laser beam with less strength, which allows you to rewrite the CD. CD-RW disks cannot be read in all CD-ROM drives as the CDR disks. The reason for this is that CD-RW disks do not reflect as much of the laser’s light as a CD or a CDR disk. All the CD-ROM drives manufactured before 1997 cannot read the CD-RW disks, as well as some manufactured after 1997. There are some companies that started making multi-read CD-ROM drives, which can read CD, CDR, and CDRW disks. Although CDR and CDRW drives are very good for backing up data, they will not be as fast as your hard drive, or as fast as the newer CD-ROM drives. Most CDR and CDRW drives can write at 2X and read at 4X or 6X, depending on the model, which means that they will write with the speed of 300 kilobytes per second. Another important factor to be considered when buying a CDR or CDRW drive is how much cache memory it has build in. When a CDR and CDRW drives create a CD, they read a file, and they place part of it into the cache memory prior to writing. The more cache memory a CDR or a CDRW has determines the effectiveness of the drive. If the amount of cache memory is small, the drive will have to read the files on your hard drive a lot more, therefore slowing down the process of CD burning. In most CDR and CDRW drives slowing down is not allowed, and therefore whenever it takes too long to fetch a file you will get an error that will read "Buffer Underrun". This is the reason why all the documentation tells you to scan your hard drive for errors and defragment it prior to burning a CD. Defragmenting a hard drive places files in order, one after another, so the files can be accessed easier. Prior to buying a CDR or a CDRW it is important to choose which one is more useful to you. CDR drives are used for permanent storage, such as music CDs, presentations, pictures, etc. CDRW drives are useful when you are making scheduled backups of your hard drive, and you will need to rewrite the CD, and also if you are downloading files from the internet and you need to put them on CD and then modify them. There is another factor in buying a CDR or a CDRW. You will have to look at the interface your computer is using for your hard drive. If your computer is using SCSI (Small Computer Systems Interface) hard drive(s), then it will be better for you to buy a SCSI CDR or a CDRW. The reason for this is because SCSI host adapters can transfer data between SCSI devices without going through CPU and memory, therefore making it a lot faster than EIDE interface (Enhanced Integrated Drive Electronics). IF you just have an EIDE drives, then buying a SCSI CDR or a CDRW is no use to you because it will have to transfer data between two different controllers. When buying a CDR or a CDRW an important factor to consider is the recordable media. Right now, media for a CDR goes for about $3 a disk, when media for a CDRW cost about $20. At these prices, you can buy about 8 CDR disks for the price of one CDRW disk, therefore you can record 5.2 Gigabytes for the price of one CDRW diskette. When buying media, please note that you will never get the 650 megabytes on a CD. The reason for this is when you write a CD, the software has to create a file that tells your computer where files are located on a CD. That table takes up different amounts of space depending on the amount of data you are writing. If you are writing a full CD, you can only put 620 megabytes of data on it, and the other 30 megabytes is used for the file. If you are writing multiple sessions, the file will be an additional twenty megabytes per session. The same thing goes when you record music onto CDs. The label on a CD says you can record 74 minutes of music on it, while you can only record 65 minutes. When recording music, please note that each minute of music corresponds to about ten megabytes of space on the CD, and a file with the location of tracks is still needed. If while burning a CD you get an error, the CD usually becomes unusable. If you select too much data, you will get an error saying the CD is full. If you try to read that CD you will be able to do so, and maybe even see all the files there, the reason for this being that the allocation file was created prior to writing. When you try to copy any of those files you will get a message saying "Unable to read the CD in drive X:" Right before going to the store to get a CDR, please take a close look at your computer. For a CDR or a CDRW you will need a 5 and ¼ bay free in your computer, and if you want to buy a SCSI CDR or RW you will need an empty slot for the SCSI host adapter in your computer. If you do not have those, you may be required to purchase an external drive, which will cost you more money depending on the model. reference:http://zeus.eed.usv.ro/misc/mirrors/cc/cdrvsrw.htm