The one shortcoming of compact disks is that most CD drives can only read information that was stored on a CD in a factory, so you or I cannot store things on a CD. This is why they are sometimes called CD-ROMs (Read Only Memory). New CD drives are available that can read and rewrite information on a CDs, but they are still relatively expensive. They require a CD-ReWritable disk (CD-RW).
Zips, Tapes & DVDs
One of the latest types of disks to emerge, the "Zip' disk, looks like a floppy disk, but is closer to a portable hard disk. As more and more people make use of the multimedia features of new computers, documents may become too large to fit on a high density floppy disk. Zip disks, which are slightly larger and thicker than floppy disks, can store 100 times as much as a high density floppy disk. Zip drives are now a common feature in new computers.
Tape drives were designed to help people backup the contents of a hard disk. They work much like a tape recorder, which reads data from the hard disk and writes it onto a tape. Tapes can store up to several gigabytes (GB) of data, and newer, faster ones can store up to 20MB per minute.
They are used solely as backup, since it is relatively slow to access data from a tape. Because they are "sequential access" devices, to access one piece of information on the tape, you have to read all of the preceding data first. They are one of the cheapest mass storage alternatives.
Digital Video Disk (DVD). DVDs are presently only being used to store movies, hence the name, but people are beginning to refer to them as Digital Versatile Disks because they will soon be used to store a broader range of data. A DVD is similar in appearance to a CD, but can store considerably more. New CD drives are being made to read DVDs also.
In order to make decisions about memory easier, we should discuss how memory is measured. All memory is measured in bytes. It takes one byte of memory to store one letter, number, symbol etc. It took approximately 13 000 bytes to store this article. Other units related to a byte include a kilobyte (approx. 1 000 bytes), a megabyte (approx. 1,000,000 bytes) and a gigabyte (approx. 1,000, 000 000 bytes). (See chart.)
If you are constantly seeing messages like "Disk Full" or "Low on Memory" you may want to consider adding more memory to your computer, which will provide more space for larger programs and documents. Increasing the amount of RAM you have can sometimes help to increase the speed of your computer. The processor can access RAM faster than it can access other types of memory, so the more it can store in RAM the betta. If RAM is full the computer can slow down considerably. Other devices, such as printers, can also slow down if the amount of RAM they contain is small, relative to the size of documents they are working with.
* These sizes can vary.
When purchasing anything for your computer it is always wise to get advice from different sources. Memory is not the only thing that affects the speed of your computer. Also, sometimes it's more cost-effective to buy a new computer than to upgrade a very old one.
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