RAM, Hard Drives, CDs and other storage

Question: What’s the difference between RAM, ROM, hard disks, floppies & CDs?
More information: Computers never seem to have enough memory, the internal storage area of a computer. As larger and more complex multimedia programs become commonplace, many computers require more and more memory to run them. However, before you head out to the nearest computer store to buy more memory, here is a little background information to make the trip easier.

Short Term Memory

Every computer contains two types of memory: short term RAM (Random Access Memory) and long term (disks). Programs in your computer are permanently stores on disks. When you run a program, a copy of the program is taken from a disk and placed temporarily in RAM, which allows the processor (brain of the computer) quicker access to the program’s instructions. When you use a program to create a document, the document is also temporarily stored in RAM.

When you close a document it is erased from R AM and existence. Before closing you must tell the computer to "save" your document on a disk if you want to keep a copy of it. When you quit or exit a program it is also erases from RAM, but the original remains on the disk.

Speaking of erasing things, countless people have had to learn the hard way that RAM requires electricity to store information. Any interruption in power will erase everything stored in RAM. Yes, everything, although some programs will automatically save your document at specified intervals. Preferences for the "backup" version can usually be selected in the Setup or Preference menu of many programs. You can also buy special purpose backup utilities.

When discussing memory, it can never be said enough how important it is to save your work often and make backup copies of important data stored on a disk. In fact, for very important work, make more than one backup copy, and keep them in separate locations. (If someone steals your computer, or it dies, you could lose a great deal more than the hardware if there are no backups on hand.) Moreover, a computer, like a car, can’t run forever.

As one computer user who goes by the name ’Til’ put it, "There are two types of computer users: those who’ve lost data and those who will! Work hard, save often."

Long Term Memory

There are many different types of ’long term memory’ for data storage. Because of their size, hard disks are the primary long term storage device for most programs and documents, but floppy disks are still needed to transport things from one computer to another. Today’s hard disks can store almost 1000 times more than a high density floppy disk. Early computers used 5.25" floppy disks to store programs and documents. They were replaced by low density or double density 3.5" floppy disks, then high-density 3.5" floppy disks (diskettes).

Currently, CD-ROMs are available with much higher storage capacity than a floppy disk. Programs are becoming increasingly larger and companies have begun shipping them on one compact disk (CD) instead of several floppy disks. For most newer programs it is essential to have a CD-ROM drive.

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 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 Versatile (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.

Measuring Memory

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 better. 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.

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.