Why "floppy"? | How do they work? |
The importance of floppy drives |
Drive size and capacity | PC vs. Mac drives |
Can PCs and Macs share disks?
In an era of multimegabyte hard drives, it's hard to imagine that computers once depended on floppy disks for all of their storage needs. But it's a fact, and even though you may rarely use your floppy disk drive today, it's still an integral part of your computer system.
Floppy disks are a quick and convenient medium for backing up small data files or transferring information between computers. Floppies also serve as a way to transport new software. Most important of all, floppies provide emergency first aid. If your computer's hard drive fails, you can still get the machine up and running by starting it from a floppy disk that contains the operating system software.
Looking at the hard plastic case of today's 3.5-inch floppy diskettes, you've probably asked yourself, "Why do they call this thing a floppy?"
That's because the disk itself is a thin, round disk of flexible Mylar or other plastic coated with a magnetic medium that stores information as digital ones and zeros. Unlike a hard disk, which has a fixed metal platter, a floppy disk can bend. You can see the disk itself if you carefully slide back the metal shield on the business end of the plastic casing. The disk would flop if you could get your hands on it, but the case is designed specifically to keep that from happening. The 5.25-inch floppy disk, which predated 3.5-inch diskettes, was sheathed in a flexible square jacket -- and it flopped plenty.
Like a hard disk, a floppy has a magnetic coating much like the coating on a cassette tape. When your computer wants information from a floppy disk, an electromagnetic head inside the drive moves across the disk surface. It finds the place where the data is stored, reads the information and sends it to the microprocessor. The drive head writes information to the floppy disk in a similar fashion.
The drive head takes its orders from a floppy disk controller. Today, the controller is usually part of the same circuit board that controls your hard drive. Most computers can handle a maximum of two floppy drives without special software or a special controller.
Floppy drives are much slower than hard drives. Unlike hard drives, they don't run all the time. They only start turning when your computer needs to use them. You can tell when this is happening because the drive will click on and make subtle grunting noises. Some drives have an activity light that blinks when the drive is in use
When you turn your computer on, the first thing it does is check the floppy drive to see if it contains a disk. If there's no disk in the floppy drive, the computer will load the operating system from the hard drive. This is known as "booting up."
If the computer finds a disk in the floppy drive, it will try to load the operating system from the floppy. If it doesn't find the operating system on the floppy disk, you'll see an error message, or, in the case of Macintoshes, the computer will spit out the floppy and move on to the hard disk.
This may seem like a strange way to do things, but there's method to this madness: If the computer tried to boot up from the hard disk first, it would stop cold if the hard disk were damaged. There would be no way to get the machine running. Because the computer always tries the floppy drive first, you can always get your computer working by having a copy of the operating system on a floppy disk.
Today's computers use high-density floppy drives that are 3.5 inches in diameter and store up to 1.4 megabytes of data on a disk. That's more than enough room for the average novel, but only a fraction of what it takes to store today's large programs. That's why new software usually arrives on multiple floppy disks or a CD-ROM.
Super-high-density 3.5-inch drives that can store up to 2.8 megabytes of data are also available, but they haven't become popular.
Some older computers have so-called "double-density" drives that can store only 720 kilobytes of information. You can use a 720K disk in a high-density drive, but you can't use a high-density disk in an older drive.
Home computers built through the early 1990s were often equipped with 5.25-inch drives, or a combination of 5.25- and 3.5-inch drives. The older, 5.25-inch disks, which were encased in flexible black cardboard sleeves, also came in high-density and double-density models. They could store 1.2 megabytes and 360 kilobytes of data, respectively.
You can install any kind of 3.5- or 5.25-inch drive in today's PCs, but there's no need for a 5.25-inch drive unless you have to swap disks with someone who has an older computer without a 3.5-inch drive. The new, smaller drives are faster and more reliable than the old ones, anyway.
Although both Macintosh and IBM-compatible computers use 3.5-inch floppy drives, they handle those drives differently.
Once the computer is running, a PC doesn't pay attention to the floppy drive until it needs to access a file or write information to the disk. You can insert and remove a disk at any time using a mechanical eject button. If you remove a disk at the wrong time and the PC needs information from it, the result is an error that can sometimes cause programs to crash.
Macintosh computers, on the other hand, constantly monitor the floppy drive. When you insert a disk, the Mac will try to read it automatically. Once it figures out what's on the disk, it will display an icon for that disk on your desktop.
Apple didn't put an eject button on the Mac's floppy drive so you wouldn't remove a disk at the wrong time. Instead, you have to use the operating system to tell the Mac to eject the disk. This keeps the number of disk errors down, but if the system crashes, you can be stuck with a disk in the drive and no apparent way to get it out. That's why Apple put the tiny hole next to the disk drive. If you insert the end of a paper clip into the hole and press it just right, the disk will eject, even if the computer is off.
The answer is yes and no. Although they use the same kind of 3.5-inch diskettes, Macintosh computers and PCs format their data in two different, incompatible formats.
Newer versions of the Macintosh operating system can read and write to PC-formatted disks. However, to read a Mac disk with a PC, you'll have to buy a special utility program. If you need to exchange data between Macs and PCs, this is good way to do it.
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