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Disk Drive Page

A 3 1/2 inch (3.5") floppy may contain 720, 1440 or 2880 Kbytes of data. They are commonly called a 720 or three-and-a-half or three-point-five inch drive, One point four four or high density three-and-a-half, and a two-point-eight-eight drive respectively. While the higher capacity drives will work with the lower capacity disks (1.44Mbyte works with 720K disks) the reverse is NOT true. This is called backward compatibility, a phrase you will hear often repeated in computer jargon.

The media is contained within a rigid case but is itself flexible. Thus, this is not a hard drive but a floppy drive. NEVER touch the media or the disk will be ruined. To view the actual media, slide open the metal door and look through the read/write window.

The back of the drive has power and data connections. Some 3.5" floppy drives have non-standard connectors and must have adapters to connect with the data cable. The power connector will normally attach only one way. This makes it difficult to plug power in wrong. Pin one of the data connector is usually at the end of the connector next to the power connector. Wire one on the ribbon cable is most often marked with a different color, usually red, from the others and the connector has a small arrow or triangle marking pin one of the connector. This information should help if you are installing a used floppy to an existing system or if you have no documentation. Refer to the manufacturer's installation instructions before making any installation. The Internet allows you to download information on much of the old, used equipment that is out there. Always remove all power connections, including modem phone lines, before working inside your computer.

Three disks Disks with media bared

5 1/4 inch (5.25") floppy drives may contain from 180 Kbytes to 1.2 megabytes of storage. The most common varieties are the 360Kbyte and 1.2 megabyte drives. The 360 Kbyte drive is a double-sided, double density (DSDD on the box at the store) drive while the 1.2 megabyte drive is a double sided, high density (DSHD) drive. As with the 3.5" floppy drive, the 5.25" drive is backward compatible with lower capacity disks.


The 5.25" disks are what everybody thinks of as floppy disks. This is because they, well, flop and flex. NEVER bend the disk or the media will be ruined. The square disks have open read/write (windows) holes where you can actually see the media. NEVER touch the media or the disk will be ruined. This allows debris (or fingerprints) to attach to the disk, causing damage that destroys the disk's information. Another problem is that squashing or bending the disks can destroy the media. That is why you never write directly on a 5.25" disk label with anything but a soft felt-tipped pen (use ball-point BEFORE putting the label on the disk). It is also responsible for the overwhelming popularity of the 3.25" floppy with its rigid protective case and covered read/write window. AOL couldn't send 5.25" disks through the mail with certainty that the software would survive.

CD-ROM (Compact Disk Read Only Memory)drives are very popular, and for good reason. The drives have become inexpensive to buy and the disks are cheap to make (figure, under two dollars to press a disk). A software maker can put information onto software that looks at the disk and verifies that it is being accessed from the CD. This can be used to prevent software piracy. CD-ROM disks can hold 640 Megabytes of data, more than any application on the market today is likely to need. You don't need 16 3.5" high density disks to load up your favorite suite of office apps.

CD ROM and Drive

The disks require special care. Like 5.25" floppies the media is exposed. Unlike floppies, you can clean them. Refer to your CD-ROM drive manual for sections on cleaning the disks. Soft, lint-free, clean cloths only should be used. While I don't recommend it for software CD's, I have put my music CD's under the tap and washed them in dish soap, then dried them using a soft, clean, lint-free towel. While it worked great, I don't recommend it. It could void a warranty.

The attachments for a CD-ROM drive are nearly identical to those for a 3.5" floppy, and with the same layout. In addition, a sound cable attaches to the CD and runs to a sound card. To get the drive to work properly, you may be called on to move a jumper to master or slave selection as required by your system. Again, refer to your manufacturer's manual for proper installation and troubleshooting.

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Updated January 24, 1998, 10:52pm.