A zip drive is a type of removable disk storage capable of holding a moderate amount of computer information. Although it was embraced by many computer users when it was introduced in , it never replaced the 3. Rather, items such as rewritable digital versatile discs DVDs , rewritable compact discs CDs , and flash drives gained popularity and have virtually replaced the floppy disk. These storage devices have proven to be convenient and capable of holding large amounts of data.
Neither one of these techniques makes very good use of the surface of the disk. The main thing that separates a Zip disk from a floppy disk is the magnetic coating used on the disk. On a Zip disk, the coating is much higher quality see How Tape Recorders Work for some discussion on magnetic coatings. The smaller head , combined with a head positioning mechanism similar to that used in a hard disk , means that a Zip drive can pack thousands of tracks per inch on the track surface.
Zip drives also use a variable number of sectors per track to make the best use of disk space. Other formats may get more or less capacity from the same drives and disks. Data is generally written to floppy disks in sectors angular blocks and tracks concentric rings at a constant radius.
Some disk controllers can vary these parameters at the user's request, increasing storage on the disk, although they may not be able to be read on machines with other controllers. On the IBM PC, MSX and most other microcomputer platforms, disks were written using a Constant Angular Velocity CAV format, with the disk spinning at a constant speed and the sectors hold the same amount of information on each track regardless of radial location.
This was not the most efficient way to use the disk surface with available drive electronics; because the sectors have constant angular size, the bytes in each sector are compressed more near the disk's center.
A more space-efficient technique would be to increase the number of sectors per track toward the outer edge of the disk, from 18 to 30 for instance, thereby keeping constant the amount of physical disk space used for storing each sector; an example is zone bit recording. Apple implemented this in early Macintosh computers by spinning the disk slower when the head was at the edge, while maintaining the data rate, allowing kB of storage per side and an extra kB on a double-sided disk.
This higher capacity came with a disadvantage: the format used a unique drive mechanism and control circuitry, meaning that Mac disks could not be read on other computers. Apple eventually reverted to constant angular velocity on HD floppy disks with their later machines, still unique to Apple as they supported the older variable-speed formats.
Disk formatting is usually done by a utility program supplied by the computer OS manufacturer; generally, it sets up a file storage directory system on the disk, and initializes its sectors and tracks. For memory, see: How to find how much RAM is installed on a computer. If you would like to view additional information, right-click the drive and select Properties from the drop-down menu that appears. If you are running Windows or Windows XP, My Computer also displays the total size and free space for each of the drives in the main window.
If you want to view more information, and a graph of available space, follow the steps above. At the end of the directory listing, you see information similar to the example below. As you can see above, the hard drive has over 16 GB of free space.
0コメント