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A hard drive, or hard disk, is the main source of memory in a computer; it contains a disk pack, which is made up of several disks stacked on top of one another. Each disk in the disk pack is magnetic, which allows it to store electronic data. To help segment and retrieve data on the disk, each disk is made of zones and cylinders that are responsible for holding information. On the disk itself, there are two heads for reading and writing information, and both are commonly used simultaneously. Old disk packs were large and did not have a case, while newer versions are fused into a case.
In a disk pack there are many disks, the number of which depends on how much memory is needed for the hard drive. To ensure the data affixes to the disks, each one has a strong magnetic force that can cling to data until the user erases the disk. At the same time, if the disks are exposed to other magnetic or electrical forces, then it can permanently delete data or render the disks inoperable.
When something is saved to a disk pack, it technically can throw the data anywhere, but this is inefficient. It would take the computer a long time to find the data, and it would make the hard drive unorganized. To segment data into easier-to-find and organized pieces, each disk has zones and cylinders. These memory addresses, which are like homes, can be accessed at any time so the person can use the data.
Each disk in a disk pack has two separate heads. The read head is used to look at the data and pull it up for the operator to use or look at. Write heads are used to magnetically fuse data with the disk. Both are commonly used simultaneously, which allows the user to save and display information at the same time without any processing errors.
While a disk pack is used in both new and old hard drives, and they function nearly the same, there is a large size difference. Old disk packs are around 10 to 12 inches (25.4 to 30.4 centimeters) wide and typically do not have cases. Newer disk packs are permanently fused into a metal hard drive case and are around 3.5 inches (8.9 centimeters) wide. The case surrounding newer disk packs shields the disks from dust and wear, which can ruin the information-storing capabilities.