The hard disk is a device which stores all programs and data in the computer. Hence, the hard disk is referred to as the memory bank of a computer. The hard disk.memory is permanent so that the programs and data are not lost when the computer is turned off. Nowadays, the capacity of the hard disk is measured in Giga Bytes (GB). Earlier, the memory capacity of computers was limited to Mega Bytes (MB). But, today PCs having hard disks of capacities like 20 GB, 40 GB or 80 GB are popular. Larger the hard disk capacity, more the amount of software programs and information that can be stored in it. After having knowledge about the hard disk, let us now briefly discuss various components present in the hard disk assembly (HDA). The Hard Disk Assembly is a sealed metal unit, which contains components listed here under.
• The Platters: The platters are the actual disks inside the drive that store the data. Most drives have ,at least two platters. and the larger the storage capacity of the drive. the more platters there are. Each platter can store data on each side. so a drive with 2 platt-ers has 4 sides to store data.
• The Spindle and Spindle Motor: The platters in a drive are separated by disk spacers and are clamped to a rotating spindle that turns all the platters in unison. The spindle motor is built right into the spindle or mounted directly below it and spins the platters at a constant set rate ranging from 3.600 to 7.200 RPM (rotation per minute).
• The Read/Write Heads: The read/write heads read and write data to the platters. There is typically one head per platter side, and each head is attached to a single actuator shaft so that all the heads move in unison. When one head is over a track, all the other heads are at the same location over their respective surfaces. Typically, only one of the heads is active at a time, i.e., reading or writing data. The space between the platter and the head is so minute that even one dust particle or a fingerprint could disable the spin.
• The Head Actuator: All the heads are attached to a single head actuator, or actuator arm, that moves the heads around the platters.