A device that reads and writes data on a magnetic disk or tape. For writing, the surface of the disk or tape is moved past the read/write head. By discharging electrical impulses at the appropriate times, bits are recorded as tiny, magnetized spots of positive or negative polarity.

These are small areas on a storage device. A hard disk when formatted, is divided into tracks, sectors and clusters. Tracks are concentric circles around the disk. Sectors are segments of a track. Clusters are a set of sectors. A typical hard drive may have 30 or more tracks and 10 or more sectors per track.

This is a temporary storage area, usually in RAM. The purpose of most buffers is to act as a holding area, enabling the CPU to manipulate data before transferring it to a device. How the Buffer works (because of the slow Read/Write process): Programs keep track of data changes in the buffer Programs copy the buffer to a disk Example #1 in Word Processors: Buffers are used to keep track of changes to files. When file is saved, the word processor updates the disk file with the contents of the buffer. Example #2 Buffers are commonly used when burning data onto a compact disc, where the data is transferred to the buffer before being written to the disc.

A single track location on all platters making up a hard disk. The time a program or device takes to locate a single piece of information and make it available to the computer for processing. Sequential Access Refers to reading or writing data records in sequential order, that is, one record after the other. Direct Access Refers to the ability to access data at random. This is the opposite of sequential access. Disks are random access media, whereas tapes are sequential access media.

Short for small computer system interface, a parallel interface standard used by Apple Macintosh computers, PCs and many UNIX systems for attaching peripheral devices to computers. SCSI interfaces provide for faster data transmission rates (up to 80 megabytes per second) than standard serial and parallel ports. In addition, you can attach many devices to a single SCSI port, so that SCSI is really an I/O bus rather than simply an interface.

Abbreviation of either Intelligent Drive Electronics or Integrated Drive Electronics. An IDE interface is an interface for mass storage devices, in which the controller is integrated into the disk or CD-ROM drive.

Serial ATA is a serial link -- a single cable with a minimum of four wires creates a point-to-point connection between devices. Transfer rates for Serial ATA begin at 150MBps. One of the main design advantages of Serial ATA is that the thinner serial cables facilitate more efficient airflow inside a form factor and also allow for smaller chassis designs.

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