S
sector
A logical segment of information on a particular track. The smallest addressable unit of storage on a disk. Tracks are made of sectors.
sector pulse signal
A digital signal pulse present in hard sectored drives which indicates the beginning of a sector. Embedded servo pattern or other prerecorded information may be present on the disk when sector is active.
seek
A random access operation by the disk drive. The act of moving a set of read/write heads so that one of them is over the desired cylinder. The actuator or positioner moves the heads to the cylinder containing the desired track and sector.
seek complete signal
A digital signal level which indicates that the positioner is not moving and is located over a cylinder or offset position.
seek time
The amount of time between when a step pulse or seek command is issued until the head settles onto the desired cylinder. Sometimes is measured without settling times.
sequential access
The writing or reading of data in a sequential order such as reading data blocks stored one after the other on magnetic tape. This is contrasted to random access of information.
servo burst
A momentary servo pattern used in embedded servo control systems usually positioned between sectors or at the end of a track.
servo control
A technique by which the speed or position of a moving device is forced into conformity with a desired or standard speed or position.
servo head
A magnetic head designed specifically for accurately reading servo data.
servo pattern
A readback signal that indicates the position of a head relative to a track.
servo surface
A recording surface in a
servo system
An automatic system for maintaining the read/write head on track; can be either “open loop,”
GLOSSARY
servo track
A track on a servo surface. The prerecorded reference track on the dedicated servo surface of a disk drive. All data track positions are compared to their corresponding servo track to determine “off track”/”on track” position.
settling time
The time it takes a head to stop vibrating, within specified limits, after it reaches the desired cylinder.
silicon
Semiconductor material generally used to manufacture microprocessors and other integrated circuit chips.
small computer system interface (SCSI)
An intelligent interface that incorporates controller functions directly into the drive.
S.M.A.R.T. capability
soft error
A data error which can be overcome by rereading the data or repositioning the head.
soft sectored
A technique where the controller determines the beginning of a sector by the reading of format information from the disk. This is contrasted to hard sectoring where a digital signal indicates the beginning of a sector on a track.
software
Applications programs, operating systems, and other programs (as opposed to hardware).
spindle
The rotating hub structure to which the disks are attached.
spindle motor
The motor that rotates the spindle and therefore the disks.
sputtered media
Magnetic disk or tape that has the magnetic layer deposited by sputtering means.
stepper motor
A motor that has known detent positions where the rotor will stop with the proper control in some cases. The digitally controlled motor moves the head positioner from track to track in small,
storage capacity
The amount of data that can be stored in a memory location, usually specified in kilobytes for main memory and floppy drives and megabytes for mass storage devices.
storage density
Usually refers to recording density (BPI, TPI, or a combination of the two.)
storage location
A memory location, identified by an address where information may be read or written.
GL – 7