GLOSSARY
strobe offset signal
A group of digital input signal levels which cause the read PLL and/or data decoder to shift the decoding windows by fractional amounts. Often early/late are modified when two signals are used.
T
thin-film head
A magnetic transducer manufactured by deposition of magnetic and electrical materials on a base material contrasted with prior art mechanical methods. Read/write heads whose read/write element is deposited using integrated circuit techniques rather than being manually wound.
thin-film media
See plated thin film media.
track
One surface of a cylinder. A path which contains reproducible information left on a magnetic medium by recording means energized from a single channel.
track-following servo
A
tracks per inch (TPI)
A measurement of radial density. Tracks per inch of disk radius.
track positioning
The method, both mechanical and electrical, used to position the heads over the correct cylinder in a disk drive system.
U
un-correctable error
An error that is not able to be overcome with Error Detection and Correction.
unformatted capacity
Storage capacity of disk drive prior to formatting; also called the gross capacity. (See format.) The raw capacity of a drive not taking into account the capacity loss due to storage of the format control information on the disk surfaces.
unrecoverable error
A read error falling outside the capability of an ECC mechanism to correct, or not able to be overcome by rereading the data in question, with or without repositioning the head.
V
voice coil motor
A positioning motor that uses the same principle as a voice coil in a loudspeaker. The motor has no detent positions. The mechanical motion output of it can be either rotary or linear.
W
Whitney head
A successor to the original Winchester read/write head design. The primary change was to make the flexure smaller and more rigid. First used in IBM 3370/3380.
Whitney technology
A method of constructing a read/write head in a rigid disk drive using a Whitney head. In all other details it is the same as Winchester technology.
Winchester head
The read/write head used in Winchester technology,
Winchester technology
A method of constructing a rigid disk drive using concepts introduced in the IBM model 3340 disk drive. The primary changes from prior technology was to lower the mass of the slider, use of a monolithic slider, radically changing the design of the flexure and having the slider come to rest on a lubricated disk surface when disk rotation ceases. In addition to the above, a totally sealed chamber containing the read/write heads and disks was used to protect against contamination.
window margin
The amount of tolerance a read/write system has for transition jitter at a specified error rate level.
word
A number of bits, typically a multiple of eight, processed in parallel (in a single operation). Standard word lengths are 8, 16, 32 and 64 bits (1, 2, 4, or 8 bytes).
write
The recording of flux reversals on a magnetic media.
write pre-compensation
The intentional time shifting of write data to offset the effects of bit shift in magnetic recording.
write gate signal
A digital input signal level which causes the drive circuitry to record (write) data.
GL – 8