read head


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read head

[′rēd ‚hed]
(computer science)
A device that converts digital information stored on a magnetic tape, drum, or disk into electrical signals usable by the computer arithmetic unit.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The EC Series Electrically Coded Interlock Switch and Control Unit consists of a uniquely coded actuator, a read head (switch), and a control unit capable of monitoring up to four switches for applications with up to four guard doors.
As the tape goes past the read head, a special servo pick-up head reads the signal level of the servo track, and causes microscopic adjustments to the vertical position of the head assembly on the fly to keep it on track.
In hard drives, for example, the damping process is important for the write head that generates field pulses, the media that switch to record the field pulses as a magnetization pattern, and for the read head sensors that detect the fields from the recorded pattern.
An optical read head averages the reflections from 80 scale facets and filters out signals that do not match the scale period.
The Tristar is built with a 30mW GaAs laser and, by optimizing the instrument's read head and the spatial characteristics of the laser beam, the unit has three times the signal-to-noise of the previous 20mW-based instruments.
IBM gave a taste of future hard disc data storage capabilities earlier this month when it demonstrated an advanced version of its GMR read head able to read and write at realistic data rates against a drive carrying 20 Gb of data per square inch.
This passage is accompanied by figures showing the general construction of optical disk media, read head design, and diffuse and focused laser reflections from optical disk media.
The presence of a mark is detected by measuring the amount of light reflected from the surface of a form as it passes under a read head. The forms must be custom-designed, however any type of paper can be used since the mark is a surface entity; the thickness, color, weight and chemistry of the paper do not affect the reader's ability to determine if a mark is present.
Since the read head is above B.sub.s at time t.sub.s, A" can start reading B.sub.s at that time and complete reading it by time t.sub.s + R [is less than or =] t.sub.s + P, the earliest time A' can start processing B.sub.s.
Ian Read head, Deputy Chief Constable of Hampshire Police, said he did not want to live in a country with surveillance on every street corner.
Three of the encoders are shaft-type, while one uses a read head and a graduated ring that mounts to a machine element.
The data capacity of a computer's magnetic hard drive depends largely on the sensitivity of a detector, or read head, that's used to decipher its contents.