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Write Wide Read Narrow Disk File

IP.com Disclosure Number: IPCOM000081386D
Original Publication Date: 1974-May-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Paton, A: AUTHOR

Abstract

The block diagram shows schematically part of a servo-controlled magnetic disk file incorporating a write wide, read narrow feature. A number of data heads 1 are ganged for movement to a servo head 2, which derives position information from servo tracks recorded on servo disk 3. The position information is in the form of an error-voltage signal, which indicates by its magnitude and polarity the degree of offset of the servo head 2, and consequently the data heads 1, from the on-track position. The error voltage is amplified by amplifier 4 and supplied as one input to comparator 5.

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Write Wide Read Narrow Disk File

The block diagram shows schematically part of a servo-controlled magnetic disk file incorporating a write wide, read narrow feature. A number of data heads 1 are ganged for movement to a servo head 2, which derives position information from servo tracks recorded on servo disk 3. The position information is in the form of an error-voltage signal, which indicates by its magnitude and polarity the degree of offset of the servo head 2, and consequently the data heads 1, from the on-track position. The error voltage is amplified by amplifier 4 and supplied as one input to comparator 5.

In this apparatus the write operation to produce a wide data track requires two cycles. The data is first written with the data heads displaced to one side of the true on-track position, and then rewritten with the data heads displaced by an equal amount to the other side of the true on-track position. This is achieved by supplying first a positive off-set voltage and then a negative offset voltage to the other input of comparator 5. The positive offset voltage is supplied from a first write unit 6, which is connected to the input of the comparator by a switch 7 in its upper position.

The output from the comparator 5 is a voltage equal in magnitude to the difference between the servo error voltage from amplifier 4 and the offset voltage from write unit 6. This difference voltage is applied to a driver 8 which energizes an actuator 9 to move the heads in...