Record track identification and following

DETAILED DESCRIPTION It is therefore an object of the present invention to provide an improved servo sector pattern in a flexible disc memory wherein the addresses of the record tracks is embedded in the servo blocks.
This is accomplished by encoding all addresses as a constant energy value, thereby enabling the use of the servo blocks for both record track identification and null servo track following.
It is another object of the invention to generate position error signals in a track follow mode in such a manner as to provide improved repeatable servoing of the transducer.
This is accomplished by implementing a particular position error signal algorithm which substantially eliminates the ambiguity between odd and even record tracks from one servo sector to the next as the flexible disc rotates.
The flexible disc record member according to the invention is provided with servo track follow integration areas within the servo sector areas.
The servo track follow integration areas comprise an equal number of signal bursts representing binary "1" and binary "0", respectively, and these signal bursts are arranged in a predetermined pattern according to a sliding modulo code.
More particularly, the sliding modulo code is characterized by the insertion of one of two binary codes, which exhibit high self-correlation properties, at positions within the integration areas corresponding to a consecutive number of signal bursts equal to a digit in an address identifying a particular track location line.
The two binary codes are complements, are composed of an odd number of signal bursts and are selected so as to maintain equal the number of signal bursts representing "1's" and "0's" in the servo track follow integration areas.
The transducer positioning system used in cooperation with this flexible disc is provided with circuitry having a search mode for detecting addresses of the record track location lines and a servo mode for centering the transducer with respect to a selected one of the record track location lines