Browse Prior Art Database

CLOCK SHIFT REGISTER IN FLOPPY DISC DRIVE CONTROLLER

IP.com Disclosure Number: IPCOM000023476D
Original Publication Date: 1977-Dec-31
Included in the Prior Art Database: 2004-Mar-31
Document File: 2 page(s) / 219K

Publishing Venue

Xerox Disclosure Journal

Abstract

When writing data on a track sector, a data address byte is recorded preceded by 6 bytes of binary zeros. The data address byte has selected clock pulses missing. A clock shift register of 8-bit length is included in the controller. During the time zeros are written, the register is loaded with the proper clock pattern for the data address byte. Once the data address byte has started to be written, the register shifts out and is reloaded with binary ones so that all following bytes will have clock bits present.

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XEROX DISCLOSURE JOURNAL

CLOCK SHIFT REGISTER IN FLOPPY Proposed Classification
DISC DRIVE CONTROLLER U~S~C1~ 340/174R
Robert Swenson Into Cl. Glic 11/02

I DISK 1 FLOPPY

    DRIVE ________ DISK
[~ONTROLLERf DR~VE

When writing data on a track sector, a data address byte is
recorded preceded by 6 bytes of binary zeros. The data
address byte has selected clock pulses missing. A clock shift
register of 8-bit length is included in the controller.
During the time zeros are written, the register is loaded with
the proper clock pattern for the data address byte. Once the
data address byte has started to be written, the register
shifts out and is reloaded with binary ones so that all
following bytes will have clock bits present.

During a read mode, all clock bits are shifted through the
register and a comparator compares its contents with a
umissing clock pattern~ of the data address byte. At the

proper time, the comparator is checked to see if the missing

clock pattern is received, Then, the pattern being compared
against is changed to all ones and every subsequent data byte
is checked to make sure all clocks are present.

Volume 2 Number 6 November/December 1977 97

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                    XEROX DISCLOSURE JOURNAL
98 Volume 2 Number 6 November/December 1977

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