Apparatus guaranteeing that a controller in a disk drive system receives at least some data from an invalid track sector

• US 4,825,403 A
• Filed: 04/29/1986
• Issued: 04/25/1989
• Est. Priority Date: 05/16/1983
• Status: Expired due to Term

• Current Assignee: Data General Corp. (Dell Technologies Inc.)
• Original Assignee: Data General Corp. (Dell Technologies Inc.)
• Inventors: Lippitt, Mark C., Gershenson, Edward, Lemone, Louis A.
• Primary Examiner(s): Williams, Jr., Archie E.
• Assistant Examiner(s): Coleman, Eric
• Application Number:
  US06/858,540
• Time in Patent Office: 1,092 Days
• Field of Search: 360/51, 360/37.1, 360/38.1, 369/59, 371/10, 364/200 MS File, 364/ 900 MS File
• US Class Current: 360/52
• CPC Class Codes: G11B 20/12 Formatting, e.g. arrangement of data block or words on the record carriers within interface between computers and data recorders G06F3/06
• CPC Class Codes: G11B 20/1426 conversion to or from block codes or representations thereof
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence

Abstract

An apparatus provides a sequence detected signal indicating that a synchronization sequence occurring at regular intervals in a stream of data has occurred or should have occurred. The apparatus includes logic for detecting the synchronization sequence, logic responsive to the detection logic for producing the sequence detected signal when the detection logic detects the sequence, and logic for producing the sequence detected signal at a fixed time after the synchronization sequence should have occurred. If the synchronization sequence did occur, the apparatus thus produces two sequence detected signals; however, the device receiving the sequence detected signal responds to the first sequence detected signal and ignores the second. If the synchronization sequence did not occur, the device receiving the sequence detected signal responds to the sequence detected signal produced by the logic responsive to the timing apparatus. The apparatus thus guarantees that the device receiving the sequence detected signal will always receive such a signal.

Claims

1. In a disk drive including

(1) a disk for storing information, said information being stored on said disk in track sectors, each of said track sectors including data, header information and a synchronization mark preceding said header information,

(2) means for reading said header information, synchronization marks and data from said disk, and

(3) a read-write processor for receiving said header information, synchronization marks and data from said disk,

apparatus for ensuring that said read-write processor processes some said data from track sectors which do not contain a valid synchronization signal, said apparatus comprising:

(1) synchronization mark detected signal providing means for receiving said synchronization marks, providing a synchronization mark detected signal in response to said synchronization mark, and providing said synchronization mark detected signal after said synchronization mark should have been received; and

(2) control means in said read-write processor means responsive to said synchronization mark detected signal for causing said read-write processor means to commence processing said data currently being read from said track sector in response to said synchronization mark detected signal and ignoring any further synchronization mark detected signal until said read-write processor means has finished processing said data currently being read.

2. In the apparatus of claim 1, and said wherein:

said synchronization mark detected signal providing means includes;

(a) detection means for receiving said synchronization marks from said reading means and outputting a detected signal in response to each one of said synchronization marks;

(b) first synchronization mark detected signal producing means connected to said detection means for receiving said detected signal and outputting said synchronization mark detected signal in response to said detected signal; and

(c) second synchronization mark detected signal producing means for producing said synchronization mark detected signal after said detection means should have received said synchronization mark.

3. In the apparatus of claim 2, and wherein:

said disk drive produces a sector pulse signal at the beginning of each said track sector; and

said second synchronization mark detected signal producing means includes first timing means responsive to said sector pulse signal for determining the time at which said detection means should receive said synchronization mark and said second synchronization mark detected signal producing means outputs said synchronization mark detected signal in response to said timer means.

4. In the apparatus of claim 3, and wherein:

said read-write processor further includes second timing means responsive to said sector pulse signal for determining a first time period in which said detection means should receive said synchronization mark; and

said synchronization mark detected signal providing means includes enabling and disabling means responsive to said second timing means and to said synchronization mark detected signal for enabling said detection means during said first time period in which said detection means should receive said synchronization mark and disabling said detection means in response to said synchronization mark detected signal.

5. In the apparatus of claim 4, and wherein:

each said track sector includes a second synchronization mark following said header information;

said disk drive further includes means for writing said data to said track sectors;

said read-write processor processes said data being read from or written to said track sectors;

said disk drive is connected to controller means for receiving said data from said disk drive and providing said data to said disk drive and providing control signals including header/data control signals specifying alternatively the provision of said header to said controller or the transfer of said data red from or to be written to said data section between said controller and said disk drive, said controller means including header compare means for determining whether said header received from said disk drive is valid and changing said header/data control signal to indicate that said data is being transferred when said header received from said disk drive is valid;

said second timing means is further responsive to said header/data control signal and further indicates a second said period when said header compare means changes said header/data control signal to indicate that said data is being transferred between said controller and said disk drive;

said enabling and disabling means enables said detection means during said second time period; and

said second synchronization mark detected signal producing means produces said synchronization mark detected signal after said detection means should have received said first synchronization mark.

6. In a storage system for storing data including

(1) a disk drive including

(a) a disk for storing said data, said data being stored on said disk in track sectors including valid and invalid track sectors, each one of said valid track sectors including

(i) a first synchronization mark,

(ii) a header following said first synchronization mark;

(iii) a second synchronization mark following said header identical to said first synchronization mark, and

a data section following said second synchronization mark,

(b) read-write means for reading said synchronization marks and said data from said disk and writing said data to said disk, and

(c) a read-write processor for receiving said synchronization marks and performing operations including a header read operation and data transfer operations on said data, and

(2) a controller connected to said disk drive for receiving said data from and providing said data to said disk drive, said controller including

(a) header compare means for performing a header compare operation on said data received from said disk drive as a result of said header read operation and providing a header valid signal if said data is a valid header and

(b) means responsive to said header valid signal for providing a header/data control signal specifying alternatively the provision of said header to said controller and the transfer of said data between said controller and said disk drive to said disk drive, said means responsive to said header valid signal responding to said header valid signal by providing said header/data control signal specifying the transfer of said data between said controller and said disk drive,

apparatus for ensuring that said header compare operation is performed once for each said track sector to which said data is written or from which said data is read, said apparatus comprising;

(1) synchronization mark detected signal providing means responsive to said header/data control signals for receiving said data and said synchronization marks, providing a synchronization mark detected signal in response to said first synchronization mark when said header/data control signal specifies provision of said header to said controller, providing said synchronization mark detected signal after said first synchronization mark should have been received, and providing said synchronization mark detected signal in response to said second synchronization mark when said header/data control signal specifies transfer of said data between said controller and said disk drive; and

(2) control means in said read-write processor means responsive to said synchronization mark detected signal for causing said read-write processor means to perform said header read operation in response to the first said synchronization mark detected signal received after said read-write processor means begins processing each said track sector and one of said data transfer operations in response to the first said synchronization mark detected signal received after completion of said header read operation.