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US4152695A
Expired / Lapsed
US
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Method of writing information relating to faults in a magnetic recording medium
Assignee: Compagnie Internationale pour l'Informatique CII-Honeywell Bull SA
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Filing: 1977-09-21
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Granted: 1979-05-01
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Expires: 1997-09-21
Abstract
Abstract A magnetic recording disc includes a plurality of sectors, each of which includes a plurality of data tracks and a reference zone containing information for identifying the data tracks. Some of the sectors are standby sectors containing information which would normally be contained in the sectors containing the data tracks. The reference zones of all sectors contain binary fault indicating bits which indicate whether a particular sector contains faults, and parity bits having values dependent on the location of the parity bit and the value of the fault bit at the same location as the parity bit. A data processor commands a read out head for the disc to be located at a particular position. From the command position of the data processor and the value of the fault bit, the data processor computes an expected parity bit value. The expected parity bit value is compared with the parity bit value read from the disc to provide an indication as to whether the fault bit is accurate.
Inventors
- 👤 Gerard Democrate
- 👤 Claude Cardot
- 👤 Jacques Droux
- 👤 Andre Oisel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:53
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/08; G06F11/10; G06F11/1008; G06F11/1012; G06F11/1032; G11; G11B; G11B20/00; G11B20/10; G11B20/18; G11B20/1883; G11B2220/00; G11B2220/20
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
136 words
A method of writing information relating to faults in a magnetic recording medium, wherein items of information carried by a plurality of tracks are written in a plurality of sectors, each of said sectors including at least one reference zone containing information for identifying the tracks, some of the sectors being standby sectors containing information which would normally be contained in the faulty sectors, comprising writing into the reference zones of all the sectors fault-indicating information which indicates whether or not the sectors are faulty, the fault-indicating information in each sector including fault and parity bits, writing the value of the fault bits so they depend on whether the sectors contain faults, writing the value of the parity bits so they depend on the location of the parity bit and the value of the fault bits.
Claim 2
Independent Claim
136 words
A method of writing information relating to faults in a magnetic recording medium, wherein items of information carried by a plurality of tracks are written in a plurality of sectors, each of said sectors including at least one reference zone containing information for identifying the tracks, some of the sectors being standby sectors containing information which would normally be contained in the faulty sectors, comprising writing into the reference zones of all the sectors fault-indicating information which indicates whether or not the sectors are faulty, the fault-indicating information in each sector including fault and parity bits, writing the value of the fault bits so they depend on whether the sectors contain faults, writing the value of the parity bits so they depend on the location of the parity bit and the value of the fault bits.
Claim 3
Dependent Claim
33 words
The method of claim 1 further including writing the value of the parity bits so they are dependent on the numbers of the track and sector in which the parity bit is located.
Claim 4
Dependent Claim
57 words
The method of claim 1 wherein the magnetic recording medium is a magnetic disc having two recording faces, the number of reference zones ZRPij in a sector Si being equal to the number of tracks on each face, each zone being associated with a track j and including a fault bit BDij and a parity bit BCPij.
Claim 5
Dependent Claim
20 words
The method of claim 3 wherein the fault and parity bits are written into the beginning of each reference zone.
Claim 6
Dependent Claim
76 words
The method of claim 3 wherein the fault bits and parity bits are written into an individual cell containing first and second changes in magnetization polarity, each of said changes being capable of occupying one of only two predetermined positions within each cell, the value of the fault and parity bits respectively depending upon the relative positions occupied by the first and second changes in the magnetization polarity of two adjoining reference zones ZRPij and ZRPi(j+1).
Claim 7
Dependent Claim
29 words
The method of claim 5 further including writing an indexing flux at the beginning of the reference zone to enable the beginning of the reference zone to be identified.
Claim 8
Dependent Claim
29 words
The method of claim 4 wherein the fault bits BDij and the parity bits BCPij for sector i, track j, are the items of fault information for sector i+1.
Claim 9
Dependent Claim
112 words
A magnetic recording medium comprising a plurality of sectors located along the length of the medium, each of said sectors including a plurality of data tracks and at least one reference zone containing information for identifying the tracks, some of the sectors being standby sectors containing information which would normally be contained in sectors containing errors, the reference zones of all the sectors containing fault-indicating information which indicates whether or not the sectors are faulty, the fault-indicating information in each sector including fault bits which indicate whether the sectors contain faults, and parity bits having a value dependent on the location of the parity bit and the value of the fault bits.
Claim 10
Dependent Claim
112 words
A magnetic recording medium comprising a plurality of sectors located along the length of the medium, each of said sectors including a plurality of data tracks and at least one reference zone containing information for identifying the tracks, some of the sectors being standby sectors containing information which would normally be contained in sectors containing errors, the reference zones of all the sectors containing fault-indicating information which indicates whether or not the sectors are faulty, the fault-indicating information in each sector including fault bits which indicate whether the sectors contain faults, and parity bits having a value dependent on the location of the parity bit and the value of the fault bits.
Claim 11
Dependent Claim
29 words
The medium of claim 8 wherein the parity value is dependent on the number of the track and the number of the sector where the parity bit is located.
Claim 12
Dependent Claim
53 words
The medium of claim 8 wherein the magnetic recording medium is a magnetic disc, the number of reference zones ZRPij in a sector Si being equal to the number of tracks on each face, each zone being associated with a track j and including a fault bit BDij and a parity bit BCPij.
Claim 13
Dependent Claim
20 words
The medium of claim 8 wherein the fault and parity bits are located at the beginnig of each reference zone.
Claim 14
Dependent Claim
79 words
The medium of claim 10 wherein the fault bits and parity bits are located within an individual cell containing first and second changes in magnetization polarity, each of said changes being capable of occupying one of only two predetermined positions within each cell, the value of the fault and parity bits BDij and BCPij respectively depending upon the relative positions occupied by the first and second changes in the magnetization polarity of two adjoining reference zones ZRPij and ZRPi(j+1).
Claim 15
Dependent Claim
24 words
The medium of claim 12 wherein the first cell contains an indexing part to enable the beginning of the reference zone to be identified.
Claim 16
Dependent Claim
29 words
The medium of claim 12 wherein the fault bits BDij and the parity bits BCPij for sector i, track j, are the items of fault information for sector i+1.
Claim 17
Independent Claim
164 words
A method of checking whether information read from a magnetic recording medium is correct, said record including a plurality of data tracks and at least one reference zone containing information for identifying the tracks, some of the sectors being standby sectors containing information which would normally be contained in sectors containing errors, reference zones of all the sectors containing fault-indicating information which indicates whether or not the sectors are faulty, the fault-indicating information in each sector including: fault bits to indicate whether the sectors contain faults, and parity bits dependent on the location of the parity bit and the value of the fault bit at the same location; in a data processor controlling the location of a read out head, computing an expected value for the parity bit in response to the controlled position for the head and the value of the fault bit read by the head; and comparing the expected parity bit value with the read out value for the parity bit.
Claim 18
Independent Claim
164 words
A method of checking whether information read from a magnetic recording medium is correct, said record including a plurality of data tracks and at least one reference zone containing information for identifying the tracks, some of the sectors being standby sectors containing information which would normally be contained in sectors containing errors, reference zones of all the sectors containing fault-indicating information which indicates whether or not the sectors are faulty, the fault-indicating information in each sector including: fault bits to indicate whether the sectors contain faults, and parity bits dependent on the location of the parity bit and the value of the fault bit at the same location; in a data processor controlling the location of a read out head, computing an expected value for the parity bit in response to the controlled position for the head and the value of the fault bit read by the head; and comparing the expected parity bit value with the read out value for the parity bit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-04-30 | 1982-10-30 | 1983-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-30 | 1986-10-30 | 1987-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-30 | 1990-10-30 | 1991-05-01 | $7700.00 | Window Closed / Lapsed |