GB1481789A - Data retrieval arrangements - Google Patents

Data retrieval arrangements

Info

Publication number
GB1481789A
GB1481789A GB5064973A GB5064973A GB1481789A GB 1481789 A GB1481789 A GB 1481789A GB 5064973 A GB5064973 A GB 5064973A GB 5064973 A GB5064973 A GB 5064973A GB 1481789 A GB1481789 A GB 1481789A
Authority
GB
United Kingdom
Prior art keywords
transitions
transition
data
marker
address
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB5064973A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EMI Ltd
Original Assignee
EMI Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EMI Ltd filed Critical EMI Ltd
Priority to GB5064973A priority Critical patent/GB1481789A/en
Publication of GB1481789A publication Critical patent/GB1481789A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B17/00—Guiding record carriers not specifically of filamentary or web form, or of supports therefor
    • G11B17/005—Programmed access to indexed parts of tracks of operating discs, by guiding the disc
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/14—Digital recording or reproducing using self-clocking codes
    • G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
    • G11B20/1423—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/102—Programmed access in sequence to addressed parts of tracks of operating record carriers
    • G11B27/107—Programmed access in sequence to addressed parts of tracks of operating record carriers of operating tapes

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)

Abstract

1481789 Reproducing digital data EMI Ltd 21 Oct 1974 [31 Oct 1973] 50649/73 Heading G4C In a system for reproducing self clocking digital data stored as transitions on a medium (e.g. magnetic tape), a marker address code preceding each block of data includes a portion in which two adjacent transitions are separated by a time in excess of the maximum time which normally separates transitions. As described a binary "1" is represented by a transition at the middle of a cell period T and a binary "0" by no transition except when followed by a further "0" when a transition occurs at the start of a bit cell. The maximum time between the transitions is then 2T=T M . An address marker is derived by omitting the central transition in the code 1001, this giving an interval of 3T between successive transitions. An interval in excess of 4T is taken to indicate absence of data. To correct for skew in data recorded in parallel channels the address marker may be simultaneously recorded on all channels, each channel being read out to an associated shift register.
GB5064973A 1974-10-21 1974-10-21 Data retrieval arrangements Expired GB1481789A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB5064973A GB1481789A (en) 1974-10-21 1974-10-21 Data retrieval arrangements

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5064973A GB1481789A (en) 1974-10-21 1974-10-21 Data retrieval arrangements

Publications (1)

Publication Number Publication Date
GB1481789A true GB1481789A (en) 1977-08-03

Family

ID=10456781

Family Applications (1)

Application Number Title Priority Date Filing Date
GB5064973A Expired GB1481789A (en) 1974-10-21 1974-10-21 Data retrieval arrangements

Country Status (1)

Country Link
GB (1) GB1481789A (en)

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Legal Events

Date Code Title Description
PS Patent sealed
746 Register noted 'licences of right' (sect. 46/1977)
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee