GB1481789A - Data retrieval arrangements - Google Patents
Data retrieval arrangementsInfo
- 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
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.
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) |
-
1974
- 1974-10-21 GB GB5064973A patent/GB1481789A/en not_active Expired
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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 |