US3986208A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Data recording with high speed search capability
Assignee: Sykes Datatronics Inc
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Filing: 1974-10-21
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Granted: 1976-10-12
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Expires: 1994-10-21
Abstract
Abstract A system of and method for writing and reading data on magnetic tape records having the capability of searching for certain data files in which selected messages are written is disclosed. The files are written successively on the tape with a name block which identifies or describes the files and data block which constitute the files written alternately to constitute the file format. The file names are written at much less than the normal data density. When reading the files, search operations are carried on at high tape speed; the ratio of the high tape speed to normal tape reading speed being the same ratio as the ratio of the normal density of recording of the data block to the lower density of recording of the file names in terms of bits per linear inch. The bit rate produced while reading the file names at high speed is then exactly equal to the bit rate generated while reading data blocks at low speed. Searches for selected files are conducted by comparing file names read from the tape with the names of the selected files while the tape is transported at high speed. Reading is carried out such that only data produced at the normal bit rate is read out and decoded. Thus, the tape speed selected is determinative of whether a search mode or data reading mode of operation is employed; special decoding logic or tracks for obtaining address data when tapes are driven in high speed search modes being eliminated.
Inventors
- 👤 John R. Sykes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:21
CPC Classifications
G; G11; G11B; G11B27/00; G11B27/10; G11B27/102; G11B27/107
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
97 words
For use in apparatus for writing and reading data signals on a tape record medium, a system for providing different access times for different items of data, said system comprising means for writing data signals representing each of said different items at different successively higher densities on said medium, and means for reading said data signals from said tape when said tape is travelling at different successively lower speeds, each corresponding to a different one of said densities whereby to provide access to items of data written at the lowest of said densities in the shortest time.
Claim 2
Dependent Claim
97 words
For use in apparatus for writing and reading data signals on a tape record medium, a system for providing different access times for different items of data, said system comprising means for writing data signals representing each of said different items at different successively higher densities on said medium, and means for reading said data signals from said tape when said tape is travelling at different successively lower speeds, each corresponding to a different one of said densities whereby to provide access to items of data written at the lowest of said densities in the shortest time.
Claim 3
Dependent Claim
56 words
The invention as set forth in claim 1 wherein said reading means includes means for transporting said record medium at different speeds, the ratio of said different speeds being the inverse of the ratio of the densities corresponding thereto, whereby said data signals are all read from said tape record medium at the same repetition rate.
Claim 4
Dependent Claim
37 words
The invention as set forth in claim 2 wherein further means are included in said reading means for providing data output signals only in response to data signals read from said tape at said same repetition rate.
Claim 5
Dependent Claim
69 words
The invention as set forth in claim 2 wherein said writing means includes means for driving said tape when said data signals are being written thereon at the speed corresponding to the highest of said densities, and means for applying said data signals corresponding to said different items to said tape at different rates such that said different items are written on said tape at the density corresponding thereto.
Claim 6
Dependent Claim
80 words
The invention as set forth in claim 3 wherein said reading means includes means for changing the speed of travel of said tape from a higher to a lower of said speeds when certain data is read from said tape while said tape is travelling at said higher speed so as to present data, which is written on said tape at the density corresponding to said lower speed and is located adjacent said certain data, for read-out from said tape.
Claim 7
Dependent Claim
71 words
The invention as set forth in claim 5 wherein said speed changing means includes a first register for storing said certain data, and search logic means for comparing data read from said tape with said data in said register and providing an output in response to correspondence therebetween, and control logic means for operating said tape drive means to lower the speed of said tape when said last named output occurs.
Claim 8
Dependent Claim
59 words
The invention as set forth in claim 6 when said search logic means includes a second register, means for reading data signals from said tape with said tape travelling at said higher tape speed and storing said signals in said second register, and a comparator for comparing the data in said first and second registers for providing said output.
Claim 9
Dependent Claim
76 words
The invention as set forth in claim 3 wherein said writing means includes means for providing clock pulses at a plurality of different rates each corresponding to a different one of said densities, and means responsive to said clock pulses for writing said data signals onto said tape at the density corresponding thereto, said reading means including means responsive to said clock pulses having the highest of said different rates for providing said data output signals.
Claim 10
Dependent Claim
90 words
The invention as set forth in claim 8 wherein said data output signal providing means includes a buffer shift register, means for applying data signals read from said record medium to a data input of said buffer shift register, and means responsive to said highest rate clock pulses coupled to a shift input of said register for clocking data signals into and out of said register when such signals are applied to said data input thereof at the same nominal rate as the rate of said highest rate clock pulses.
Claim 11
Dependent Claim
49 words
The invention as set forth in claim 8 further comprising control logic means for selectively applying said clock pulses of different rates to said clock pulse responsive means and for providing control signals to said tape speed control means both in response to control data inputs to said apparatus.
Claim 12
Independent Claim
104 words
A method for providing rapid access to different data items recorded on a tape record medium which comprises the steps of writing said items and data descriptive of said items in alternate locations disposed along said tape with said items at a higher density than said descriptive data, and reading said tape at a first speed corresponding to said descriptive data density until the data descriptive of a selected one of said data items is read from said tape, and then reading said tape at a second speed corresponding to said higher density of said data items for reading said one selected data item.
Claim 13
Independent Claim
104 words
A method for providing rapid access to different data items recorded on a tape record medium which comprises the steps of writing said items and data descriptive of said items in alternate locations disposed along said tape with said items at a higher density than said descriptive data, and reading said tape at a first speed corresponding to said descriptive data density until the data descriptive of a selected one of said data items is read from said tape, and then reading said tape at a second speed corresponding to said higher density of said data items for reading said one selected data item.
Claim 14
Dependent Claim
69 words
The invention as set forth in claim 11 wherein said writing step is carried out by first transporting said tape at said second speed, and then writing said descriptive data at a first rate and said items at a second rate which bears to said first rate the same ratio as said first speed bears to said second speed, said second speed being much lower than said first speed.
Claim 15
Dependent Claim
93 words
The invention as set forth in claim 12 wherein said writing step further includes the steps of storing said signals representing descriptive data and said data items with the aid of a register and clocking said data signals representing said descriptive data out of said register with clock pulses having a first repetition rate and said data signals representing said data items with clock signals having a second repetition rate, said first clock pulse rate corresponding to said first writing rate and said second clock pulse rate corresponding to said second writing rate.
Claim 16
Dependent Claim
101 words
The invention as set forth in claim 11 wherein said reading step is carried out by transporting said tape at said first speed and reading data signals which are repetitive at a rate corresponding to the product of said lower density and said first speed, and then transporting said tape at said second speed and reading data signals which are repetitive at the same rate, said second speed being lower than said first speed and being such that the product of said second speed and said higher density is equal to the product of said first speed and said lower density.
Claim 17
Dependent Claim
65 words
The invention as set forth in claim 11 wherein said reading step further includes the step of comparing said descriptive data as said data is read from said tape with descriptive data corresponding to the selective data item, and changing said tape speed from said first and higher speed to said second and lower speed when said comparison indicates said descriptive data are the same.
Claim 18
Dependent Claim
26 words
The invention as set forth in claim 14 where said reading step further includes reading data from said tape into a first register at said rate.
Claim 19
Dependent Claim
71 words
The invention as set forth in claim 16 wherein said reading step further includes the steps of storing data corresponding to the descriptive data which in turn corresponds to the selected data item in a second register, comparing the data stored in said first and second registers, and changing the speed of said tape to said lower second speed when said comparison indicates the data in said registers are the same.
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) | 1979-10-12 | 1980-04-12 | 1980-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-12 | 1984-04-12 | 1984-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-12 | 1988-04-12 | 1988-10-12 | $7700.00 | Window Closed / Lapsed |