US3864735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Read/write system for high density magnetic recording
Assignee: Unisys Corp
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Filing: 1973-09-12
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Granted: 1975-02-04
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Expires: 1993-09-12
Abstract
Abstract A method and apparatus for encoding and decoding binary data for writing and reading on a moving storage medium, the data being encoded according to a self-clocking code such as the modified frequency modulated (MFM) encoding scheme, provides high density data storage with high speed data retrieval. Non-return to zero (NRZ) encoded data is encoded into MFM data for storage, with the use of a write clock signal that is responsive to the speed variations of the storage medium. The write clock signal, sector mark signals and a storage medium speed indicating signal are synthesized from an index signal generated in response to the speed of the storage medium. The storage medium speed indicating signal is utilized by a multi-mode read clock recovery circuit to generate a read clock in response to the reading of the MFM encoded data. This read clock is utilized to generate asymmetrical data windows for decoding the MFM encoded data read from the storage medium into NRZ encoded data.
Inventors
- 👤 Martin F Davis
- 👤 Francis J Schwanauer
- 👤 Ivan E Walenta
- 👤 Gary J Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:54
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/16; G11B20/14; G11B20/1403; G11B20/1423
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
151 words
In a system for reading and writing self-clocking binary encoded data on a moving storage medium having data writing and reading apparatus and apparatus for generating a signal indicating the speed of said storage medium, binary data encoding and decoding apparatus, comprising: means responsive to the speed indicating signal for generating write clock signals; means utilizing the write clock signals for encoding input binary data, encoded according to a non-self-clocking encoding scheme, into a self-clocking binary data pattern for writing on the storage medium; means responsive to the storage medium speed indicating signal and the self-clocking binary data pattern read from the storage medium for generating read clock signals; means responsive to the read clock signals for generating asymmetrical data windows; and, means utilizing the asymmetrical data windows for decoding the self-clocking binary data pattern read from the medium into a binary data pattern representative of the nOn-self-clocking input binary data.
Claim 2
Dependent Claim
151 words
In a system for reading and writing self-clocking binary encoded data on a moving storage medium having data writing and reading apparatus and apparatus for generating a signal indicating the speed of said storage medium, binary data encoding and decoding apparatus, comprising: means responsive to the speed indicating signal for generating write clock signals; means utilizing the write clock signals for encoding input binary data, encoded according to a non-self-clocking encoding scheme, into a self-clocking binary data pattern for writing on the storage medium; means responsive to the storage medium speed indicating signal and the self-clocking binary data pattern read from the storage medium for generating read clock signals; means responsive to the read clock signals for generating asymmetrical data windows; and, means utilizing the asymmetrical data windows for decoding the self-clocking binary data pattern read from the medium into a binary data pattern representative of the nOn-self-clocking input binary data.
Claim 3
Dependent Claim
40 words
The binary data encoding and decoding apparatus of claim 1 wherein said means for generating write clock signals synthesize the write clock signals from a digital storage medium speed indicating signal and generates an analog storage medium speed indicating signal.
Claim 4
Dependent Claim
28 words
The binary data encoding and decoding apparatus of claim 1 wherein said means for encoding is adapted to encode NRZ encoded binary data into MFM encoded binary data.
Claim 5
Dependent Claim
73 words
The apparatus of claim 3 wherein said encoding means, comprises: a plurality of D-type flip-flops for receiving the NRZ encoded binary data and the write clock signal, a combinatorial logic circuit responsive to said plurality of D-type flip-flops for generating control pulses; and a D-type flip-flop connected as a toggle, responsive to the control pulses from said combinatorial logic circuit for generating the MFM encoded equivalent of the received NRZ encoded binary data.
Claim 6
Dependent Claim
144 words
In a system for reading and writing self-clocking binary encoded data on a moving storage medium, a method of encoding input non-self-clocking encoded data into self-clocking encoded data, for writing on the moving storage medium, and for decoding self-clocking encoded data read from the moving storage medium, said method comprising: generating a signal indicating the speed of said storage medium; responsive to the speed indicating signal, generating write clock signals; responsive to the write clock signals and the input non-self-clocking encoded data, generating self-clocking encoded data; responsive to the speed indicating signal and the self-clocking encoded data read from the storage medium, generating read clock signals; responsive to the read clock signals, generating asymmetrical data windows; and, responsive to the asymmetrical data windows and the self-clocking encoded data read from the medium, generating a binary data pattern representative of the input non-self-clocking encoded data.
Claim 7
Dependent Claim
144 words
In a system for reading and writing self-clocking binary encoded data on a moving storage medium, a method of encoding input non-self-clocking encoded data into self-clocking encoded data, for writing on the moving storage medium, and for decoding self-clocking encoded data read from the moving storage medium, said method comprising: generating a signal indicating the speed of said storage medium; responsive to the speed indicating signal, generating write clock signals; responsive to the write clock signals and the input non-self-clocking encoded data, generating self-clocking encoded data; responsive to the speed indicating signal and the self-clocking encoded data read from the storage medium, generating read clock signals; responsive to the read clock signals, generating asymmetrical data windows; and, responsive to the asymmetrical data windows and the self-clocking encoded data read from the medium, generating a binary data pattern representative of the input non-self-clocking encoded data.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |