Patent
Adaptive data compression apparatus including run length encoding for a tape drive system
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TLDR
In this paper, the adaptive data compression apparatus is used to efficiently compress a user data file received from a host computer into a bit oriented compressed format for storage on the magnetic tape that is loaded in the tape transport.Abstract:
The adaptive data compression apparatus is located within a tape drive control unit which is interposed between one or more host computers and one or more tape transports. The adaptive data compression apparatus functions to efficiently compress a user data file received from a host computer into a bit oriented compressed format for storage on the magnetic tape that is loaded in the tape transport. The data compression apparatus divides each block of an incoming user data file into predetermined sized segments, each of which is compressed independently without reference to any other segment in the user data file. The data compression apparatus concurrently uses a plurality of data compression algorithms to adapt the data compression operation to the particular data stored in the user data file. A cyclic redundancy check circuit is used to compute a predetermined length CRC code from all of the incoming user data bytes before they are compressed. The computed CRC code is appended to the end of the compressed data block. The data compression apparatus operates by converting bytes and strings of bytes into shorter bit string codes called reference values. The reference values replace the bytes and strings of bytes when recorded on the magnetic tape. The byte strings have two forms, a run length form for characters that are repeated three or more times, and a string form that recognizes character patterns of two or more characters.read more
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References
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Patent
High speed data compression and decompression apparatus and method
TL;DR: In this paper, a data compressor compresses an input stream of data character signals by storing in a string table strings encountered in the input stream, where each string comprises a prefix string and an extension character where the extension character is the last character in the string and the prefix string comprises all but the extension characters.
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Data compression using run length encoding and statistical encoding
TL;DR: In this paper, a run length encoding scheme using a flag byte symbol which is disposed between a character signal and a running length symbol was proposed. But this scheme was not suitable for the use of large numbers of characters.
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TL;DR: In this article, a data compaction system and apparatus is described, which, in the preferred embodiment, includes a high speed compaction controller utilizing both read only storage and read-write storage.
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TL;DR: In this article, an input data string including repetitive data more in number than the specified value is transformed into a data string having a format including the first region where non-compressed data are placed, the second region including a datum representative of a compressed data string section which has undergone the compression process and information indicative of the number of repetitive data.