04929946 is referenced by 170 patents and cites 8 patents.

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.

Title
Adaptive data compression apparatus including run length encoding for a tape drive system
Application Number
7/308767
Publication Number
4929946
Application Date
February 9, 1989
Publication Date
May 29, 1990
Inventor
Tracy D Dyer
Aurora
CO, US
Neil L Thomas
Boulder
CO, US
John T O Brien
Lafayette
CO, US
Agent
Dorr Carson Sloan & Peterson
Assignee
Storage Technology Corporation
CO, US
IPC
H03M 7/48
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