US Patent 4,701,745

Number:	4,701,745
Title:	Data compression system
Filed:	03-Mar-1986 (06-Mar-1985 in GB)
Granted:	20-Oct-1987
Inventor:	Waterworth John R
Assignee:	Ferranti PLC GB, patent rights now acquired by Stac Inc.

Comment by FAQ:Algorithm now known as LZRW1.

I claim: 1. A data compression system comprising an input store for receiving and storing a plurality of bytes of uncompressed data from an outside source, and data processing means for processing successive bytes of data from the input store; the data processing means including circuit means operable to check whether a sequence of successive bytes to be processed identical with a sequence of bytes already processed, and including hash generating means responsive to the application of a predetermined number of bytes in sequence to derive a hash code appropriate to those bytes, a temporary store in which the hash code may represent the address of a storage location, and a pointer counter operable to store in the temporary store at said address a pointer indicative of the position in the input store of one of the predetermined number of bytes; output means operable to apply to a transfer medium each byte of data not forming part of such an identical sequence; and encoding means responsive to the identification of such a sequence to apply to the transfer medium an identification signal which identifies both the location in the input store of the previous occurrence of the sequence of bytes and the number of bytes contained in the sequence.