Abstract: An N-way set associative data cache system comprises a cache controller adapted to receive a request for data and instructions. The cache controller includes a cache buffer register for storing the requests for a line of information in the form of a page tag address and line address. The line address is stored in the buffer register as a pointer into a directory associated with each of the N-ways for determining where the line being accessed resides. If the page tag address matches one of the page entry addresses in one of the directories, there is a hit, but if not, the line of data must be fetched by a cache fill request. The line of data is retrieved from an L2 cache or main memory and written into the line of one of the ways at the line address being accessed. A novel LRU ordering tree or look-up table is provided for determining concurrently the one line in the number of N-lines in the cache to be replaced with the new line of data in the event of a miss.

Abstract: In a system for enhancing the integrity of transmitted data files from one memory to a remotely located memory there is provided an original data stream which is compressed by a known data compression code. The compressed data stream may be in a variable length format and is not provided with the usual parity code bits. To assure that compressed data is received both without loss and error free, the compressed data stream is divided into groups of n blocks having N bytes. At the end of the group of nN byte blocks, a block or check code is inserted into the compressed data stream. The transmitted and received compressed data stream is processed as n blocks of N bytes having a received block check code. The received blocks of data are used to generate new block check codes which are compared with the transmitted block check codes to determine if a one bit error has occurred in any of the n blocks of N bytes.

Abstract: In a data decompression system of the type having a self-compiling dictionary for building or replicating codes used for decoding incoming code values, there is provided a decoded string dictionary or memory for storing plural characters representing decoded strings. The decoded strings may be stored in a modified dictionary replacing string codes or stored in a separate variable length memory as blocks of characters having predetermined length and accessed using a finder memory. If the decoded string becomes too long to be stored in a fixed length memory, a conventional decoder dictionary may be used to reduce the size of the strings stored for direct access and read out to a recovered data stream.

Abstract: In a system for economically and continuously transmitting data files from one location to a remote location there is provided a high speed mainframe computer adapted to read a data file and to determine if the process to be performed on the data requires a large amount of mainframe processor cycle time. If so the data file is down loaded to a memory accessible by a much less expensive single chip type dedicated computer that is particularly well suited to perform the process that would require high mainframe processor time cost. The output of the dedicated computer in coupled to a communication network for transmittal to the remote location. In the preferred embodiment-of the present invention first-in-first-out (FIFO) data queues are employed to maintain optimum utilization of the dedicated computer and transfer of the data files.

Abstract: The present invention provides a novel method and system for obtaining maximum system speed performance for compressing coded data characters in a serial data stream by replacing strings of data with code values stored in a dictionary when strings are first observed as unique strings in the data stream. A novel pointer address is generated to represent new strings to be searched in the dictionary. The novel pointer address comprises a string code portion representative of the last matched string found in the dictionary and appended thereto an extension character code portion representative of the next character taken from the input data stream. The dictionary is constructed large enough to provide a unique memory location for every possible pointer address. The unique pointer address, representative of a string of data in the input data stream, is employed as an address pointer to access the memory.