An error correcting code (ECC) function and a parity interface scheme providing a translation capability between the ECC and parity protocols is implemented for memory systems in personal computers (PCs). The ECC function addresses the problems of interfacing memory with a variety of other components that may communicate in words composed of differing numbers of bytes. A partial write function within an ECC module permits a read/modify/write operation without extra components, at faster speeds and with minimal use of the system bus. An improved parity/ECC protocol interface is implemented by choosing an appropriate ECC code to facilitate parity generation and checking. This is done by selecting a code that contains groupings of data bits corresponding to the desired parity scheme. The ECC XOR trees are modified to allow parity checking and error correction decode simultaneously, thereby eliminating the need for two sets of XOR trees in the interface.

ECC function with self-contained high performance partial write or read/modify/write and parity look-ahead interface scheme

In a read only semiconductor memory, signal lines such as data lines are subjected to an undesired parasitic capacitance which restricts the signal changing rate along the lines. The parasitic capacitance which is driven by a memory cell will become increasingly higher as the memory capacity is increased. According to the present invention, a differential sense amplifier is used to amplify the data signals which are read out of the memory cell. At the same time, a dummy cell is used to generate a reference potential which is to be referred to by the differential sense amplifier. In particular, a dummy cell arrangement is provided wherein each dummy cell includes at least two series-connected semiconductor elements to provide a predetermined dummy cell conductance to establish a reference value. Another aspect of the invention lies in the use of column switches between a common data line and data lines of the memory arrays for coupling only one data line at a time through the column switch to the sense amplifier. In addition, a built-in error-correcting-code circuit is provided which operates in conjunction with a selecting circuit so that memory cells delivering a predetermined set of data are spaced apart from one another by at least predetermined distances to reduce the likelihood of errors from immediately adjacent memory cells.

Semiconductor memory with an improved dummy cell arrangement and with a built-in error correcting code circuit

Advantage is taken of the presence of ordinary parity check bits occurring in the data flow in a computer or other information-handling system to improve error correction capability while at the same time providing simpler decoding. More particularly, the encoding and decoding system, methods, and devices herein include the capability of separating error correction in data bits and in parity check bits. In this regard, it is noted that the present invention therefore provides an improved memory system in which the parity check bits do not have to be stripped off prior to storage of data into a memory system with error correction coding redundancy built in. Instead of these parity check bits being stripped off, they are incorporated into a generalized and generalizable error correction system which produces a significantly simple decoding and error correction structure. The system provides for SEC-DED code capabilities while at the same time providing capabilities for correcting multiple odd numbers of errors occurring in distinct groups. Accordingly, the present invention provides encoding and decoding systems and methods, and a correspondingly improved memory system.

Error correction coding of data blocks with included parity bits

An error correction code, especially suited for memory chips with multi-bit outputs, in which parity bits are calculated for each byte of the word and check bits are calculated for the word as a whole. In a 4-byte, 32-bit word, eight bits of error correction can correct up to four errors if the errors are restricted to corresponding bits in the 4 bytes.

Error correction for multiple bit output chips

A plurality of processing units, each having a local memory connected thereto is disclosed. A write sense controller is also connected to each of the processing units to transmit a memory write word into a shared portion of local memory over a reflective memory line. Other write sense controllers receive the memory words from the reflective memory bus and cause them to be written into corresponding storage locations in the shared partitions of their local memories.

Method and apparatus for sharing information between a plurality of processing units

Apparatus for and method of providing single bit error correction and double bit error detection using through checking parity bits. A coding scheme is implemented which uses through checking parity bits appended to each byte as check bits. The remaining check bits are generated such that the combination of through checking parity bits and remaining check bits together provide single bit error correction and double bit error detection.

Gary David White

Papers

ECC Check bit generation using through checking parity bits

Erzeugung von fehlerkorrekturpruefbits unter benutzung von paritaetsbits zur durchlaufkontrolle