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Extended Error Correction with an Error Correction Code

IP.com Disclosure Number: IPCOM000052024D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 32K

Publishing Venue

IBM

Related People

Chen, CL: AUTHOR [+2]

Abstract

This scheme may be used to extend the error correction capability of an error correction code (ECC).

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Extended Error Correction with an Error Correction Code

This scheme may be used to extend the error correction capability of an error correction code (ECC).

The parity matrix shown in Fig. 1 is for an ECC which automatically corrects double bit errors and detects triple bit errors in a block of 144-bit code word that consists of 128 data bits and 16 check bits. Since the number of 1's in each row of the matrix is even, the bit-by-bit complement of a code word is also a code word. This property, referred to as a C-invariant property, is essential for the application of the present invention.

The invention is to extend the correction capability of the ECC to the correction of 3-bit errors. The 3-bit errors may consist of 1 stuck hard error and 2 other mixed hard/soft errors. The major application of the extended error correction is to the correction of soft errors, while stuck hard errors (up to two) are allowed to accumulate in the paging store BSM (basic storage module).

Fig. 2 is a block diagram of the extended error correction scheme. The BUFFER 10 is used for the storage of 256 ECC words (1 page of data). The XOR 12 represents 18 3-way in and 1 out exclusive OR gates. The ECC LOGIC 14 generates an uncorrectable error (UE) signal and, in the case of correctable errors, generates error locations. Normally, when the UE signal is off, the CONTROL input to XOR 12 is set at 0. In this case XOR 12 is an error corrector that inverts the input data bits at positions specified by the error location lines. A code word is corrected in 8 installments of 18 bits.

When there is a UE within a page, the channel is notified for the page bein...