A 4 Byte 18 Ns ECC for Hard and Soft Correction

The constant increase of memory size and the search for improving the reliability in the recent computers have led to introduce a certain amount of hardware redundancy in an attempt to improve the Mean Time Between Failure. The memory part has received a special attention because of the amount of hardware involved making the memory a large contributor to the total failure rate of the machine. The situation is worse with the use of the high density Random Access Memory modules subject to the so-called "soft error". A phenomenon due, among other things, to the residual radio activity of the materials used to build the module itself energy of which is sometimes sufficient to alter the contents of the very low capacitor, typically 50 to 70 femtoFarad, that serves as memory element.