Computer Memory Error Correction
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computer data storage that can detect and correct the most common kinds of internal data corruption. ECC memory is used in most computers where data
Corrected Memory Error Threshold Exceeded
corruption cannot be tolerated under any circumstances, such as for scientific or error correction in computer networks financial computing. Typically, ECC memory maintains a memory system immune to single-bit errors: the data that is read from error correction in computer architecture each word is always the same as the data that had been written to it, even if one or more bits actually stored have been flipped to the wrong state.
Error Correction And Detection In Computer Network
Most non-ECC memory cannot detect errors although some non-ECC memory with parity support allows detection but not correction. Contents 1 Problem background 2 Solutions 3 Implementations 4 Cache 5 Registered memory 6 Advantages and disadvantages 7 References 8 External links Problem background[edit] Electrical or magnetic interference inside a computer system can cause a single bit of dynamic random-access memory (DRAM) to spontaneously
Error Correcting Ram
flip to the opposite state. It was initially thought that this was mainly due to alpha particles emitted by contaminants in chip packaging material, but research has shown that the majority of one-off soft errors in DRAM chips occur as a result of background radiation, chiefly neutrons from cosmic ray secondaries, which may change the contents of one or more memory cells or interfere with the circuitry used to read or write to them.[2] Hence, the error rates increase rapidly with rising altitude; for example, compared to the sea level, the rate of neutron flux is 3.5 times higher at 1.5km and 300 times higher at 10–12km (the cruising altitude of commercial airplanes).[3] As a result, systems operating at high altitudes require special provision for reliability. As an example, the spacecraft Cassini–Huygens, launched in 1997, contains two identical flight recorders, each with 2.5gigabits of memory in the form of arrays of commercial DRAM chips. Thanks to built-in EDAC functionality, spacecraft's engineering telemetry reports the number of (correctable) single-bit-per-word errors and (uncorrectable) double-bit-per-word errors. During the first 2.5years of flight, the spacecraft reported a near
citations to reliable sources. Unsourced material may be challenged and removed. (August 2008) (Learn how and when to remove this template message) In information theory and coding theory with ecc memory vs non ecc applications in computer science and telecommunication, error detection and correction or error
Error Correction Code
control are techniques that enable reliable delivery of digital data over unreliable communication channels. Many communication channels are subject ecc encryption to channel noise, and thus errors may be introduced during transmission from the source to a receiver. Error detection techniques allow detecting such errors, while error correction enables reconstruction of https://en.wikipedia.org/wiki/ECC_memory the original data in many cases. Contents 1 Definitions 2 History 3 Introduction 4 Implementation 5 Error detection schemes 5.1 Repetition codes 5.2 Parity bits 5.3 Checksums 5.4 Cyclic redundancy checks (CRCs) 5.5 Cryptographic hash functions 5.6 Error-correcting codes 6 Error correction 6.1 Automatic repeat request (ARQ) 6.2 Error-correcting code 6.3 Hybrid schemes 7 Applications 7.1 Internet 7.2 Deep-space telecommunications 7.3 Satellite https://en.wikipedia.org/wiki/Error_detection_and_correction broadcasting (DVB) 7.4 Data storage 7.5 Error-correcting memory 8 See also 9 References 10 Further reading 11 External links Definitions[edit] The general definitions of the terms are as follows: Error detection is the detection of errors caused by noise or other impairments during transmission from the transmitter to the receiver. Error correction is the detection of errors and reconstruction of the original, error-free data. History[edit] The modern development of error-correcting codes in 1947 is due to Richard W. Hamming.[1] A description of Hamming's code appeared in Claude Shannon's A Mathematical Theory of Communication[2] and was quickly generalized by Marcel J. E. Golay.[3] Introduction[edit] The general idea for achieving error detection and correction is to add some redundancy (i.e., some extra data) to a message, which receivers can use to check consistency of the delivered message, and to recover data determined to be corrupted. Error-detection and correction schemes can be either systematic or non-systematic: In a systematic scheme, the transmitter sends the original data, and attaches a fixed number of check bits (or parity data), which are derived from the data bits by some det
> detection/correction circuitry that does a more thorough job of detecting > memory errors? The memory is just memory. In general, memory doesn't do parity or ECC, that http://www.brouhaha.com/~eric/computers/ecc.html is done by memory control logic on the motherboard, in the chip set, or http://searchnetworking.techtarget.com/definition/ECC (as in the 21066) in the CPU. The memory only has to store the parity or ECC bits, just as it stores the data bits. Parity is implemented on most PCs with one parity bit per byte. For a 32-bit word size there are four parity bits, for a total of 36 bits that have error correction to be stored in the memory. On most Pentium and Pentium Pro systems, and a few 486 systems, there is a 64-bit wide memory data path, so there are eight parity bits, for a total of 72 bits. When a word is written into memory, each parity bit is generated from the data bits of the byte it is associated with. This is done by a tree of exclusive-or error correction in gates. When the word is read back from the memory, the same parity computation is done on the data bits read from the memory, and the result is compared to the parity bits that were read. Any computed parity bit that doesn't match the stored parity bit indicates that there was at least one error in that byte (or in the parity bit itself). However, parity can only detect an odd number of errors. If an even number of errors occur, the computed parity will match the read parity, so the error will go undetected. Since memory errors are rare if the system is operating correctly, the vast majority of errors will be single-bit errors, and will be detected. Unfortunately, while parity allows for the detection of single bit errors, it does not provide a means of determining which bit is in error, which would be necessary to correct the error. This is why parity is only an Error Detection Code (EDC). ECC is an extension of the parity concept. ECC is usually performed only on complete words, rather than individual bytes. In a typical ECC system with a 64-bit data word, there would be 7 ECC bits. Each ECC bit is calculated as t
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