What is ECC?
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Error-correction code (ECC) is redundant data that a sender adds to its messages in a system of error control for data transmission called forward error correction (FEC). This allows the receiver to detect and correct errors (with some limitations) without asking the sender for additional data. The advantages of FEC are that a back-channel is not required and retransmission of data can often be avoided though this is achieved at the cost of higher bandwidth requirements. FEC is therefore applied where retransmissions are relatively costly or impossible. In particular, FEC information is usually added to most mass storage devices to protect against damage to the stored data. For instance, electrical or magnetic interference inside a computer system can cause a single bit of DRAM to flip to the opposite state. This problem can be mitigated by using DRAM modules that include extra (redundant) memory bits and memory controllers that exploit these bits. These extra bits are used to record parity or to use an ECC. Parity allows the detection of an odd number of wrong bits. The ECC may allow a single-bit error to be corrected and double-bit errors to be detected. Error detection and correction in computer systems keeps going in and out of vogue. Seymour Cray famously said "parity is for farmers" to explain why he left it out of the CDC 6600. He included parity in the CDC 7600, and reputedly said "I learned that a lot of farmers buy computers." |
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| 2002-05-08 | Speed sensors This application note describes two types of speed sensor offered by TAG Electronic Systems for automotive applications: inductive and differential Hall effect. |
| 2004-04-01 | Design considerations when upgrading to a 32bit MCU When contemplating a move from a 16bit MCU to a 32bit device, multiple design issues should be considered. |
| 2005-08-16 | How to use on-target rapid prototyping This article discusses on-target rapid prototyping and how it differs from conventional approaches |
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