Application of Error-Correcting Codes in Computer Reliability Studies

The use of error-correcting codes as one of the important techniques to increase computer system reliability is introduced. The different codes used in the central processing unit (CPU) are described. Since the CPU usually contains the data path, logic, and arithmetic units, the codes used in this area are error-detecting codes, such as parity check codes and residue codes. The codes used or suggested for the memory system are discussed, emphasis being placed on parity check codes, two-dimensional codes, Hamming codes and other recently developed codes. The various codes used in the input/output system are presented. The input/output area of the computer system is relatively unreliable as compared with CPU or memory; therefore, error-correcting codes used in this area usually are much more powerful than single parity check codes. These include codes for the magnetic tape, disk, and drum units. The error coding techniques are compared with other techniques for increasing computer system reliability. The future trend of using error-correcting codes in a computer system is also discussed.