Fast and Efficient Totally Self-Checking Checkers for m-out-of-(2m ± 1) Codes

This note is concerned with the design of fast totally self-checking checkers for m-out-of-(2m ± 1) codes. The new method uses only three levels of gates, and is based on the partitioning of the input lines into m blocks of two lines per block except for the last block. A first level of two-input AND and OR gates realizes the majority functions T(ki ≥ 1) and T(ki ≥ 2). These are combined through AND gates of a second level into the so-called product functions Pj1j2...jm, one for each class of input codewords that have jl, j2,···, jm 1's in the corresponding blocks of the input lines. Finally, two OR gates (third level) partition the product functions into two. The property of totally self-checking operation is achieved through the proper partitioning of the product functions into two classes. This note presents a systematic method of such partitioning. Also, the note determines the cost of these checkers and compares them to previous designs.