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.