A study of two approaches for reconfiguring fault-tolerant systolic arrays

Presents a critical study of two approaches, the classical RC-cut approach and H.T. Kung and M.S. Lam´s (Proc. 1984 MIT Conf. Advanced Res. VLSI p.74-83, 1984) RCS-cut approach, for reconfiguring faulty systolic arrays. The amount of cell (processing element) redundancy needed to ensure successful reconfiguration into an n×n array is considered. It is shown that no polynomial bounded redundancy is sufficient for the classical approach, whereas O(n²log n) redundancy is sufficient for the Kung and Lams approach. The number of faulty cells that can be tolerated in a given array regardless of their locations is characterized and derived. It is shown that, for both approaches, in almost all cases a square array has better fault tolerance than a rectangular array having the same number of cells. A minimal fault pattern in a 2n×2n array with 3n+1 faults that is not reconfigurable into an n×n array using either of the two approaches is established