Method for choosing replacement lines in a two dimensionally redundant array

Claim 1

A method for assigning redundant lines in a two dimensional array having at least one redundant line in a first direction and at least one redundant line in a second direction perpendicular to said first direction and having a first plurality of original lines in said first direction and a second plurality of original lines in said second direction, the intersections of said original lines in said first and second directions defining elements, comprising the steps of: (a) determing which of said elements are failures; (b) scanning along a selected original line sequentially selected from said original lines in said first direction to determine the number of failures in said selected line; (c) determining if the number of failures in said selected line exceeds the total number of remaining redundant lines in said second direction; if the number of said failures in any said first selected line exceeds the total number of remaining redundant lines in said second direction, then (d) replacing each said exceeding selected line with a redundant line in said first direction, wherein said replacing corrects all of said failures in said replaced line, (e) decrementing the total numberof remaining redundant lines in said first direction, and (f) repeating steps (b) through (e) with an interchange of said first and second directions before step (b); and if steps (b) through (f) do not correct all said failures, then executing following steps (g) through (j): (g) masking all remaining failures in a selected set of a selected number of original lines in a selected one of said two directions and decrementing the number of remaining redundant lines in said selected direction by said selected number, said selected number being initially set to one; (h) determining if all failures not masked in step (g) can be corrected by the remaining redundant lines in said first and second directions by a method comprising the step of comparing the number of failures in an original line in a direction other than said selected direction with the number of remaining redundant lines in said selected direction; (i) if in step (h), it has been determined that all said non-masked failures cannot be corrected, then repeating steps (g) and (h) for another selected set of said selected number of said original lines in said selected direction; and (j) if in steps (g) through (i), it has been determined that all said non-masked failures cannot be fixed, then repeating steps (g) through (i) for said selected number being increased by one until said selected number is greater than the number of remaining original lines in said selected direction containing failures.

Claim 2

A method for assigning redundant lines in a two dimensional array having at least one redundant line in a first direction and at least one redundant line in a second direction perpendicular to said first direction and having a first plurality of original lines in said first direction and a second plurality of original lines in said second direction, the intersections of said original lines in said first and second directions defining elements, comprising the steps of: (a) determing which of said elements are failures; (b) scanning along a selected original line sequentially selected from said original lines in said first direction to determine the number of failures in said selected line; (c) determining if the number of failures in said selected line exceeds the total number of remaining redundant lines in said second direction; if the number of said failures in any said first selected line exceeds the total number of remaining redundant lines in said second direction, then (d) replacing each said exceeding selected line with a redundant line in said first direction, wherein said replacing corrects all of said failures in said replaced line, (e) decrementing the total numberof remaining redundant lines in said first direction, and (f) repeating steps (b) through (e) with an interchange of said first and second directions before step (b); and if steps (b) through (f) do not correct all said failures, then executing following steps (g) through (j): (g) masking all remaining failures in a selected set of a selected number of original lines in a selected one of said two directions and decrementing the number of remaining redundant lines in said selected direction by said selected number, said selected number being initially set to one; (h) determining if all failures not masked in step (g) can be corrected by the remaining redundant lines in said first and second directions by a method comprising the step of comparing the number of failures in an original line in a direction other than said selected direction with the number of remaining redundant lines in said selected direction; (i) if in step (h), it has been determined that all said non-masked failures cannot be corrected, then repeating steps (g) and (h) for another selected set of said selected number of said original lines in said selected direction; and (j) if in steps (g) through (i), it has been determined that all said non-masked failures cannot be fixed, then repeating steps (g) through (i) for said selected number being increased by one until said selected number is greater than the number of remaining original lines in said selected direction containing failures.