Method for error detection/correction of multilevel cell memory and multilevel cell memory having error detection/correction function
First Claim
1. A method for error detection/correction of a multilevel cell memory having memory cells each for retaining two bits of data, the method comprising the steps of:
- assigning binary bit addresses, for error detection, said binary bit addresses designating individual bits of said memory cells such that each pair of said binary bit addresses corresponding to each of said memory cells is mutually exclusive in each digit;
generating, for each digit of said binary bit addresses, first parity codes including a parity code of write data corresponding to all of said binary bit addresses having “
0”
in said digit and a parity code of said write data corresponding to all of said binary bit addresses having “
1”
in said digit;
generating first parity codes of read data corresponding to said binary bit addresses whose combinations are the same as used in the generation of said first parity codes of said write data, when reading data from said memory cells; and
detecting a presence of one memory cell storing erroneous data in both bits when said first parity codes generated in the read operation are all different from said first parity codes generated in the write operation.
10 Assignments
0 Petitions
Accused Products
Abstract
Binary bit addresses for error detection designating the individual bits of multilevel memory cells for retaining two bits of data, respectively, are assigned so that pairs of the binary bit addresses corresponding to each of the memory cells are mutually exclusive in each digit. For each digit of the binary bit addresses, first parity codes including a parity code of data corresponding to all the binary bit addresses having “0” in the digit and a parity code of data corresponding to all the binary bit addresses having “1” in the digit are generated for both write data and read data. The presence of a memory cell storing erroneous data in both bits is detected when all the first parity codes of the read data are different from the first parity codes of the write data. Thus, the multilevel cell memory can perform reliable error detection/correction by a simple method.
34 Citations
17 Claims
-
1. A method for error detection/correction of a multilevel cell memory having memory cells each for retaining two bits of data, the method comprising the steps of:
-
assigning binary bit addresses, for error detection, said binary bit addresses designating individual bits of said memory cells such that each pair of said binary bit addresses corresponding to each of said memory cells is mutually exclusive in each digit; generating, for each digit of said binary bit addresses, first parity codes including a parity code of write data corresponding to all of said binary bit addresses having “
0”
in said digit and a parity code of said write data corresponding to all of said binary bit addresses having “
1”
in said digit;generating first parity codes of read data corresponding to said binary bit addresses whose combinations are the same as used in the generation of said first parity codes of said write data, when reading data from said memory cells; and detecting a presence of one memory cell storing erroneous data in both bits when said first parity codes generated in the read operation are all different from said first parity codes generated in the write operation. - View Dependent Claims (2, 3)
-
-
4. A multilevel cell memory having an error detection/correction function, comprising:
-
a plurality of memory cells each for retaining two bits of data; a first generating circuit for assigning binary bit addresses, for error detection, designating individual bits of said memory cells, such that each pair of said binary bit addresses corresponding to each of said memory cells is mutually exclusive in each digit, generating, for each digit of said binary bit addresses, first parity codes including a parity code of write data corresponding to all of said binary bit addresses having “
0”
in said digit and a parity code of said write data corresponding to all of said binary bit addresses having “
1”
in said digit, andgenerating first parity codes of read data corresponding to said binary bit addresses whose combinations are the same as used in the generation of said first parity codes of said write data, when reading data from said memory cells; and a first detecting circuit for detecting a presence of one memory cell storing erroneous data in both bits when said first parity codes generated in the read operation are all different from said first parity codes generated in the write operation. - View Dependent Claims (5, 6, 7, 8)
-
-
9. A method for error detection/correction of a multilevel cell memory having memory cells each for retaining a plurality of bits of data, the method comprising the steps of:
-
constituting a plurality of first groups by selecting two bits from each of said memory cells as a bit pair; and
,for each of said first groups, assigning two binary first addresses designating each bit of the bit pair for each of said memory cells such that said two binary first addresses are mutually exclusive in each digit, generating, for each digit of said binary first addresses, first parity codes including a parity code of write data corresponding to all of said binary first addresses having “
0”
in said digit and a parity code of said write data corresponding to all of said binary first addresses having “
1”
in said digit,generating first parity codes of read data corresponding to said binary first addresses whose combinations are the same as used in the generation of said first parity codes of said write data, when reading data from said memory cells, and detecting a presence of one memory cell storing erroneous data in both bits of a bit pair thereof in an area allocated to each of said first groups when said first parity codes generated in the read operation are all different from said first parity codes generated in the write operation. - View Dependent Claims (10, 11, 12)
-
-
13. A multilevel cell memory having an error detection/correction function, comprising:
-
a plurality of memory cells each for retaining a plurality of bits of data; a plurality of first groups each being constituted by selecting one of two bits from each of said memory cells; a first generating circuit for assigning two binary first addresses respectively designating one bit of each bit pair of said memory cells for each of said first groups such that said two binary first addresses are mutually exclusive in each digit, generating, for each digit of said binary first addresses, first parity codes including a parity code of write data corresponding to all of said binary first addresses having “
0”
in said digit and a parity code of said write data corresponding to all of said binary first addresses having “
1”
in said digit, for each of said first groups, andgenerating, for each of said first groups, first parity codes of read data corresponding to said binary first addresses whose combinations are the same as used in the generation of said first parity codes of said write data, when reading data from said memory cells; and a first detecting circuit for detecting, for each of said first groups, a presence of one memory cell storing erroneous data in both bits of a bit pair thereof in an area allocated to each of said first groups when said first parity codes generated in the read operation are all different from said first parity codes generated in the write operation. - View Dependent Claims (14, 15, 16, 17)
-
Specification