Method and apparatus for detecting valid data using selective modification of cyclic redundancy codes

摘要

A memory device and method, such as a flash memory device and method, includes a memory having a plurality of nonvolatile memory cells for storing stored values of user data. The memory device and method includes a memory controller for controlling the memory. The memory controller includes an encoder for encoding user write data for storage of code values as the stored values in the memory. The encoder includes an inserter for insertion of an indicator as part of the stored values for use in determining when the stored values are or are not in an erased state. The memory controller includes a decoder for reading the stored values from the memory to form user read data values when the stored values are not in the erased state.

主权项

1. A memory device comprising:
a memory; and a memory controller comprising an encoder, wherein the encoder is configured to receive first data to be written to the memory,
generate a first set of cyclic redundancy codes corresponding to the first data,determine whether the first data is valid data,in response to determining that the first data is valid data,
(i) modify the first set of cyclic redundancy codes to generate a second set of cyclic redundancy codes, and(ii) append the second set of cyclic redundancy codes to the first data to generate modified data, andin response to determining that the first data represents erased data, append the first set of cyclic redundancy codes to the first data to generate the modified data, wherein the memory controller is configured to write, to the memory, the modified data.